The kinetics of maternal and self-developed Streptococcus suis-specific antibodies

The kinetics of maternal and self-developed Streptococcus suis-specific antibodies | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The kinetics of maternal and self-developed Streptococcus suis-specific antibodies Sandra Vreman, Rutger Jansen, Mikael Bastian, Patricia Beckers, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4768277/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 07 Feb, 2025 Read the published version in Porcine Health Management → Version 1 posted 9 You are reading this latest preprint version Abstract Background: Streptococcus suis (S. suis) infections are responsible for a large disease burden in piglets after weaning, compromising animal welfare and increasing antibiotic use. The immune gap caused by decreased maternal-derived antibodies (MDA) and insufficient acquired antibodies in weaned pigs could be a key factor for increased susceptibility to S. suis infections. To better understand this, two studies were performed. Study I evaluated the associations between sow antibodies in colostrum and serum, birth parameters (e.g., birth weight, colostrum intake and piglet growth) and the levels of S. suis -specific (serotypes 2 and 9) antibodies in one-day-old piglets from four farms. Subsequently, Study II used one of these farms to evaluate S. suis -specific and total antibody kinetics in piglets (10 litters with 6 selected piglets per litter, total n=60) from birth until10 weeks of age. Additionally, tonsil swabs from sows and piglets were taken to evaluate the S. suis tonsillar carrier status (serotypes 2 and 9) before and after weaning. Results: High variability in serum and colostrum antibody levels was observed between and within the four farms (study I). In Study II, there was a decrease in S. suis- specific MDA after 24 hours of age, with the lowest level occurring at approximately 18/19 days of age. Afterwards, there was an increase in specific antibodies, most likely due to acquired immunity. Colostrum intake, birth weight and 24-h weight gain after birth were important parameters that were positively associated with S. suis antibody levels in piglets after birth but also affected these antibody levels at a later age. All the piglet tonsils were colonized with S. suis serotype 9 before weaning, while the prevalence of serotype 2 increased after weaning. Conclusions: The lowest level of S. suis -specific antibodies was detected just before weaning, which contributes to piglet susceptibility to S. suis infections. Farmers and veterinarians should focus on piglets with low birth weights, late-born piglets, and/or piglets with low colostrum intake because these parameters reduce both the S. suis -specific MDA preweaning and the specific antibodies acquired postweaning. Streptococcus suis piglet sow antibodies colostrum immune gap maternal-derived antibodies (MDA) field study Figures Figure 1 Figure 2 Figure 3 Figure 4 Background Streptococcus suis (S. suis) is an important pathogen in pigs, resulting in infections that lead to decreased performance and increased mortality ( 1 , 2 ), with significant consequences for swine health, welfare, and porcine production worldwide. S. suis infections usually occur in piglets up to 10 weeks of age, especially around weaning, causing meningitis, arthritis, endocarditis, polyserositis with associated lameness, neurologic signs and/or sudden death ( 1 , 3 ). S. suis is a very diverse pathogen. Currently, 29 serotypes of S. suis are recognized based on their capsular polysaccharides (CPSs) surrounding the bacterium ( 4 ). Although S. suis serotype 2 is most frequently isolated from clinical cases worldwide, the number of serotype 9 isolates from diseased pigs has increased substantially in Europe ( 5 , 6 ). Both adult and young pigs can carry S. suis in the nose, tonsils, and nasopharynx as well as in the genital and gastrointestinal tract ( 7 , 8 ), and pigs are often colonized by more than one serotype ( 9 , 10 ). These carrier pigs are often the source of infection for young sensitive piglets ( 11 ), but sows may also infect their own litters with saliva ( 12 ), and transmission during birth or suckling has been reported ( 13 ). A major cause of the high incidence of S. suis infections postweaning is the immune gap induced by the decrease in maternal-derived antibodies (MDA) after birth and the slow development of acquired antibodies in piglets ( 14 , 15 ). Piglets are born without systemic circulating antibodies, and MDA are only transferred through the uptake of IgG via the intestine from colostrum within the first 24 h after birth ( 16 ). These passively acquired antibodies enter the bloodstream of piglets and act as a protective shield throughout the body in the same way as actively produced antibodies ( 17 ). Studies have shown that clinical signs of S. suis infection appear when the level of MDA is low (between 4–8 weeks of age) ( 18 , 19 ) and that the production of S. suis antibodies slowly increases at the end of the postweaning period, which increases the resistance of pigs to S. suis infection at a later age ( 20 ). In addition, regardless of the antibody level from vaccinated sows or carriers, S. suis MDA were cleared before weaning ( 21 , 22 ). More research on the role of S. suis- specific antibodies in sow serum and colostrum and piglet birth parameters, such as colostrum intake and S. suis -specific antibody levels, can contribute to a better understanding of the lasting clearance of MDA in piglets from birth toward the development of acquired antibodies against S. suis . In Study I, we evaluated the associations of sow and piglet parameters around birth with total (IgA, IgM, and IgG) and S. suis -specific (serotypes 2 and 9) antibody levels (IgG + IgM) in one-day-old piglets on four farms in the Netherlands. Subsequently, in Study II, we used one of these farms to evaluate the kinetics of S. suis serotypes 2 and 9 and total IgA, IgM, and IgG antibodies in piglets from birth to 10 weeks of age. Additionally, from sows and piglets before and after weaning, tonsil swabs were taken to evaluate the S. suis status (serotypes 2 and 9) and the development of tonsil colonization in piglets. Methods Experimental design Study I was a cross-sectional study with samples for diagnostic purposes performed on four farrow-to-finish farms (A to D) in the Netherlands with a high incidence of S. suis in weaned piglets. The study was performed from 2018–2019. Within the two years preceding the sampling, the piglets on these farms suffered from clinical disease related to S. suis serotype 2 and 9 infections. Growth-promoting antibiotics were not used by any of the four farms. On farm D, the sows were vaccinated with an oil-adjuvanted autogenous vaccine (Ceva Biovac) consisting of S. suis serotype 2 (2 x 2017 brain isolate) and 9 (2017 brain isolate), Pasteurella multocida (1 x 2015 lung isolate) and Actinobacillus pleuropneumoniae (2 x 2016 lung isolate). The animals treated with the autogenous vaccine received a primary vaccination (2.0 ml IM) at 60 days of gestation, which was boosted (2.0 ml IM) at 90 days of gestation. Subsequent boostering was performed at 90 days of each following gestation. Sows on all four farms were fed a commercial pelleted diet and housed in individual farrowing crates compliant with national legislation for the housing of farrowing sows. Farms were visited for S. suis problem-related consulting. From each farm, four to six sows that started their farrowing process during the routine consultancy were included in the study. On farms A, B and C, the selection of the desired number of farrowing sows was completed on one day; for farm D, this selection was completed in two days. The sows were observed during farrowing, and no additional help or care was given during birth of the piglets. Within 5 min after birth, the piglets were weighed. The time of birth and body weight at birth (BWb) were recorded. For identification of the piglets, numbered ear tags were used. For study I on farms A-D, a total of 20 sows and 23 piglets were included (Supplementary Table 1). Immediately after the birth of the first piglet (< 10 minutes), a colostrum sample was collected from the first three cranial teats of the upper half of the udder of the sow. The sampled teats were cleaned with tissue to remove dust and debris. Teats were milked manually until a volume of 10 ml of colostrum was obtained. The colostrum was refrigerated immediately after collection, aliquoted and stored at -20°C until analysis by ELISA. One day after birth, the piglets were weighed again to determine the 24-hour body weight gain after birth (average daily gain D1 (ADG D1)), and the time of weighing was recorded. The colostrum intake of the piglets was calculated based on the parameters BWb, WG and the duration of colostrum intake (D) using the following equation: -106 + 2.26 WG + 200 BWb + 0.111d-1414 WG/D + 0.0182 WG/BWb, as previously published ( 23 ). Blood samples were taken from the selected sows and piglets, and the serum was stored at -20°C until analysis by ELISA. One year after the finalization of Study I, Study II started on Farm B. Among the four farms in Study I, this farm was the best equipped to perform a field study with a longer duration and had enough sows for a high likelihood of 10 spontaneous farrows during one day (1165 head sow herds with 55 farrows per weekly batch). In this study, which lasted from March 2020 to May 2020, piglets were born by the natural onset of farrowing. The farm was visited during the day of most natural farrowing (day 115 of gestation, study day 0). Ten sows that were farrowing during that day were included in the study. A total of 149 piglets were delivered to these ten sows. As described previously, all the piglets were weighed directly after birth (BWb), birth order was documented, and a standard ear tag was used for identification. Directly after birth, the umbilical cord was squeezed to obtain a precolostral-fed blood sample of at least 0.5 ml, which was successful for 104 out of the 149 piglets (69.7%). Colostrum samples were collected and processed as described earlier, and the colostrum intake of each pig was calculated. On day 1, piglets with birth weights above 1,100 grams were selected to reduce the risk of preweaning mortality ( 24 , 25 ), from which a successful umbilical cord blood sample (> 0.5 ml whole blood) could be obtained. From these piglets, six piglets per sow were selected for the study, which were equally divided among littermates from the first to the last born piglet. There was no selection for sex. During the suckling period, the piglets were weighed, and blood samples were taken at 1, 6, 13, 20, and 23 days of age and during the postweaning period at 27, 35, 42, 56, and 69 days of age. Pigs were weaned at the age of 23 days, and at weaning, the siblings were kept together in a pen. On day 1, blood samples were also taken from the ten selected sows. The serum of these sows and the serum of the piglets were stored at -20°C until analysis by ELISA. During the study period (from birth until day 69), eight of the 60 piglets (13%) died between day 4 and day 50, which is in line with the average mortality rate (measured from birth until 69 days) on this farm and other farms ( 26 – 28 ). Due to the fully closed nature of the pens, there was no direct contact between piglets from different litters before and after weaning, limiting the potential for S. suis to be carried over by direct pig-to-pig contact. Tonsillar samples from the piglets were collected at 23, 34 and 69 days of age and from the sows at weaning. Surgical pliers were used to open the mouths of the pigs. The sows’ mouths were opened using a metal mouth gag. Tonsillar samples were obtained by rubbing an eSwab™ 480CE (Copan Diagnostics, Inc., Carlsbad, CA, USA) on the tonsillar surface for several seconds. The swabs were immediately placed in eSwab™ 480CE tubes containing liquid Amies transport medium and transported to the laboratory at ambient temperature, after which the DNA was isolated for qPCR as described below. Quantification of porcine IgA, IgM and IgG Greiner MICROLON®600 high binding ELISA plates were coated overnight at RT with antibodies against porcine IgA, IgM and IgG diluted in carbonate-bicarbonate buffer (Sigma Aldrich C3041, Saint Louis, MO, USA); see Supplementary Table 2 for details about the antibodies and dilutions. Blocking was performed with PBS + 1% BSA at pH 7.2 for 1 h at RT. Dilutions of sow and piglet sera, colostrum and umbilical cord blood samples were prepared in PBS and added to the wells. Bound antibodies were detected with the conjugates and dilutions described in using tetramethylbenzidine (TMB) as a substrate (Supplementary Table 2). Reactions were stopped after 10–15 min by the addition of 0.5 M H 2 SO 4, and extinctions (at 450 nm) were measured on a microplate reader. Primary and secondary antibody incubations were performed for 1 h at RT, and the wells were washed three times with PBS after both incubations. To quantify the amount of IgA, IgM and IgG, a reference pig serum (Bethyl RS10-107, Bethyl Laboratories Inc., Montgomery, Texas, USA) was diluted in PBS to stock solutions of 3.6 µg IgA/ml, 3.5 µg IgM/ml and 3.5 µg IgG/ml. Serial dilutions of the stock solution of the reference serum were measured in duplicate, and a standard curve was fitted using 4-parameter logistics with SoftMax Pro Software. The standard curve was used to interpolate the OD450 values of individual samples to concentrations relative to the standard curve (µg/ml). All sera and other matrices from the A-D farms were analyzed in duplicate, and the mean was used in the calculations. For Study II, the sera and colostrum were analyzed as single samples. The optimal dilutions of the coating antibodies, the matrices, the conjugates and the positive internal control sera were determined during preliminary standardizations. Porcine antibodies against whole cells of S. suis serotypes 2 and 9 S. suis serotype 2 strain 10 and serotype 9 strain 8067 were grown overnight in Todd Hewitt broth (THB) at 37°C without shaking. The next day, the bacterial cells were harvested, washed with PBS, and inactivated by treatment with 0.5% formaldehyde for 1 h at room temperature (RT) with intermittent gentle mixing. Inactivated cells were washed and resuspended in PBS. Greiner MICROLON®600 high binding ELISA plates were coated overnight at RT with approximately 1E6 CFU/well of inactivated S. suis serotype 2 or S. suis serotype 9 bacteria in PBS. Blocking was performed with PBS + 1% BSA at pH 7.2 for 1 h at RT. A series of dilutions of sow and piglet serum, colostrum and umbilical blood samples were prepared in PBS and added to the wells. Bound antibodies were detected with a 1:10,000 dilution of peroxidase (PO)-conjugated anti-porcine-IgL (WBVR, mouse antibody (MAb) clone 27.2.1; ( 29 )) using tetramethylbenzidine (TMB) as a substrate. Reactions were stopped after 10–15 min by the addition of 0.5 M H 2 SO 4, and extinctions (at 450 nm) were measured on a microplate reader. Serum and secondary antibody incubations were performed for 1 h at RT, and the wells were washed three times with PBS after both incubations. Serum samples from pigs that survived an experimental infection with S. suis serotype 2 strain 10 or S. suis serotype 9 strain 8067 were used as positive controls for the serotype 2 and serotype 9 ELISAs, respectively. Serial dilutions of the positive control were measured in duplicate, and a standard curve was fitted using 4-parameter logistics with SoftMax Pro Software. The standard curve was used to interpolate the OD450 values of individual samples to concentrations relative to those of the positive control (% positivity). All sera were analyzed in duplicate, and the mean was used in the calculations. The optimal dilutions of the coating antibodies, the matrices, the conjugates and the positive internal control sera were determined during preliminary standardizations. Colonization of tonsils by S. suis serotypes 2 and 9 DNA was isolated from tonsil swabs. For this purpose, the eSwab™ 480CE were thawed during 30 minutes, swabs were individually vortexed for 20 seconds and amies fluid was immediately used for isolation. Prior to DNA isolation, the samples were treated with an enzyme mixture to lyse the bacterial cells. Then, 46 µl of lysing mixture containing 20 µl of lysozyme (100 mg/ml), 1 µl of mutanolysin (5000 U/ml) and 25 µl of protein kinase K (600 AU/ml, included in the Qiagen DNeasy Blood & Tissue Kit) was added to 154 µl of the swab sample. The samples were mixed by vortexing and incubated for 30 min at 37°C. Then, 200 µl of AL buffer from the Qiagen Blood and Tissue Kit was added, and the samples were vortexed for 15 seconds and incubated for 30 min at 56°C. Then, 200 µl of 100% ethanol was added, and the samples were vortexed for 15 sec. Purification was continued from step 4 of the Qiagen DNeasy Blood & Tissue Kit manual. Purified DNA was eluted in 30 µl of SuperQ® water. The primers and probe sequences specific for the cpsJ locus of S. suis serotype 2 ( cps2J ) and the cpsH locus of S. suis serotype 9 ( cps9H) have been previously described ( 30 ). For each cps2J PCR or csp9 H PCR a standard curve control was added containing pUC57 plasmid with the specific fragment of the cps2J of cps9H gene. Standard curves controls of pUC57- cps2J and pUC57- cps9H consist of dilutions 1x10 − 3 -1x10 − 9 of a 10 0 stock with a concentration of approximately 3.5x10 8 copies/ul. Standard curves of internal positive controls (IPC) of pUC57- cps2J -IPC and pUC57- cps9H -IPC consist of dilutions 1x10 − 4 -1x10 − 8 of a 10 0 stock with concentration of approximately 3.5x10 8 copies/ul. The slope for the standard curves should lie between − 3.1 and − 3.5. Negative controls containing no DNA were also included. Each PCR sample had a final volume of 20 µl and contained: 10 µl of 2X Taqman Fast Universal PCR mix (Thermo Fisher Scientific), 1,8 µl of 10 pmol of forward primer (F-cps2J or F-cps9H), 1,8 µl of 10 pmol of reverse primer (R-cps2J or R-cps9H), 0,25 µl of test probe (FAM-cps 2J or FAM-cps9H), and 0.25 µl of IPC probe (VIC-IPC_cps2J/cps9H). To the experimental samples 2,5 µl of DNA isolated from tonsil swabs was added or 2,5µl of the standard curve dilution or water for the standard and negative controls. One microliter of IPC DNA (1x10 − 7 dilution of pUC57 -cps2J-IPC or pUC57- csp9H-IPC) was added to all samples except the IPC standard curve samples. The reactions were supplemented with SuperQ® water (Merck Millipore) up to a volume of 20 µl. PCR was performed on an ABI 7500 FAST real-time PCR system (Applied Biosystems). The PCR conditions were as follows: 5 min at 95°C, 40X [15 sec at 95°C, 1 min at 60°C], probe detection at FAM/VIC, and a QPCR cutoff of 0.1. The amplification curves were analyzed with the ABI 7500 2.3 software from Applied Biosystems. The uninhibited Ct for 1x10 − 7 ng of pUC57- cps2J DNA and pUC57- cps9H DNA was between 30 and 31 in both PCRs. Ct values below 35 were considered positive. Statistical analysis The ELISA data were log10 (x + 1) transformed to obtain normally distributed data. Comparisons were performed between the four farms using ordinary one-way ANOVA with Tukey’s multiple comparisons test (GraphPad Prism 9, USA). Significance across farms was tested with a one-sample t test on the Pearson coefficients to determine whether these were significantly different from 0 (R)( 31 ). Linear-mixed model: (R, lme4 package). For each antibody (Ss2Ab, Ss9Ab and IgG), a default “null hypothesis” model (referred to below as H0 ) was used to assess the effect of age: H0 Model: Log( Ig + 1) ~ fixed effect[polynomial(age, 4 degrees)] + random effect[(polynomial(age, 4 degrees) per piglet)] This H0 model fit the effect of age within each piglet (random effect), allowing us to extract the main effect of age regardless of the piglet, akin to the standard dynamics curve of the antibodies. To test for the effect of each parameter (e.g. litter order, colostrum Ig, etc.), two other linear mixed models - a “Main effect” model and an “Interaction” model – were fitted incrementally, each building on top of the default H0 model and compared to it. “Main effect” Model : Log( Ig + 1) ~ fixed effect[polynomial(age, 4 degrees)] + fixed effect[ parameter ] + random effect[(polynomial(age, 4 degrees) per piglet)] Meaning that on top of the main effect of age, a possible main effect of each parameter was also fitted, in order to assess an effect of this parameter on the antibody of interest. This “Main effect” model had no [parameter × age] interaction component, meaning that if there was a main effect, it was modeled to be the same at all ages across the 69-day periods. In contrast, the “Interaction” model assessed the significance of an interaction between the effect of age and the effect of the parameter, in addition to the main effect of the parameter and the effect of age. “Interaction” Model : Log( Ig + 1) ~ fixed effect[polynomial(age, 4 degrees)] + fixed effect[ parameter ] + interaction([polynomial(age, 4 degrees)] x [ parameter ] ) + random effect[(polynomial(age, 4 degrees) per piglet)] The three models were compared to each other with Likelihood ratio test: a significant difference between the “main effect” model and the H0 model indicated that the parameter had an effect across the 69 days periods on the antibody variable of interest. Similarly, a significant difference between the “interaction” model, and either the “main effect” or the H0 models indicated that an interaction between the parameter and the effect of age was supported by the data. Conversely, an absence of difference between the “interaction” model and the “main effect” model indicated that the complexity of an interaction was not supported by the data, hence confirming the conclusion that the main effect did not vary as a function of age. Main > H0 Interaction > H0 Interaction > main Interpretation no no no Parameter had no significant impact on the Ig yes no no Parameter had an effect on the Ig that was independent of age. no yes no Parameter had an effect on the Ig that depended of age, but no “consistent” effect in the whole period. no no yes Unlikely to happen, since one would also expect a significant Interaction > H0 if the Interaction > Main is already significant. yes no yes yes yes no Parameter had an effect on the Ig that was independent of age. no yes yes Parameter had an effect on the Ig that depended of age, but no “consistent” effect in the whole period. yes yes yes Parameter had a main effect in the whole period that did depend on age. Results Study I (farms A-D): Antibody levels in sows and their one-day-old piglets First, we evaluated S. suis -specific and total antibody levels in the serum and colostrum of sows and in the serum of their one-day-old offspring on farms A to D. High variability in serum and colostrum antibody levels was observed between and within the farms, but these differences were not significant (P > 0.05). On farm D, there was a significantly greater level of S. suis- specific serotype 2 antibodies (Ss2Ab) in one-day-old piglets than in piglets from the other farms (Fig. 1 ). In addition, sows from this farm had a greater level of Ss2Ab in serum and colostrum than sows from the other three farms. There were no significant differences in S. suis serotype 9 antibodies (Ss9Ab) between the different farms. Not all piglets on the same farm displayed uniform levels of S. suis -specific antibodies, as both piglets with high (% pos > 1) and low (% pos < 0.5) antibody levels were identified on the same farm. Total levels of IgG, IgA and IgM in colostrum and serum were also determined (Supplementary Fig. 1). All three isotypes of colostrum contain antibodies, with IgG displaying the highest absolute levels. The total IgA, IgG and IgM contents of the colostrum did not differ among the farms (P > 0.05). However, in the serum, higher total IgA levels were detected in sows and piglets from farm A than in those from the other farms (P < 0.05). Study I (farms A-D): correlation between birth parameters and S. suis -specific antibodies in one-day-old piglets Piglet parameters around birth (birth order, colostrum intake, body weight at birth (BWb), weight on day 1 (BW D1) and average daily weight gain (ADG)) and total and specific antibody levels in sow colostrum and serum were analyzed for their associations with the level of S. suis -specific antibodies in one-day-old piglets on farms A to D. There was variability between the farms for the analyzed parameters (Supplementary Fig. 2). However, the average correlation across farms A-D (Fig. 2 ) showed that colostrum intake, birthweight, weight on day 1 and Ss9Ab level in colostrum had a significant positive association (P < 0.05) with the amount of S. suis -specific antibodies in one-day-old piglets. Birth order had a significant negative correlation, and later-born piglets had fewer S. suis -specific antibodies. Study II (farm B): kinetics of antibody levels in the serum of piglets To understand how antibody levels in the serum of piglets change with age, S. suis -specific (IgG + IgM) and total IgA, IgG, and IgM antibody levels were evaluated in piglets from birth until 10 weeks of age. The levels of Ss2Ab and Ss9Ab after birth were greatest after colostrum intake, with high variability among the different litters. During the suckling period, the Ss2Ab and Ss9Ab levels rapidly decreased and reached their lowest points on days 19 and 18, respectively (Fig. 3 A and B, Supplementary Fig. 3A and B). After weaning, the Ss2Ab and Ss9Ab antibody levels increased gradually. However, the overall level remained lower relative to the levels achieved immediately after colostrum intake. The umbilical cord blood samples, which represent the first blood sample of the piglet before colostrum intake, showed lower levels of IgG, IgM and IgA antibodies than did the serum samples collected directly after colostrum intake (Fig. 3 C). Total antibodies, especially IgG, showed high levels directly after colostrum intake, followed by a decrease, with differences in the lowest calculated levels for IgG (29 days), IgM (13 days) and IgA (19 days) (Fig. 3 D). In addition to the antibody kinetics, we evaluated the associations between birth parameters and S. suis- specific antibodies in one-day-old piglets as described in the previous paragraph. In studies I and II, this analysis showed a similar outcome for farm B; only in study II was there a negative correlation between sow serum IgG and the level of S. suis -specific antibodies in one-day-old piglets (Supplementary Fig. 4A). Study II: impact of birth parameters on S. suis -specific antibodies over time Linear mixed models were used to study potential carry-over effects from sow and birth factors until D69 (main effect) with or without a time interaction (variation in main effect over time) for Ss2Ab or Ss9Ab (Fig. 4 and Supplementary Fig. 5). Body weight gain-related parameters around birth (ADG D1, BW D1) and one week after weaning (ADG D34, BW D34) and the level of IgG in sow serum had a significant (P < 0.05) main effect on the kinetics of S. suis -specific antibodies. These findings indicate that the positive or negative effects of these parameters on the level of S. suis antibodies in the serum affect S. suis antibody levels throughout the entire 69-day study period. The ADG D1, BW D1, and sow serum IgG showed a main effect with a time interaction, indicating that the strength of the association of these factors with the level of S. suis -specific antibodies varied at different ages/study time points. For instance, ADG D1 was associated with increased Ss2Ab and Ss9Ab levels in piglet serum throughout the entire study period (Supplementary Fig. 5A). This suggests that piglets with a high increase in BW in the first 24 h after birth will benefit from this increase, as indicated by higher Ss2Ab and Ss9Ab levels in the first 69 days of life. For Ss2Ab, these effects were stable over time (no interaction); for Ss9Ab, there was a significant increase in the effect over time (interaction). Interestingly, most of the colostrum-related parameters showed clear changes over time (a time interaction). More precisely, the positive effect of colostrum antibodies and colostrum uptake seemed to decrease, and the effect at approximately day 69 was even negative (Supplementary Fig. 5D-F). In contrast, for the abovementioned effects of weight and colostrum composition on Ss2Ab and Ss9Ab serum levels in piglets, no parameters seemed to significantly affect IgG serum levels in piglets over time. In summary, weight and growth at D1 have a constant positive impact for the first 69 days of life, while colostrum composition mainly positively affects Ss2Ab/9 levels in the first weeks of life. Study II : Streptococcus suis serotypes 2 and 9 tonsil colonization To evaluate tonsil S. suis colonization in sows and piglets over time, tonsil swabs were taken just before weaning (day 23) in piglets and sows and after weaning in piglets (days 34 and 69). Two out of nine sows (22%) tested positive for S. suis serotype 2, whereas six out of nine sows (67%) tested positive for S. suis serotype 9 (Table 1 and Supplementary Table 3). All serotype 2-positive sows were also positive for serotype 9. One sow was excluded from the analysis because we were unable to obtain a tonsil swab. Nearly all piglets (97%) and all litters tested positive for serotype 9 before weaning (day 23), while for serotype 2, only 26% of the piglets tested positive, and these animals were divided into 4/10 evaluated litters. After weaning, there was an increase in the number of serotype 2-positive piglets and litters, while there was no mixing of the piglets after weaning. On day 69, all the piglets were positive for serotype 9, and 81% of the piglets were positive for serotype 2. For serotype 9, there was no clear difference in the percentage of colonized bacteria before and after weaning. Table 1 qPCR-positive tonsil swabs of S. suis serotypes 2 and 9 from pigs and sows. Sow Piglet Serotype 2 9 2 9 Day (D) D 23 D 23 D 23 D 34 D 69 D 23 D 34 D 69 p/total 2/9 22% 6/9 67% 15/58 26% 22/59 37% 43/54 81% 57/59 97% 56/59 95% 52/54 96% Litters (p) na na 4 8 10 10 10 10 Ten sows were included in study II. From each sow, 6 pigs were selected and included in the study. Tonsillar swabs were taken from the sows and the piglets on the day of weaning (day 23) and from the pigs 34 and 69 days after birth. The swabs were tested for S. suis serotypes 2 and 9 by qPCR. Ct values less than 35 were considered positive (p). Discussion Here, we investigated the transfer of S. suis -specific antibodies from sows to piglets 24 h after birth on four farms, and the MDA decrease and own acquired antibodies increase till 69 days of age, on one of these farms. Ss2Ab and Ss9Ab levels in piglets decreased just before weaning, which is most likely due to the decrease in serum MDA levels, as previously described ( 14 , 15 ). After this time point, there was a gradual increase in S. suis -specific antibodies until the end of the study, which likely represents the production of specific antibodies by the piglets following exposure to the bacterium. In the Netherlands, nearly all sows and piglets are colonized with S. suis , especially with serotype 9 ( 32 , 33 ), as observed in this study. All the piglet tonsils were colonized with S. suis serotype 9 before weaning, while the prevalence of serotype 2 increased after weaning. The piglets most likely received the bacteria from their mother during birth or later via the saliva ( 12 , 13 ). This indicates that all sows, despite vaccination status, will transfer S. suis -specific antibodies to their offspring. In this study, most sows, but not all, were colonized with S. suis. Piglets from negative sows were finally also colonized with S. suis without mixing the litter after weaning. This may indicate that the environment, material and fomites can also play a role in colonization ( 30 , 34 ). The kinetics of the S. suis -specific antibodies in the piglets that we observed in this study were in line with the findings of a recent study on maternal immunity in piglets after sow vaccination with S. suis autogenous bacterins ( 21 ). In that study, S .suis specific antibody levels (IgG + IgM) were greater in seven-day-old piglets from vaccinated sows than in those from nonvaccinated sows. However, the levels rapidly decreased to their lowest point at 18 days of age. This dip was the same as that in the piglets of vaccinated and nonvaccinated sows, indicating that the duration of maternal immunity is not long enough to protect postweaned piglets. Interestingly, S. suis (auto) vaccination of sows can result in a lower disease incidence after weaning in nonvaccinated piglets with or without a clear presence of MDA ( 20 , 22 ). This suggests that in addition to MDA, other parts of the immune system are activated for protection at a later age, e.g., the transfer of pathogen-specific T cells by colostrum ( 35 , 36 ). In two other studies with nonvaccinated control piglets from nonvaccinated sows, the lowest antibody levels were measured at approximately 4–7 weeks of age ( 19 , 22 ), indicating that the onset of antibody production by weaner piglets can occur later than we observed in our study. This means that piglets may be deprived of S. suis -specific antibodies for a prolonged period of time after weaning (3–7 weeks of age), which coincides with the period when clinical problems with S. suis are observed ( 3 ). Several studies with a focus on the transfer of different pathogen-specific MDA from sows to offspring have shown that differences in the duration of persistence of MDA in offspring are mostly associated with the immunization or vaccination status of the sow. For example, Lauritsen et al. ( 37 ) showed that piglets that suckled infected sows were partially protected against infection with Mycoplasma hyosynoviae when challenged at 4.5 weeks of age, with indications that this was related to the MDA in colostrum. MDA persisted in the offspring of sows vaccinated with an inactivated Seneca virus vaccine A (SVA) until 42 days after a single vaccination and 90 days after a booster vaccination ( 38 ). Another study highlighted the importance of MDA for early-life hepatitis E infections and showed that from 5 weeks of age, there is a rapid decline ( 39 ). Overall, MDA play an important role in the prevention of early-life infections, considering that there are differences between pathogens and farm conditions. Furthermore, we determined the total and S. suis -specific antibody levels in one-day-old piglets on four farms and investigated which parameters around birth influenced these levels. One of the farms (Farm D) had more S. suis serotype 2-specific antibodies in both sows and piglets than the other farms. This farm applied autovaccination against serotypes 2 and 9 in sows, while the other farms did not. The immunization of sows or the greater disease pressure on farm D could explain these higher specific antibody levels ( 21 , 40 , 41 ). We showed that a high level of S. suis -specific antibodies in colostrum results in a greater level of S. suis -specific antibodies in the serum of one-day-old piglets. Additionally, colostrum intake, birth weight and 24-h weight gain after birth and birth order are important parameters related to increased levels of S. suis -specific antibodies in the serum of one-day-old piglets ( 42 , 43 ), while total IgG in colostrum seems less important. Several researchers have confirmed that sow and piglet factors at birth have an impact on the condition of the piglets at birth and on survival and growth until the end of the nursery phase. Low birth weight piglets grow more slowly, are more likely to die before weaning ( 44 , 45 ) and have lower colostrum intake and serum IgG levels at 24 hours after birth ( 46 ). Furthermore, birth order significantly affects the condition of the piglets; the later the piglets are born in a litter, the greater the risk of being stillborn or being disadvantaged with regard to behavioral progression, colostrum intake, growth and survival ( 47 ). Therefore, parameters related to colostrum intake, birth order, body weight and body weight gain in the first 24 h after birth are important for total antibody development in piglets and are therefore important for the immune status and development of newborn piglets ( 48 , 49 ). There was high variability among the four farms, and the correlations between birth parameters and piglet S. suis -specific antibody levels were not always consistent. Apparently, farm differences, such as genetic background, parity of sows used, and ambient temperature, may be as relevant as the sow-to-piglet relationship in affecting colostrum quality and immunoglobulin transfer ( 50 – 52 ). Differences in porcine breeds, management and vaccination status on farms A-D could have contributed to this difference. In this study, we evaluated the quantity of total (IgG, IgM and IgA) and S. suis -specific antibodies (IgG/IgM) in colostrum and serum. In both the serum and colostrum, IgG was the most abundant antibody and constituted approximately 90% of the total antibodies in the serum and 80% of the total antibodies in the colostrum. The four farms showed a variation in the levels of total antibodies, and farm A showed consistently higher IgA levels in the serum of piglets and sows, which can be important for mucosal immune responses in neonates ( 25 ). We speculate that on this farm, the higher IgA levels could be related to prior respiratory or intestinal disease, resulting in a more activated mucosal immune system in the sows. It is known that colostrum contains mainly IgG. Within the transition toward milk, the IgG proportion changes dramatically in colostrum: 12 hours after birth, there is a 50% reduction in IgG and an almost null amount of IgG within colostrum/milk by 24 hours ( 50 ). Moreover, the 24-hour weight gain, which is primarily due to colostrum intake, occurs for approximately 93% of the gain within the first 12 hours after the first piglet is born ( 53 ), which enables the piglet to ingest colostrum with a high IgG concentration and start off with high IgG levels in the serum. When piglets grow rapidly, there is a dilution of total serum IgG in the whole body, resulting in a decrease in antibodies, as observed in our study and other studies ( 54 ) ( 46 , 55 ). Studies have shown that high levels of IgG within the first week of life are positively related to the plasma concentration at 28 days of age ( 55 , 56 ). Further research is needed to understand sow-to-colostrum and colostrum-to-piglet Ig transfer and the development of piglets’ own IgG synthesis in relation to immune development. Finally, it is important to mention that the amount of S. suis -specific antibodies was only a minimal proportion of the total antibodies. To measure total IgG antibodies, we diluted the serum 20,000 times, and for the S. suis -specific antibody ELISA, we diluted the serum only 160 times. In addition to the amount of antibodies, their functionality is an important parameter. The capacity of S. suis antibodies to opsonize bacteria in vitro for phagocytes is an important measure of the protective immunity induced by a vaccine ( 21 ). Furthermore, colostrum contains many other components, e.g., lipids, proteins, carbohydrates and leucocytes ( 52 ), which are essential for the growth and survival of piglets ( 57 ). These components can differ between sows, which could lead to differences in the physical condition of the piglets and their growth ( 50 ). Therefore, future studies will benefit from tests assessing the opsonizing capacity of S. suis -specific antibodies and from a more in-depth analysis of other functional components of colostrum, e.g., T cells and cytokines. Conclusions There was a gap in the level of protective S. suis antibodies between 3 and 6 weeks of age. The S. suis -specific serum antibody levels in piglets declined after birth and reached their lowest point before weaning (18–19 days after birth), while self-developed antibodies required 50–60 days to reach levels equivalent to those of the first week of life. The most relevant and predictive factors for S. suis -specific antibody levels in one-day-old piglets were colostrum intake, birth weight, birth order and S. suis antibody level in colostrum, while total sow antibody levels in serum and colostrum were less predictive. In practice, low-birth-weight piglets, late-born piglets and piglets with insufficient colostrum intake should receive extra attention because these piglets have reduced MDA and self-developed antibodies over time. Declarations Ethics approval and consent to participate Farms A-D were consulted for a risk assessment for the presence of specific risk factors related to S. suis infections, including colostrum management practices at the request of the farmer and/or the herds veterinarian. Sampling around birth on farms A-D was performed for diagnostic purposes to evaluate colostrum management practices as a potential risk factor for S. suis -related problems on these farms, and ethics approval was not applicable. Oral consent was obtained from the farmers for the samples collected at their farms. Animal handling, including blood sample collection, was performed by approved veterinarians. The kinetic study on farm B was conducted in accordance with the Dutch animal experimental and ethical requirements, and the project was approved by the Dutch Central Authority for Scientific Procedures on Animals (CCD) (Permit number: AVD4010020198504). Consent for publication Not applicable Funding This research was part of the project “BIT-MAP: Piglets in Transition, Options for Solutions” within the public‒private partnership “One Health for Food” in the Netherlands. This research was cofunded by LTO Nederland, ForFarmers NV, Boehringer Ingelheim, Trouw Nutrition R&D and the Dutch Ministry of Economic Affairs. References Gottschalk M, Segura M. Streptococcosis. Diseases of Swine2019. p. 934-50. Neila-Ibáñez C, Brogaard L, Pailler-García L, Martínez J, Segalés J, Segura M, et al. Piglet innate immune response to Streptococcus suis colonization is modulated by the virulence of the strain. Veterinary research. 2021;52(1):145. Segura M. Streptococcus suis Research: Progress and Challenges. Pathogens. 2020;9(9):707. Okura M, Osaki M, Nomoto R, Arai S, Osawa R, Sekizaki T, et al. Current Taxonomical Situation of Streptococcus suis. Pathogens. 2016;5(3). Wisselink HJ, Smith HE, Stockhofe-Zurwieden N, Peperkamp K, Vecht U. 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Supplementary Files SupplFig.pdf SupplTables.pdf Cite Share Download PDF Status: Published Journal Publication published 07 Feb, 2025 Read the published version in Porcine Health Management → Version 1 posted Editorial decision: Revision requested 09 Sep, 2024 Reviews received at journal 09 Sep, 2024 Reviews received at journal 12 Aug, 2024 Reviewers agreed at journal 12 Aug, 2024 Reviewers agreed at journal 07 Aug, 2024 Reviewers invited by journal 05 Aug, 2024 Editor assigned by journal 22 Jul, 2024 Submission checks completed at journal 22 Jul, 2024 First submitted to journal 19 Jul, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4768277","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":339091593,"identity":"513e4f1e-e556-4097-85bc-6d0b36365bd5","order_by":0,"name":"Sandra Vreman","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0UlEQVRIiWNgGAWjYJACCQSzAkwyHiBByxkIRYIWxjYitMi3nz14u6KGIXF7e3fi58J5hxO3N/AewKvF4ExesuWZYwyJc86c3Sw9c9vhxDkH+BLwa2HIMZNsYGMwlpDI3SDNu+124gwGHgP8Dut/A9TyD6hF/u3m37xziNDCcANoS2Mbg5yEBO82ad4GIrQY3HhjbNnYJyEnwZO7zZrn2H/jGcwEHZZjeLPhmw2PBPvZzbd5atJkZ7D3GD7A6zAIQIpNBmYi1I+CUTAKRsEowA8AbNRG7bZLNKAAAAAASUVORK5CYII=","orcid":"","institution":"Wageningen University \u0026 Research","correspondingAuthor":true,"prefix":"","firstName":"Sandra","middleName":"","lastName":"Vreman","suffix":""},{"id":339091594,"identity":"6d02bcbd-cc86-412c-8d30-66a0a92de717","order_by":1,"name":"Rutger Jansen","email":"","orcid":"","institution":"Boehringer Ingelheim Animal Health Netherlands B.V","correspondingAuthor":false,"prefix":"","firstName":"Rutger","middleName":"","lastName":"Jansen","suffix":""},{"id":339091595,"identity":"48698827-a5dc-42ed-9641-efe4df4bad47","order_by":2,"name":"Mikael Bastian","email":"","orcid":"","institution":"ForFarmers Nederland B.V","correspondingAuthor":false,"prefix":"","firstName":"Mikael","middleName":"","lastName":"Bastian","suffix":""},{"id":339091600,"identity":"5f4cbdf1-7584-4a40-9246-8879b2d4f193","order_by":3,"name":"Patricia Beckers","email":"","orcid":"","institution":"ForFarmers Nederland B.V","correspondingAuthor":false,"prefix":"","firstName":"Patricia","middleName":"","lastName":"Beckers","suffix":""},{"id":339091603,"identity":"f449b19f-cbf6-4cc6-a1a3-df631f41b9ad","order_by":4,"name":"Miriam van Riet","email":"","orcid":"","institution":"ForFarmers Nederland B.V","correspondingAuthor":false,"prefix":"","firstName":"Miriam","middleName":"van","lastName":"Riet","suffix":""},{"id":339091604,"identity":"a3c36746-fba5-40c6-9c94-8c4eadf9d882","order_by":5,"name":"Helmi Fijten","email":"","orcid":"","institution":"Wageningen University \u0026 Research","correspondingAuthor":false,"prefix":"","firstName":"Helmi","middleName":"","lastName":"Fijten","suffix":""},{"id":339091605,"identity":"334dc8d7-b7d2-4bce-a289-b5bea70d53fe","order_by":6,"name":"Jan Fledderus","email":"","orcid":"","institution":"ForFarmers Nederland B.V","correspondingAuthor":false,"prefix":"","firstName":"Jan","middleName":"","lastName":"Fledderus","suffix":""},{"id":339091606,"identity":"e8155b20-563a-4289-83d8-0318144b307d","order_by":7,"name":"Astrid de Greeff","email":"","orcid":"","institution":"Wageningen University \u0026 Research","correspondingAuthor":false,"prefix":"","firstName":"Astrid","middleName":"","lastName":"de Greeff","suffix":""},{"id":339091607,"identity":"8e3f6f87-d9dd-43fd-8bc1-70366d7b0dee","order_by":8,"name":"Helene Winkelman","email":"","orcid":"","institution":"Wageningen University \u0026 Research","correspondingAuthor":false,"prefix":"","firstName":"Helene","middleName":"","lastName":"Winkelman","suffix":""},{"id":339091608,"identity":"1ea71242-14b0-40e8-90c2-592e8546d2dd","order_by":9,"name":"Norbert Stockhofe","email":"","orcid":"","institution":"Wageningen University \u0026 Research","correspondingAuthor":false,"prefix":"","firstName":"Norbert","middleName":"","lastName":"Stockhofe","suffix":""},{"id":339091609,"identity":"5090fd41-f1a1-4f2c-9d58-3d2feaab2c25","order_by":10,"name":"Lluis Faba","email":"","orcid":"","institution":"Trouw Nederland B.V.","correspondingAuthor":false,"prefix":"","firstName":"Lluis","middleName":"","lastName":"Faba","suffix":""},{"id":339091610,"identity":"9ca03249-f5ce-46c9-9f5e-dfd31db5d28b","order_by":11,"name":"Henk J. Wisselink","email":"","orcid":"","institution":"Wageningen University \u0026 Research","correspondingAuthor":false,"prefix":"","firstName":"Henk","middleName":"J.","lastName":"Wisselink","suffix":""},{"id":339091611,"identity":"db1521b6-7716-4d30-937c-6793031e21e0","order_by":12,"name":"Manouk Vrieling","email":"","orcid":"","institution":"Wageningen University \u0026 Research","correspondingAuthor":false,"prefix":"","firstName":"Manouk","middleName":"","lastName":"Vrieling","suffix":""}],"badges":[],"createdAt":"2024-07-19 14:33:44","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4768277/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4768277/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s40813-025-00422-z","type":"published","date":"2025-02-07T15:58:22+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":62777133,"identity":"a347eef6-cdee-43e5-a252-fcc74b2dd771","added_by":"auto","created_at":"2024-08-19 10:50:49","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":158983,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003eStreptococcus suis\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-specific antibodies in sows and piglets after birth.\u003c/strong\u003e On four farms (A to D), \u003cem\u003eS. suis\u003c/em\u003e serotype 2 and 9-specific antibody levels were evaluated by ELISA in the colostrum and serum of sows at farrowing and in the serum samples of their offspring one day after birth. At each farm, four to six sows and five to six piglets per sow were selected. Antibody levels are expressed relative to a positive control serum (% positivity). Significant differences between farms are indicated by asterisks, with ns P ≥ 0.05, * P \u0026lt; 0.05, ** P \u0026lt; 0.01, *** P \u0026lt; 0.001, and **** P \u0026lt; 0.0001. Each dot shows the mean results of duplicate analyses of one animal. The horizontal lines indicate the mean results per farm.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4768277/v1/e6ac99b1b5899d0bfd143951.png"},{"id":62777131,"identity":"096b39d1-1bb6-447f-851a-151767271c2f","added_by":"auto","created_at":"2024-08-19 10:50:49","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":122860,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCorrelation between sow and piglet parameters around birth for total \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eS. suis\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-specific (serotypes 2 and 9) and total antibody levels in piglet serum one day after birth.\u003c/strong\u003e The average Pearson correlation coefficient and STD (between brackets) of the coefficients across the four farms were calculated. A one-sample t test was performed to determine which correlation coefficients were significantly different from zero across the four farms. Significant differences are indicated by asterisks, with t \u0026lt; 0.1, * P \u0026lt; 0.05, ** P \u0026lt; 0.01, and *** P \u0026lt; 0.001. Blue indicates a negative correlation, and green indicates a positive correlation. Body weight at birth (BWb), body weight on day one (BW D1), average daily weight on day one (ADG D1), presence of \u003cem\u003eStreptococcus suis\u003c/em\u003e antibodies serotype 2 (Ss2) and serotype 9 (Ss9), and estimated colostrum intake (23).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4768277/v1/9146a3f18a95e8e4a6422b75.png"},{"id":62777625,"identity":"855cee02-3bb2-4c01-8c63-f9a92c6709bc","added_by":"auto","created_at":"2024-08-19 10:58:49","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":99160,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKinetics of total antibodies and \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eS. suis\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-specific antibodies in pigs from day 1 to day 69.\u003c/strong\u003e Serum samples from\u003cstrong\u003e \u003c/strong\u003esix piglets per litter (ten litters in total) were analyzed by ELISA for \u003cstrong\u003e(A)\u003c/strong\u003e the level of \u003cem\u003eS. suis\u003c/em\u003eserotype 2 and \u003cstrong\u003e(B)\u003c/strong\u003e the level of serotype 9 antibodies expressed relative to the positive control serum (% positivity) \u003cstrong\u003e(C)\u003c/strong\u003eTotal IgG, IgM and IgA antibody levels (mg/ml) were analyzed in the serum of umbilical cord blood (blue) and compared with the serum sample 24 h after colostrum intake (brown); \u003cstrong\u003e(D) \u003c/strong\u003eTotal IgG, IgM and IgA antibody levels (mg/ml) were analyzed in piglet serum; to evaluate the dynamics and time points of the lowest expression of antibodies, the data were scaled.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4768277/v1/b8b5beaee69a81aadb2d20fe.png"},{"id":62777130,"identity":"1f87586a-a1e2-44f6-83ae-a7829584a75d","added_by":"auto","created_at":"2024-08-19 10:50:49","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":72617,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eInfluence of birth factors on \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eS. suis-\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003especific antibody dynamics in piglet serum\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLinear mixed models were used to calculate potential carry-over effects from sow and birth factors until D69 (main effect) with or without a time interaction for Ss2Ab or Ss9Ab. When the average Pearson correlation coefficient at D1 and D69 is strong, the effect is green (positive) or blue (negative). When the correlation is significant but not strong, the effect is not colored; Inter (time interaction), Main (main effect)* P \u0026lt; 0.05, ** P \u0026lt; 0.01, *** P \u0026lt; 0.001; Body weight birth (BWb), body weight day one (BW D1); average daily day one (ADG D1); \u003cem\u003eStreptococcus Suis\u003c/em\u003eantibodies serotype 2 (Ss2) and serotype (Ss9); colostrum intake estimated on calculation Theil (23).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4768277/v1/42fb8a41082daed438abbbf7.png"},{"id":75931442,"identity":"a89deeec-d149-4f3e-90b7-28421cd223b7","added_by":"auto","created_at":"2025-02-10 16:14:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1665766,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4768277/v1/6da78607-328c-424a-b794-3096e920234a.pdf"},{"id":62777136,"identity":"c927cbcc-91c7-4c2a-9315-270dd9b1c5f7","added_by":"auto","created_at":"2024-08-19 10:50:50","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":3667176,"visible":true,"origin":"","legend":"","description":"","filename":"SupplFig.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4768277/v1/ad7ce58f0224c2ae50e8a7f9.pdf"},{"id":62777134,"identity":"8fe2d228-74dc-40e0-b9e7-f5293d82e384","added_by":"auto","created_at":"2024-08-19 10:50:50","extension":"pdf","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":180875,"visible":true,"origin":"","legend":"","description":"","filename":"SupplTables.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4768277/v1/5270667ebb277b43b9ca25db.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The kinetics of maternal and self-developed Streptococcus suis-specific antibodies","fulltext":[{"header":"Background","content":"\u003cp\u003e \u003cem\u003eStreptococcus suis (S. suis)\u003c/em\u003e is an important pathogen in pigs, resulting in infections that lead to decreased performance and increased mortality (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e), with significant consequences for swine health, welfare, and porcine production worldwide. \u003cem\u003eS. suis\u003c/em\u003e infections usually occur in piglets up to 10 weeks of age, especially around weaning, causing meningitis, arthritis, endocarditis, polyserositis with associated lameness, neurologic signs and/or sudden death (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). \u003cem\u003eS. suis\u003c/em\u003e is a very diverse pathogen. Currently, 29 serotypes of \u003cem\u003eS. suis\u003c/em\u003e are recognized based on their capsular polysaccharides (CPSs) surrounding the bacterium (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Although \u003cem\u003eS. suis\u003c/em\u003e serotype 2 is most frequently isolated from clinical cases worldwide, the number of serotype 9 isolates from diseased pigs has increased substantially in Europe (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). Both adult and young pigs can carry \u003cem\u003eS. suis\u003c/em\u003e in the nose, tonsils, and nasopharynx as well as in the genital and gastrointestinal tract (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e), and pigs are often colonized by more than one serotype (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). These carrier pigs are often the source of infection for young sensitive piglets (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e), but sows may also infect their own litters with saliva (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e), and transmission during birth or suckling has been reported (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eA major cause of the high incidence of \u003cem\u003eS. suis\u003c/em\u003e infections postweaning is the immune gap induced by the decrease in maternal-derived antibodies (MDA) after birth and the slow development of acquired antibodies in piglets (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Piglets are born without systemic circulating antibodies, and MDA are only transferred through the uptake of IgG via the intestine from colostrum within the first 24 h after birth (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). These passively acquired antibodies enter the bloodstream of piglets and act as a protective shield throughout the body in the same way as actively produced antibodies (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). Studies have shown that clinical signs of \u003cem\u003eS. suis\u003c/em\u003e infection appear when the level of MDA is low (between 4\u0026ndash;8 weeks of age) (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e) and that the production of \u003cem\u003eS. suis\u003c/em\u003e antibodies slowly increases at the end of the postweaning period, which increases the resistance of pigs to \u003cem\u003eS. suis\u003c/em\u003e infection at a later age (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). In addition, regardless of the antibody level from vaccinated sows or carriers, \u003cem\u003eS. suis\u003c/em\u003e MDA were cleared before weaning (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). More research on the role of \u003cem\u003eS. suis-\u003c/em\u003especific antibodies in sow serum and colostrum and piglet birth parameters, such as colostrum intake and \u003cem\u003eS. suis\u003c/em\u003e-specific antibody levels, can contribute to a better understanding of the lasting clearance of MDA in piglets from birth toward the development of acquired antibodies against \u003cem\u003eS. suis\u003c/em\u003e. In Study I, we evaluated the associations of sow and piglet parameters around birth with total (IgA, IgM, and IgG) and \u003cem\u003eS. suis\u003c/em\u003e-specific (serotypes 2 and 9) antibody levels (IgG\u0026thinsp;+\u0026thinsp;IgM) in one-day-old piglets on four farms in the Netherlands. Subsequently, in Study II, we used one of these farms to evaluate the kinetics of \u003cem\u003eS. suis\u003c/em\u003e serotypes 2 and 9 and total IgA, IgM, and IgG antibodies in piglets from birth to 10 weeks of age. Additionally, from sows and piglets before and after weaning, tonsil swabs were taken to evaluate the \u003cem\u003eS. suis\u003c/em\u003e status (serotypes 2 and 9) and the development of tonsil colonization in piglets.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eExperimental design\u003c/h2\u003e \u003cp\u003eStudy I was a cross-sectional study with samples for diagnostic purposes performed on four farrow-to-finish farms (A to D) in the Netherlands with a high incidence of \u003cem\u003eS. suis\u003c/em\u003e in weaned piglets. The study was performed from 2018\u0026ndash;2019. Within the two years preceding the sampling, the piglets on these farms suffered from clinical disease related to \u003cem\u003eS. suis\u003c/em\u003e serotype 2 and 9 infections. Growth-promoting antibiotics were not used by any of the four farms. On farm D, the sows were vaccinated with an oil-adjuvanted autogenous vaccine (Ceva Biovac) consisting of \u003cem\u003eS. suis\u003c/em\u003e serotype 2 (2 x 2017 brain isolate) and 9 (2017 brain isolate), \u003cem\u003ePasteurella multocida\u003c/em\u003e (1 x 2015 lung isolate) and \u003cem\u003eActinobacillus pleuropneumoniae\u003c/em\u003e (2 x 2016 lung isolate). The animals treated with the autogenous vaccine received a primary vaccination (2.0 ml IM) at 60 days of gestation, which was boosted (2.0 ml IM) at 90 days of gestation. Subsequent boostering was performed at 90 days of each following gestation. Sows on all four farms were fed a commercial pelleted diet and housed in individual farrowing crates compliant with national legislation for the housing of farrowing sows.\u003c/p\u003e \u003cp\u003eFarms were visited for \u003cem\u003eS. suis\u003c/em\u003e problem-related consulting. From each farm, four to six sows that started their farrowing process during the routine consultancy were included in the study. On farms A, B and C, the selection of the desired number of farrowing sows was completed on one day; for farm D, this selection was completed in two days. The sows were observed during farrowing, and no additional help or care was given during birth of the piglets. Within 5 min after birth, the piglets were weighed. The time of birth and body weight at birth (BWb) were recorded. For identification of the piglets, numbered ear tags were used. For study I on farms A-D, a total of 20 sows and 23 piglets were included (Supplementary Table\u0026nbsp;1).\u003c/p\u003e \u003cp\u003eImmediately after the birth of the first piglet (\u0026lt;\u0026thinsp;10 minutes), a colostrum sample was collected from the first three cranial teats of the upper half of the udder of the sow. The sampled teats were cleaned with tissue to remove dust and debris. Teats were milked manually until a volume of 10 ml of colostrum was obtained. The colostrum was refrigerated immediately after collection, aliquoted and stored at -20\u0026deg;C until analysis by ELISA. One day after birth, the piglets were weighed again to determine the 24-hour body weight gain after birth (average daily gain D1 (ADG D1)), and the time of weighing was recorded. The colostrum intake of the piglets was calculated based on the parameters BWb, WG and the duration of colostrum intake (D) using the following equation: -106\u0026thinsp;+\u0026thinsp;2.26 WG\u0026thinsp;+\u0026thinsp;200 BWb\u0026thinsp;+\u0026thinsp;0.111d-1414 WG/D\u0026thinsp;+\u0026thinsp;0.0182 WG/BWb, as previously published (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Blood samples were taken from the selected sows and piglets, and the serum was stored at -20\u0026deg;C until analysis by ELISA.\u003c/p\u003e \u003cp\u003eOne year after the finalization of Study I, Study II started on Farm B. Among the four farms in Study I, this farm was the best equipped to perform a field study with a longer duration and had enough sows for a high likelihood of 10 spontaneous farrows during one day (1165 head sow herds with 55 farrows per weekly batch). In this study, which lasted from March 2020 to May 2020, piglets were born by the natural onset of farrowing. The farm was visited during the day of most natural farrowing (day 115 of gestation, study day 0). Ten sows that were farrowing during that day were included in the study. A total of 149 piglets were delivered to these ten sows. As described previously, all the piglets were weighed directly after birth (BWb), birth order was documented, and a standard ear tag was used for identification. Directly after birth, the umbilical cord was squeezed to obtain a precolostral-fed blood sample of at least 0.5 ml, which was successful for 104 out of the 149 piglets (69.7%). Colostrum samples were collected and processed as described earlier, and the colostrum intake of each pig was calculated.\u003c/p\u003e \u003cp\u003eOn day 1, piglets with birth weights above 1,100 grams were selected to reduce the risk of preweaning mortality (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e), from which a successful umbilical cord blood sample (\u0026gt;\u0026thinsp;0.5 ml whole blood) could be obtained. From these piglets, six piglets per sow were selected for the study, which were equally divided among littermates from the first to the last born piglet. There was no selection for sex. During the suckling period, the piglets were weighed, and blood samples were taken at 1, 6, 13, 20, and 23 days of age and during the postweaning period at 27, 35, 42, 56, and 69 days of age. Pigs were weaned at the age of 23 days, and at weaning, the siblings were kept together in a pen. On day 1, blood samples were also taken from the ten selected sows. The serum of these sows and the serum of the piglets were stored at -20\u0026deg;C until analysis by ELISA. During the study period (from birth until day 69), eight of the 60 piglets (13%) died between day 4 and day 50, which is in line with the average mortality rate (measured from birth until 69 days) on this farm and other farms (\u003cspan additionalcitationids=\"CR27\" citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDue to the fully closed nature of the pens, there was no direct contact between piglets from different litters before and after weaning, limiting the potential for \u003cem\u003eS. suis\u003c/em\u003e to be carried over by direct pig-to-pig contact.\u003c/p\u003e \u003cp\u003eTonsillar samples from the piglets were collected at 23, 34 and 69 days of age and from the sows at weaning. Surgical pliers were used to open the mouths of the pigs. The sows\u0026rsquo; mouths were opened using a metal mouth gag. Tonsillar samples were obtained by rubbing an eSwab\u0026trade; 480CE (Copan Diagnostics, Inc., Carlsbad, CA, USA) on the tonsillar surface for several seconds. The swabs were immediately placed in eSwab\u0026trade; 480CE tubes containing liquid Amies transport medium and transported to the laboratory at ambient temperature, after which the DNA was isolated for qPCR as described below.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eQuantification of porcine IgA, IgM and IgG\u003c/h2\u003e \u003cp\u003eGreiner MICROLON\u0026reg;600 high binding ELISA plates were coated overnight at RT with antibodies against porcine IgA, IgM and IgG diluted in carbonate-bicarbonate buffer (Sigma Aldrich C3041, Saint Louis, MO, USA); see Supplementary Table\u0026nbsp;2 for details about the antibodies and dilutions. Blocking was performed with PBS\u0026thinsp;+\u0026thinsp;1% BSA at pH 7.2 for 1 h at RT. Dilutions of sow and piglet sera, colostrum and umbilical cord blood samples were prepared in PBS and added to the wells. Bound antibodies were detected with the conjugates and dilutions described in using tetramethylbenzidine (TMB) as a substrate (Supplementary Table\u0026nbsp;2). Reactions were stopped after 10\u0026ndash;15 min by the addition of 0.5 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4,\u003c/sub\u003e and extinctions (at 450 nm) were measured on a microplate reader. Primary and secondary antibody incubations were performed for 1 h at RT, and the wells were washed three times with PBS after both incubations. To quantify the amount of IgA, IgM and IgG, a reference pig serum (Bethyl RS10-107, Bethyl Laboratories Inc., Montgomery, Texas, USA) was diluted in PBS to stock solutions of 3.6 \u0026micro;g IgA/ml, 3.5 \u0026micro;g IgM/ml and 3.5 \u0026micro;g IgG/ml. Serial dilutions of the stock solution of the reference serum were measured in duplicate, and a standard curve was fitted using 4-parameter logistics with SoftMax Pro Software. The standard curve was used to interpolate the OD450 values of individual samples to concentrations relative to the standard curve (\u0026micro;g/ml). All sera and other matrices from the A-D farms were analyzed in duplicate, and the mean was used in the calculations. For Study II, the sera and colostrum were analyzed as single samples. The optimal dilutions of the coating antibodies, the matrices, the conjugates and the positive internal control sera were determined during preliminary standardizations.\u003c/p\u003e \u003cp\u003e \u003cb\u003ePorcine antibodies against whole cells of\u003c/b\u003e \u003cb\u003eS. suis\u003c/b\u003e \u003cb\u003eserotypes 2 and 9\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cem\u003eS. suis\u003c/em\u003e serotype 2 strain 10 and serotype 9 strain 8067 were grown overnight in Todd Hewitt broth (THB) at 37\u0026deg;C without shaking. The next day, the bacterial cells were harvested, washed with PBS, and inactivated by treatment with 0.5% formaldehyde for 1 h at room temperature (RT) with intermittent gentle mixing. Inactivated cells were washed and resuspended in PBS. Greiner MICROLON\u0026reg;600 high binding ELISA plates were coated overnight at RT with approximately 1E6 CFU/well of inactivated \u003cem\u003eS. suis\u003c/em\u003e serotype 2 or \u003cem\u003eS. suis\u003c/em\u003e serotype 9 bacteria in PBS. Blocking was performed with PBS\u0026thinsp;+\u0026thinsp;1% BSA at pH 7.2 for 1 h at RT. A series of dilutions of sow and piglet serum, colostrum and umbilical blood samples were prepared in PBS and added to the wells. Bound antibodies were detected with a 1:10,000 dilution of peroxidase (PO)-conjugated anti-porcine-IgL (WBVR, mouse antibody (MAb) clone 27.2.1; (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e)) using tetramethylbenzidine (TMB) as a substrate. Reactions were stopped after 10\u0026ndash;15 min by the addition of 0.5 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4,\u003c/sub\u003e and extinctions (at 450 nm) were measured on a microplate reader. Serum and secondary antibody incubations were performed for 1 h at RT, and the wells were washed three times with PBS after both incubations. Serum samples from pigs that survived an experimental infection with \u003cem\u003eS. suis\u003c/em\u003e serotype 2 strain 10 or \u003cem\u003eS. suis\u003c/em\u003e serotype 9 strain 8067 were used as positive controls for the serotype 2 and serotype 9 ELISAs, respectively. Serial dilutions of the positive control were measured in duplicate, and a standard curve was fitted using 4-parameter logistics with SoftMax Pro Software. The standard curve was used to interpolate the OD450 values of individual samples to concentrations relative to those of the positive control (% positivity). All sera were analyzed in duplicate, and the mean was used in the calculations. The optimal dilutions of the coating antibodies, the matrices, the conjugates and the positive internal control sera were determined during preliminary standardizations.\u003c/p\u003e \u003cp\u003e \u003cb\u003eColonization of tonsils by\u003c/b\u003e \u003cb\u003eS. suis\u003c/b\u003e \u003cb\u003eserotypes 2 and 9\u003c/b\u003e\u003c/p\u003e \u003cp\u003eDNA was isolated from tonsil swabs. For this purpose, the eSwab\u0026trade; 480CE were thawed during 30 minutes, swabs were individually vortexed for 20 seconds and amies fluid was immediately used for isolation. Prior to DNA isolation, the samples were treated with an enzyme mixture to lyse the bacterial cells. Then, 46 \u0026micro;l of lysing mixture containing 20 \u0026micro;l of lysozyme (100 mg/ml), 1 \u0026micro;l of mutanolysin (5000 U/ml) and 25 \u0026micro;l of protein kinase K (600 AU/ml, included in the Qiagen DNeasy Blood \u0026amp; Tissue Kit) was added to 154 \u0026micro;l of the swab sample. The samples were mixed by vortexing and incubated for 30 min at 37\u0026deg;C. Then, 200 \u0026micro;l of AL buffer from the Qiagen Blood and Tissue Kit was added, and the samples were vortexed for 15 seconds and incubated for 30 min at 56\u0026deg;C. Then, 200 \u0026micro;l of 100% ethanol was added, and the samples were vortexed for 15 sec. Purification was continued from step 4 of the Qiagen DNeasy Blood \u0026amp; Tissue Kit manual. Purified DNA was eluted in 30 \u0026micro;l of SuperQ\u0026reg; water.\u003c/p\u003e \u003cp\u003eThe primers and probe sequences specific for the \u003cem\u003ecpsJ\u003c/em\u003e locus of \u003cem\u003eS. suis\u003c/em\u003e serotype 2 (\u003cem\u003ecps2J\u003c/em\u003e) and the \u003cem\u003ecpsH\u003c/em\u003e locus of \u003cem\u003eS. suis\u003c/em\u003e serotype 9 (\u003cem\u003ecps9H)\u003c/em\u003e have been previously described (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). For each \u003cem\u003ecps2J\u003c/em\u003e PCR or \u003cem\u003ecsp9\u003c/em\u003eH PCR a standard curve control was added containing pUC57 plasmid with the specific fragment of the \u003cem\u003ecps2J\u003c/em\u003e of \u003cem\u003ecps9H\u003c/em\u003e gene. Standard curves controls of pUC57-\u003cem\u003ecps2J\u003c/em\u003e and pUC57-\u003cem\u003ecps9H\u003c/em\u003e consist of dilutions 1x10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e -1x10\u003csup\u003e\u0026minus;\u0026thinsp;9\u003c/sup\u003e of a 10\u003csup\u003e0\u003c/sup\u003e stock with a concentration of approximately 3.5x10\u003csup\u003e8\u003c/sup\u003e copies/ul. Standard curves of internal positive controls (IPC) of pUC57-\u003cem\u003ecps2J\u003c/em\u003e-IPC and pUC57-\u003cem\u003ecps9H\u003c/em\u003e-IPC consist of dilutions 1x10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e -1x10\u003csup\u003e\u0026minus;\u0026thinsp;8\u003c/sup\u003e of a 10\u003csup\u003e0\u003c/sup\u003e stock with concentration of approximately 3.5x10\u003csup\u003e8\u003c/sup\u003e copies/ul. The slope for the standard curves should lie between \u0026minus;\u0026thinsp;3.1 and \u0026minus;\u0026thinsp;3.5. Negative controls containing no DNA were also included. Each PCR sample had a final volume of 20 \u0026micro;l and contained: 10 \u0026micro;l of 2X Taqman Fast Universal PCR mix (Thermo Fisher Scientific), 1,8 \u0026micro;l of 10 pmol of forward primer (F-cps2J or F-cps9H), 1,8 \u0026micro;l of 10 pmol of reverse primer (R-cps2J or R-cps9H), 0,25 \u0026micro;l of test probe (FAM-cps 2J or FAM-cps9H), and 0.25 \u0026micro;l of IPC probe (VIC-IPC_cps2J/cps9H). To the experimental samples 2,5 \u0026micro;l of DNA isolated from tonsil swabs was added or 2,5\u0026micro;l of the standard curve dilution or water for the standard and negative controls. One microliter of IPC DNA (1x10\u003csup\u003e\u0026minus;\u0026thinsp;7\u003c/sup\u003e dilution of pUC57 -cps2J-IPC or pUC57- csp9H-IPC) was added to all samples except the IPC standard curve samples. The reactions were supplemented with SuperQ\u0026reg; water (Merck Millipore) up to a volume of 20 \u0026micro;l.\u003c/p\u003e \u003cp\u003ePCR was performed on an ABI 7500 FAST real-time PCR system (Applied Biosystems). The PCR conditions were as follows: 5 min at 95\u0026deg;C, 40X [15 sec at 95\u0026deg;C, 1 min at 60\u0026deg;C], probe detection at FAM/VIC, and a QPCR cutoff of 0.1. The amplification curves were analyzed with the ABI 7500 2.3 software from Applied Biosystems. The uninhibited Ct for 1x10\u003csup\u003e\u0026minus;\u0026thinsp;7\u003c/sup\u003e ng of pUC57- \u003cem\u003ecps2J\u003c/em\u003e DNA and pUC57- \u003cem\u003ecps9H\u003c/em\u003e DNA was between 30 and 31 in both PCRs. Ct values below 35 were considered positive.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe ELISA data were log10 (x\u0026thinsp;+\u0026thinsp;1) transformed to obtain normally distributed data. Comparisons were performed between the four farms using ordinary one-way ANOVA with Tukey\u0026rsquo;s multiple comparisons test (GraphPad Prism 9, USA). Significance across farms was tested with a one-sample t test on the Pearson coefficients to determine whether these were significantly different from 0 (R)(\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLinear-mixed model: (R, lme4 package). For each antibody (Ss2Ab, Ss9Ab and IgG), a default \u0026ldquo;null hypothesis\u0026rdquo; model (referred to below as \u003cem\u003eH0\u003c/em\u003e) was used to assess the effect of age:\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eH0 Model:\u003c/h2\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003eLog( Ig\u0026thinsp;+\u0026thinsp;1)\u0026thinsp;~\u0026thinsp;fixed effect[polynomial(age, 4 degrees)]\u003c/h2\u003e \u003cdiv id=\"Sec8\" class=\"Section4\"\u003e \u003ch2\u003e+ random effect[(polynomial(age, 4 degrees) per piglet)]\u003c/h2\u003e \u003cp\u003eThis H0 model fit the effect of age within each piglet (random effect), allowing us to extract the main effect of age regardless of the piglet, akin to the standard dynamics curve of the antibodies.\u003c/p\u003e \u003cp\u003eTo test for the effect of each parameter (e.g. litter order, colostrum Ig, etc.), two other linear mixed models - a \u0026ldquo;Main effect\u0026rdquo; model and an \u0026ldquo;Interaction\u0026rdquo; model \u0026ndash; were fitted incrementally, each building on top of the default H0 model and compared to it.\u003c/p\u003e \u003cp\u003e \u003cb\u003e\u0026ldquo;Main effect\u0026rdquo; Model\u003c/b\u003e:\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003eLog( Ig\u0026thinsp;+\u0026thinsp;1)\u0026thinsp;~\u0026thinsp;fixed effect[polynomial(age, 4 degrees)]\u003c/h2\u003e \u003cdiv id=\"Sec10\" class=\"Section4\"\u003e \u003ch2\u003e+ fixed effect[ parameter ]\u003c/h2\u003e \u003cp\u003e \u003cem\u003e+ random effect[(polynomial(age, 4 degrees) per piglet)]\u003c/em\u003e \u003c/p\u003e \u003cp\u003eMeaning that on top of the main effect of age, a possible main effect of each parameter was also fitted, in order to assess an effect of this parameter on the antibody of interest. This \u0026ldquo;Main effect\u0026rdquo; model had no [parameter \u0026times; age] interaction component, meaning that if there was a main effect, it was modeled to be the same at all ages across the 69-day periods.\u003c/p\u003e \u003cp\u003eIn contrast, the \u0026ldquo;Interaction\u0026rdquo; model assessed the significance of an interaction between the effect of age and the effect of the parameter, in addition to the main effect of the parameter and the effect of age.\u003c/p\u003e \u003cp\u003e \u003cb\u003e\u0026ldquo;Interaction\u0026rdquo; Model\u003c/b\u003e:\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eLog( Ig\u0026thinsp;+\u0026thinsp;1)\u0026thinsp;~\u0026thinsp;fixed effect[polynomial(age, 4 degrees)]\u003c/h2\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e+ fixed effect[ parameter ]\u003c/h2\u003e \u003cdiv id=\"Sec13\" class=\"Section4\"\u003e \u003ch2\u003e+ interaction([polynomial(age, 4 degrees)] x [ parameter ] )\u003c/h2\u003e \u003cp\u003e \u003cem\u003e+ random effect[(polynomial(age, 4 degrees) per piglet)]\u003c/em\u003e \u003c/p\u003e \u003cp\u003eThe three models were compared to each other with Likelihood ratio test: a significant difference between the \u0026ldquo;main effect\u0026rdquo; model and the H0 model indicated that the parameter had an effect across the 69 days periods on the antibody variable of interest. Similarly, a significant difference between the \u0026ldquo;interaction\u0026rdquo; model, and either the \u0026ldquo;main effect\u0026rdquo; or the H0 models indicated that an interaction between the parameter and the effect of age was supported by the data. Conversely, an absence of difference between the \u0026ldquo;interaction\u0026rdquo; model and the \u0026ldquo;main effect\u0026rdquo; model indicated that the complexity of an interaction was not supported by the data, hence confirming the conclusion that the main effect did not vary as a function of age.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMain\u003c/p\u003e \u003cp\u003e\u0026gt; H0\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInteraction\u003c/p\u003e \u003cp\u003e\u0026gt; H0\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInteraction\u003c/p\u003e \u003cp\u003e\u0026gt; main\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eInterpretation\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eParameter had no significant impact on the Ig\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eParameter had an effect on the Ig that was independent of age.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eParameter had an effect on the Ig that depended of age, but no \u0026ldquo;consistent\u0026rdquo; effect in the whole period.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eUnlikely to happen, since one would also expect a significant Interaction\u0026thinsp;\u0026gt;\u0026thinsp;H0 if the Interaction\u0026thinsp;\u0026gt;\u0026thinsp;Main is already significant.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eParameter had an effect on the Ig that was independent of age.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eParameter had an effect on the Ig that depended of age, but no \u0026ldquo;consistent\u0026rdquo; effect in the whole period.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eParameter had a main effect in the whole period that did depend on age.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\n \u003ch2\u003eStudy I (farms A-D): Antibody levels in sows and their one-day-old piglets\u003c/h2\u003e\n \u003cp\u003eFirst, we evaluated \u003cem\u003eS. suis\u003c/em\u003e-specific and total antibody levels in the serum and colostrum of sows and in the serum of their one-day-old offspring on farms A to D. High variability in serum and colostrum antibody levels was observed between and within the farms, but these differences were not significant (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). On farm D, there was a significantly greater level of \u003cem\u003eS. suis-\u003c/em\u003especific serotype 2 antibodies (Ss2Ab) in one-day-old piglets than in piglets from the other farms (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). In addition, sows from this farm had a greater level of Ss2Ab in serum and colostrum than sows from the other three farms. There were no significant differences in \u003cem\u003eS. suis\u003c/em\u003e serotype 9 antibodies (Ss9Ab) between the different farms. Not all piglets on the same farm displayed uniform levels of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies, as both piglets with high (% pos\u0026thinsp;\u0026gt;\u0026thinsp;1) and low (% pos\u0026thinsp;\u0026lt;\u0026thinsp;0.5) antibody levels were identified on the same farm. Total levels of IgG, IgA and IgM in colostrum and serum were also determined (Supplementary Fig. 1). All three isotypes of colostrum contain antibodies, with IgG displaying the highest absolute levels. The total IgA, IgG and IgM contents of the colostrum did not differ among the farms (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, in the serum, higher total IgA levels were detected in sows and piglets from farm A than in those from the other farms (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eStudy I (farms A-D): correlation between birth parameters and\u003c/strong\u003e \u003cstrong\u003eS. suis\u003c/strong\u003e\u003cstrong\u003e-specific antibodies in one-day-old piglets\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003ePiglet parameters around birth (birth order, colostrum intake, body weight at birth (BWb), weight on day 1 (BW D1) and average daily weight gain (ADG)) and total and specific antibody levels in sow colostrum and serum were analyzed for their associations with the level of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies in one-day-old piglets on farms A to D. There was variability between the farms for the analyzed parameters (Supplementary Fig. 2). However, the average correlation across farms A-D (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e) showed that colostrum intake, birthweight, weight on day 1 and Ss9Ab level in colostrum had a significant positive association (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) with the amount of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies in one-day-old piglets. Birth order had a significant negative correlation, and later-born piglets had fewer \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\n \u003ch2\u003eStudy II (farm B): kinetics of antibody levels in the serum of piglets\u003c/h2\u003e\n \u003cp\u003eTo understand how antibody levels in the serum of piglets change with age, \u003cem\u003eS. suis\u003c/em\u003e-specific (IgG\u0026thinsp;+\u0026thinsp;IgM) and total IgA, IgG, and IgM antibody levels were evaluated in piglets from birth until 10 weeks of age. The levels of Ss2Ab and Ss9Ab after birth were greatest after colostrum intake, with high variability among the different litters. During the suckling period, the Ss2Ab and Ss9Ab levels rapidly decreased and reached their lowest points on days 19 and 18, respectively (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eA and B, Supplementary Fig. 3A and B). After weaning, the Ss2Ab and Ss9Ab antibody levels increased gradually. However, the overall level remained lower relative to the levels achieved immediately after colostrum intake. The umbilical cord blood samples, which represent the first blood sample of the piglet before colostrum intake, showed lower levels of IgG, IgM and IgA antibodies than did the serum samples collected directly after colostrum intake (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eC). Total antibodies, especially IgG, showed high levels directly after colostrum intake, followed by a decrease, with differences in the lowest calculated levels for IgG (29 days), IgM (13 days) and IgA (19 days) (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eD). In addition to the antibody kinetics, we evaluated the associations between birth parameters and \u003cem\u003eS. suis-\u003c/em\u003especific antibodies in one-day-old piglets as described in the previous paragraph. In studies I and II, this analysis showed a similar outcome for farm B; only in study II was there a negative correlation between sow serum IgG and the level of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies in one-day-old piglets (Supplementary Fig. 4A).\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eStudy II: impact of birth parameters on\u003c/strong\u003e \u003cstrong\u003eS. suis\u003c/strong\u003e\u003cstrong\u003e-specific antibodies over time\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eLinear mixed models were used to study potential carry-over effects from sow and birth factors until D69 (main effect) with or without a time interaction (variation in main effect over time) for Ss2Ab or Ss9Ab (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e and Supplementary Fig. 5). Body weight gain-related parameters around birth (ADG D1, BW D1) and one week after weaning (ADG D34, BW D34) and the level of IgG in sow serum had a significant (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) main effect on the kinetics of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies. These findings indicate that the positive or negative effects of these parameters on the level of \u003cem\u003eS. suis\u003c/em\u003e antibodies in the serum affect \u003cem\u003eS. suis\u003c/em\u003e antibody levels throughout the entire 69-day study period. The ADG D1, BW D1, and sow serum IgG showed a main effect with a time interaction, indicating that the strength of the association of these factors with the level of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies varied at different ages/study time points. For instance, ADG D1 was associated with increased Ss2Ab and Ss9Ab levels in piglet serum throughout the entire study period (Supplementary Fig.\u0026nbsp;5A). This suggests that piglets with a high increase in BW in the first 24 h after birth will benefit from this increase, as indicated by higher Ss2Ab and Ss9Ab levels in the first 69 days of life. For Ss2Ab, these effects were stable over time (no interaction); for Ss9Ab, there was a significant increase in the effect over time (interaction).\u003c/p\u003e\n \u003cp\u003eInterestingly, most of the colostrum-related parameters showed clear changes over time (a time interaction). More precisely, the positive effect of colostrum antibodies and colostrum uptake seemed to decrease, and the effect at approximately day 69 was even negative (Supplementary Fig. 5D-F). In contrast, for the abovementioned effects of weight and colostrum composition on Ss2Ab and Ss9Ab serum levels in piglets, no parameters seemed to significantly affect IgG serum levels in piglets over time. In summary, weight and growth at D1 have a constant positive impact for the first 69 days of life, while colostrum composition mainly positively affects Ss2Ab/9 levels in the first weeks of life.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eStudy II\u003c/strong\u003e: \u003cstrong\u003eStreptococcus suis\u003c/strong\u003e \u003cstrong\u003eserotypes 2 and 9 tonsil colonization\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eTo evaluate tonsil \u003cem\u003eS. suis\u003c/em\u003e colonization in sows and piglets over time, tonsil swabs were taken just before weaning (day 23) in piglets and sows and after weaning in piglets (days 34 and 69). Two out of nine sows (22%) tested positive for \u003cem\u003eS. suis\u003c/em\u003e serotype 2, whereas six out of nine sows (67%) tested positive for \u003cem\u003eS. suis\u003c/em\u003e serotype 9 (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e and Supplementary Table 3). All serotype 2-positive sows were also positive for serotype 9. One sow was excluded from the analysis because we were unable to obtain a tonsil swab. Nearly all piglets (97%) and all litters tested positive for serotype 9 before weaning (day 23), while for serotype 2, only 26% of the piglets tested positive, and these animals were divided into 4/10 evaluated litters. After weaning, there was an increase in the number of serotype 2-positive piglets and litters, while there was no mixing of the piglets after weaning. On day 69, all the piglets were positive for serotype 9, and 81% of the piglets were positive for serotype 2. For serotype 9, there was no clear difference in the percentage of colonized bacteria before and after weaning.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003e\u003cstrong\u003eqPCR-positive tonsil swabs of\u003c/strong\u003e \u003cem\u003eS. suis\u003c/em\u003e serotypes 2 and 9 from pigs and sows.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eSow\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"6\"\u003e\n \u003cp\u003ePiglet\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSerotype\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDay (D)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eD 23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eD 23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eD 23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eD 34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eD 69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eD 23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eD 34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eD 69\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ep/total\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2/9\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e22%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6/9\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e67%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15/58\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e26%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22/59\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e37%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e43/54\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e81%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e57/59\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e97%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e56/59\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e95%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e52/54\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e96%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLitters (p)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ena\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ena\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eTen sows were included in study II. From each sow, 6 pigs were selected and included in the study. Tonsillar swabs were taken from the sows and the piglets on the day of weaning (day 23) and from the pigs 34 and 69 days after birth. The swabs were tested for \u003cem\u003eS. suis\u003c/em\u003e serotypes 2 and 9 by qPCR. Ct values less than 35 were considered positive (p).\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eHere, we investigated the transfer of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies from sows to piglets 24 h after birth on four farms, and the MDA decrease and own acquired antibodies increase till 69 days of age, on one of these farms. Ss2Ab and Ss9Ab levels in piglets decreased just before weaning, which is most likely due to the decrease in serum MDA levels, as previously described (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). After this time point, there was a gradual increase in \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies until the end of the study, which likely represents the production of specific antibodies by the piglets following exposure to the bacterium. In the Netherlands, nearly all sows and piglets are colonized with \u003cem\u003eS. suis\u003c/em\u003e, especially with serotype 9 (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e), as observed in this study. All the piglet tonsils were colonized with \u003cem\u003eS. suis\u003c/em\u003e serotype 9 before weaning, while the prevalence of serotype 2 increased after weaning. The piglets most likely received the bacteria from their mother during birth or later via the saliva (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). This indicates that all sows, despite vaccination status, will transfer \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies to their offspring. In this study, most sows, but not all, were colonized with \u003cem\u003eS. suis.\u003c/em\u003e Piglets from negative sows were finally also colonized with \u003cem\u003eS. suis\u003c/em\u003e without mixing the litter after weaning. This may indicate that the environment, material and fomites can also play a role in colonization (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe kinetics of the \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies in the piglets that we observed in this study were in line with the findings of a recent study on maternal immunity in piglets after sow vaccination with \u003cem\u003eS. suis\u003c/em\u003e autogenous bacterins (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). In that study, \u003cem\u003eS .suis\u003c/em\u003e specific antibody levels (IgG\u0026thinsp;+\u0026thinsp;IgM) were greater in seven-day-old piglets from vaccinated sows than in those from nonvaccinated sows. However, the levels rapidly decreased to their lowest point at 18 days of age. This dip was the same as that in the piglets of vaccinated and nonvaccinated sows, indicating that the duration of maternal immunity is not long enough to protect postweaned piglets. Interestingly, \u003cem\u003eS. suis\u003c/em\u003e (auto) vaccination of sows can result in a lower disease incidence after weaning in nonvaccinated piglets with or without a clear presence of MDA (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). This suggests that in addition to MDA, other parts of the immune system are activated for protection at a later age, e.g., the transfer of pathogen-specific T cells by colostrum (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). In two other studies with nonvaccinated control piglets from nonvaccinated sows, the lowest antibody levels were measured at approximately 4\u0026ndash;7 weeks of age (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e), indicating that the onset of antibody production by weaner piglets can occur later than we observed in our study. This means that piglets may be deprived of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies for a prolonged period of time after weaning (3\u0026ndash;7 weeks of age), which coincides with the period when clinical problems with \u003cem\u003eS. suis\u003c/em\u003e are observed (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSeveral studies with a focus on the transfer of different pathogen-specific MDA from sows to offspring have shown that differences in the duration of persistence of MDA in offspring are mostly associated with the immunization or vaccination status of the sow. For example, Lauritsen et al. (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e) showed that piglets that suckled infected sows were partially protected against infection with \u003cem\u003eMycoplasma hyosynoviae\u003c/em\u003e when challenged at 4.5 weeks of age, with indications that this was related to the MDA in colostrum. MDA persisted in the offspring of sows vaccinated with an inactivated Seneca virus vaccine A (SVA) until 42 days after a single vaccination and 90 days after a booster vaccination (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). Another study highlighted the importance of MDA for early-life hepatitis E infections and showed that from 5 weeks of age, there is a rapid decline (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e). Overall, MDA play an important role in the prevention of early-life infections, considering that there are differences between pathogens and farm conditions.\u003c/p\u003e \u003cp\u003eFurthermore, we determined the total and \u003cem\u003eS. suis\u003c/em\u003e-specific antibody levels in one-day-old piglets on four farms and investigated which parameters around birth influenced these levels. One of the farms (Farm D) had more \u003cem\u003eS. suis\u003c/em\u003e serotype 2-specific antibodies in both sows and piglets than the other farms. This farm applied autovaccination against serotypes 2 and 9 in sows, while the other farms did not. The immunization of sows or the greater disease pressure on farm D could explain these higher specific antibody levels (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e). We showed that a high level of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies in colostrum results in a greater level of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies in the serum of one-day-old piglets. Additionally, colostrum intake, birth weight and 24-h weight gain after birth and birth order are important parameters related to increased levels of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies in the serum of one-day-old piglets (\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e), while total IgG in colostrum seems less important.\u003c/p\u003e \u003cp\u003eSeveral researchers have confirmed that sow and piglet factors at birth have an impact on the condition of the piglets at birth and on survival and growth until the end of the nursery phase. Low birth weight piglets grow more slowly, are more likely to die before weaning (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e) and have lower colostrum intake and serum IgG levels at 24 hours after birth (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e). Furthermore, birth order significantly affects the condition of the piglets; the later the piglets are born in a litter, the greater the risk of being stillborn or being disadvantaged with regard to behavioral progression, colostrum intake, growth and survival (\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e). Therefore, parameters related to colostrum intake, birth order, body weight and body weight gain in the first 24 h after birth are important for total antibody development in piglets and are therefore important for the immune status and development of newborn piglets (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThere was high variability among the four farms, and the correlations between birth parameters and piglet \u003cem\u003eS. suis\u003c/em\u003e-specific antibody levels were not always consistent. Apparently, farm differences, such as genetic background, parity of sows used, and ambient temperature, may be as relevant as the sow-to-piglet relationship in affecting colostrum quality and immunoglobulin transfer (\u003cspan additionalcitationids=\"CR51\" citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e). Differences in porcine breeds, management and vaccination status on farms A-D could have contributed to this difference.\u003c/p\u003e \u003cp\u003eIn this study, we evaluated the quantity of total (IgG, IgM and IgA) and \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies (IgG/IgM) in colostrum and serum. In both the serum and colostrum, IgG was the most abundant antibody and constituted approximately 90% of the total antibodies in the serum and 80% of the total antibodies in the colostrum. The four farms showed a variation in the levels of total antibodies, and farm A showed consistently higher IgA levels in the serum of piglets and sows, which can be important for mucosal immune responses in neonates (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). We speculate that on this farm, the higher IgA levels could be related to prior respiratory or intestinal disease, resulting in a more activated mucosal immune system in the sows. It is known that colostrum contains mainly IgG. Within the transition toward milk, the IgG proportion changes dramatically in colostrum: 12 hours after birth, there is a 50% reduction in IgG and an almost null amount of IgG within colostrum/milk by 24 hours (\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e). Moreover, the 24-hour weight gain, which is primarily due to colostrum intake, occurs for approximately 93% of the gain within the first 12 hours after the first piglet is born (\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e), which enables the piglet to ingest colostrum with a high IgG concentration and start off with high IgG levels in the serum. When piglets grow rapidly, there is a dilution of total serum IgG in the whole body, resulting in a decrease in antibodies, as observed in our study and other studies (\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e) (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e). Studies have shown that high levels of IgG within the first week of life are positively related to the plasma concentration at 28 days of age (\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e). Further research is needed to understand sow-to-colostrum and colostrum-to-piglet Ig transfer and the development of piglets\u0026rsquo; own IgG synthesis in relation to immune development.\u003c/p\u003e \u003cp\u003eFinally, it is important to mention that the amount of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies was only a minimal proportion of the total antibodies. To measure total IgG antibodies, we diluted the serum 20,000 times, and for the \u003cem\u003eS. suis\u003c/em\u003e-specific antibody ELISA, we diluted the serum only 160 times. In addition to the amount of antibodies, their functionality is an important parameter. The capacity of \u003cem\u003eS. suis\u003c/em\u003e antibodies to opsonize bacteria \u003cem\u003ein vitro\u003c/em\u003e for phagocytes is an important measure of the protective immunity induced by a vaccine (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). Furthermore, colostrum contains many other components, e.g., lipids, proteins, carbohydrates and leucocytes (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e), which are essential for the growth and survival of piglets (\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e). These components can differ between sows, which could lead to differences in the physical condition of the piglets and their growth (\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e). Therefore, future studies will benefit from tests assessing the opsonizing capacity of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies and from a more in-depth analysis of other functional components of colostrum, e.g., T cells and cytokines.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThere was a gap in the level of protective \u003cem\u003eS. suis\u003c/em\u003e antibodies between 3 and 6 weeks of age. The \u003cem\u003eS. suis\u003c/em\u003e-specific serum antibody levels in piglets declined after birth and reached their lowest point before weaning (18\u0026ndash;19 days after birth), while self-developed antibodies required 50\u0026ndash;60 days to reach levels equivalent to those of the first week of life. The most relevant and predictive factors for \u003cem\u003eS. suis\u003c/em\u003e-specific antibody levels in one-day-old piglets were colostrum intake, birth weight, birth order and \u003cem\u003eS. suis\u003c/em\u003e antibody level in colostrum, while total sow antibody levels in serum and colostrum were less predictive. In practice, low-birth-weight piglets, late-born piglets and piglets with insufficient colostrum intake should receive extra attention because these piglets have reduced MDA and self-developed antibodies over time.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFarms A-D were consulted for a risk assessment for the presence of specific risk factors related to \u003cem\u003eS. suis\u003c/em\u003e infections, including colostrum management practices\u0026nbsp;at the\u0026nbsp;request of the farmer and/or the herds veterinarian. Sampling around birth on\u0026nbsp;farms\u0026nbsp;A-D was performed for diagnostic purposes to evaluate colostrum management practices as a potential risk factor for \u003cem\u003eS. suis\u003c/em\u003e-related problems on these farms,\u0026nbsp;and\u0026nbsp;ethics approval was not applicable. Oral consent was obtained from the farmers for the samples collected at their\u0026nbsp;farms. Animal handling, including blood sample collection, was performed by approved veterinarians. The kinetic study on farm B was conducted in accordance with the Dutch animal experimental and ethical requirements,\u0026nbsp;and the project was approved by the Dutch Central Authority for Scientific Procedures on Animals (CCD) (Permit number: AVD4010020198504).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was part of the project “BIT-MAP: Piglets in Transition, Options for Solutions” within the public‒private partnership “One Health for Food” in the Netherlands. This research was cofunded by LTO Nederland, ForFarmers NV, Boehringer Ingelheim, Trouw Nutrition R\u0026amp;D and the Dutch Ministry of Economic Affairs.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eGottschalk M, Segura M. Streptococcosis. 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Mortality Patterns in a Commercial Wean-To Finish Swine Production System. Veterinary sciences. 2019;6(2):49.\u003c/li\u003e\n \u003cli\u003eVan Zaane D, Hulst MM. Monoclonal antibodies against porcine immunoglobulin isotypes. Veterinary immunology and immunopathology. 1987;16(1-2):23-36.\u003c/li\u003e\n \u003cli\u003eDekker N, Bouma A, Daemen I, Vernooij H, van Leengoed L, Wagenaar JA, et al. Effect of Simultaneous Exposure of Pigs to Streptococcus suis Serotypes 2 and 9 on Their Colonization and Transmission, and on Mortality. Pathogens. 2017;6(4).\u003c/li\u003e\n \u003cli\u003eR. A Language and Environment for Statistical Computing. R Foundation for Statistical Computing. 2021.\u003c/li\u003e\n \u003cli\u003eWillemse N, Howell KJ, Weinert LA, Heuvelink A, Pannekoek Y, Wagenaar JA, et al. An emerging zoonotic clone in the Netherlands provides clues to virulence and zoonotic potential of Streptococcus suis. Scientific reports. 2016;6:28984.\u003c/li\u003e\n \u003cli\u003eSchultsz C, Jansen E, Keijzers W, Rothkamp A, Duim B, Wagenaar JA, et al. Differences in the Population Structure of Invasive Streptococcus suis Strains Isolated from Pigs and from Humans in the Netherlands. PLoS One. 2012;7(5):e33854.\u003c/li\u003e\n \u003cli\u003eBerthelot-H\u0026eacute;rault F, Gottschalk M, Labb\u0026eacute; A, Cariolet R, Kobisch M. Experimental airborne transmission of Streptococcus suis capsular type 2 in pigs. Veterinary microbiology. 2001;82(1):69-80.\u003c/li\u003e\n \u003cli\u003eWilliams P. Immunomodulating effects of intestinal absorbed maternal colostral leukocytes by neonatal pigs. Can J Vet Res. 1993;57:1-8.\u003c/li\u003e\n \u003cli\u003eOgawa S, Okutani M, Tsukahara T, Nakanishi N, Kato Y, Fukuta K, et al. Comparison of gene expression profiles of T cells in porcine colostrum and peripheral blood. Am J Vet Res. 2016;77(9):961-8.\u003c/li\u003e\n \u003cli\u003eLauritsen KT, Hagedorn-Olsen T, Jungersen G, Riber U, Stryhn H, Friis NF, et al. Transfer of maternal immunity to piglets is involved in early protection against Mycoplasma hyosynoviae infection. Veterinary immunology and immunopathology. 2017;183:22-30.\u003c/li\u003e\n \u003cli\u003eYang F, Zhu Z, Liu H, Cao W, Zhang W, Wei T, et al. Evaluation of Antibody Response in Sows after Vaccination with Senecavirus A Vaccine and the Effect of Maternal Antibody Transfer on Antibody Dynamics in Offspring. Vaccines. 2021;9(10).\u003c/li\u003e\n \u003cli\u003eAndraud M, Casas M, Pavio N, Rose N. Early-Life Hepatitis E Infection in Pigs: The Importance of Maternally-Derived Antibodies. PLoS One. 2014;9(8):e105527.\u003c/li\u003e\n \u003cli\u003eB\u0026uuml;ttner N, Beineke A, de Buhr N, Lilienthal S, Merkel J, Waldmann KH, et al. Streptococcus suis serotype 9 bacterin immunogenicity and protective efficacy. Veterinary immunology and immunopathology. 2012;146(3-4):191-200.\u003c/li\u003e\n \u003cli\u003eBaums CG, Kock C, Beineke A, Bennecke K, Goethe R, Schr\u0026ouml;der C, et al. Streptococcus suis bacterin and subunit vaccine immunogenicities and protective efficacies against serotypes 2 and 9. Clinical and vaccine immunology : CVI. 2009;16(2):200-8.\u003c/li\u003e\n \u003cli\u003eCorsaut L, Misener M, Canning P, Beauchamp G, Gottschalk M, Segura M. Field Study on the Immunological Response and Protective Effect of a Licensed Autogenous Vaccine to Control Streptococcus suis Infections in Post-Weaned Piglets. Vaccines. 2020;8(3).\u003c/li\u003e\n \u003cli\u003eLapointe L, D\u0026apos;Allaire S, Lebrun A, Lacouture S, Gottschalk M. Antibody response to an autogenous vaccine and serologic profile for Streptococcus suis capsular type 1/2. Can J Vet Res. 2002;66(1):8-14.\u003c/li\u003e\n \u003cli\u003eFix JS, Cassady JP, Holl JW, Herring WO, Culbertson MS, See MT. Effect of piglet birth weight on survival and quality of commercial market swine. Livestock Science. 2010;132(1):98-106.\u003c/li\u003e\n \u003cli\u003eCabrera RA, Lin X, Campbell JM, Moeser AJ, Odle J. Influence of birth order, birth weight, colostrum and serum immunoglobulin G on neonatal piglet survival. Journal of Animal Science and Biotechnology. 2012;3(1):42.\u003c/li\u003e\n \u003cli\u003eFerrari CV, Sbardella PE, Bernardi ML, Coutinho ML, Vaz IS, Wentz I, et al. Effect of birth weight and colostrum intake on mortality and performance of piglets after cross-fostering in sows of different parities. Prev Vet Med. 2014;114(3):259-66.\u003c/li\u003e\n \u003cli\u003eLangendijk P, Plush K. Parturition and Its Relationship with Stillbirths and Asphyxiated Piglets. Animals. 2019;9(11):885.\u003c/li\u003e\n \u003cli\u003eButler JE, Sun J, Wertz N, Sinkora M. Antibody repertoire development in swine. Developmental and comparative immunology. 2006;30(1-2):199-221.\u003c/li\u003e\n \u003cli\u003ePoonsuk K, Zimmerman J. Historical and contemporary aspects of maternal immunity in swine. Animal health research reviews. 2018;19(1):31-45.\u003c/li\u003e\n \u003cli\u003eHurley WL. 9. Composition of sow colostrum and milk. The gestating and lactating sow. p. 193-230.\u003c/li\u003e\n \u003cli\u003eRooke JA, Bland IM. The acquisition of passive immunity in the new-born piglet. Livestock Production Science. 2002;78(1):13-23.\u003c/li\u003e\n \u003cli\u003eForner R, Bombassaro G, Bellaver FV, Maciag S, Fonseca FN, Gava D, et al. Distribution difference of colostrum-derived B and T cells subsets in gilts and sows. PLoS One. 2021;16(5):e0249366.\u003c/li\u003e\n \u003cli\u003eKrogh U. Mammary plasma flow, mammary nutrient uptake and the production of colostrum and milk in highprolific sows: Aarhus University, Denmark; 2016.\u003c/li\u003e\n \u003cli\u003eRamirez CG, Miller ER, Ullrey DE, Hoefer JA. Swine Hematology from Birth to Maturity. III. Blood Volume of the Nursing Pig. J Anim Sci. 1963;22(4):1068-74.\u003c/li\u003e\n \u003cli\u003eRooke JA, Carranca C, Bland IM, Sinclair AG, Ewen M, Bland VC, et al. Relationships between passive absorption of immunoglobulin G by the piglet and plasma concentrations of immunoglobulin G at weaning. Livestock Production Science. 2003;81(2):223-34.\u003c/li\u003e\n \u003cli\u003eMarkowska-Daniel I, Pomorska-M\u0026oacute;l M, Pejsak Z. Dynamic changes of immunoglobulin concentrations in pig colostrum and serum around parturition. Pol J Vet Sci. 2010;13(1):21-7.\u003c/li\u003e\n \u003cli\u003eZhang S, Chen F, Zhang Y, Lv Y, Heng J, Min T, et al. Recent progress of porcine milk components and mammary gland function. J Anim Sci Biotechnol. 2018;9:77.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"porcine-health-management","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"phmj","sideBox":"Learn more about [Porcine Health Management](http://porcinehealthmanagement.biomedcentral.com/)","snPcode":"40813","submissionUrl":"https://submission.nature.com/new-submission/40813/3","title":"Porcine Health Management","twitterHandle":"@animalplantsci","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Streptococcus suis, piglet, sow, antibodies, colostrum, immune gap, maternal-derived antibodies (MDA), field study","lastPublishedDoi":"10.21203/rs.3.rs-4768277/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4768277/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003e\u003cem\u003eStreptococcus suis (S. suis)\u003c/em\u003e infections are responsible for a large disease burden in piglets after weaning, compromising animal welfare and increasing antibiotic use. The immune gap caused by decreased maternal-derived antibodies (MDA) and insufficient acquired antibodies in weaned pigs could be a key factor for increased susceptibility to \u003cem\u003eS. suis\u003c/em\u003e infections. To better understand this, two studies were performed. Study I evaluated the associations between sow antibodies in colostrum and serum, birth parameters (e.g., birth weight, colostrum intake and piglet growth) and the levels of \u003cem\u003eS. suis\u003c/em\u003e-specific (serotypes 2 and 9) antibodies in one-day-old piglets from four farms. Subsequently, Study II used one of these farms to evaluate \u003cem\u003eS. suis\u003c/em\u003e-specific and total antibody kinetics in piglets (10 litters with 6 selected piglets per litter, total n=60) from birth until10 weeks of age. Additionally, tonsil swabs from sows and piglets were taken to evaluate the \u003cem\u003eS. suis\u003c/em\u003e tonsillar carrier status (serotypes 2 and 9) before and after weaning.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eHigh variability in serum and colostrum antibody levels was observed between and within the four farms (study I). In Study II, there was a decrease in \u003cem\u003eS. suis-\u003c/em\u003especific MDA after 24 hours of age, with the lowest level occurring at approximately 18/19 days of age. Afterwards, there was an increase in specific antibodies, most likely due to acquired immunity. Colostrum intake, birth weight and 24-h weight gain after birth were important parameters that were positively associated with \u003cem\u003eS. suis\u003c/em\u003e antibody levels in piglets after birth but also affected these antibody levels at a later age. All the piglet tonsils were colonized with \u003cem\u003eS. suis\u003c/em\u003eserotype 9 before weaning, while the prevalence of serotype 2 increased after weaning.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e The lowest level of \u003cem\u003eS. suis\u003c/em\u003e-specific antibodies was detected just before weaning, which contributes to piglet susceptibility to \u003cem\u003eS. suis\u003c/em\u003e infections. Farmers and veterinarians should focus on piglets with low birth weights, late-born piglets, and/or piglets with low colostrum intake because these parameters reduce both the \u003cem\u003eS. suis\u003c/em\u003e-specific MDA preweaning and the specific antibodies acquired postweaning.\u003c/p\u003e","manuscriptTitle":"The kinetics of maternal and self-developed Streptococcus suis-specific antibodies","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-19 10:50:45","doi":"10.21203/rs.3.rs-4768277/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-09-09T10:43:05+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-09T10:12:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-12T10:20:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"41812132660167817850247681669121172569","date":"2024-08-12T06:24:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"133806502753742015206857163213154646562","date":"2024-08-07T06:28:14+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-08-05T12:21:14+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-23T01:17:58+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-23T01:17:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"Porcine Health Management","date":"2024-07-19T14:32:25+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"porcine-health-management","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"phmj","sideBox":"Learn more about [Porcine Health Management](http://porcinehealthmanagement.biomedcentral.com/)","snPcode":"40813","submissionUrl":"https://submission.nature.com/new-submission/40813/3","title":"Porcine Health Management","twitterHandle":"@animalplantsci","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"325a4bed-8cc8-4955-943e-f70441691aff","owner":[],"postedDate":"August 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-02-10T16:13:17+00:00","versionOfRecord":{"articleIdentity":"rs-4768277","link":"https://doi.org/10.1186/s40813-025-00422-z","journal":{"identity":"porcine-health-management","isVorOnly":false,"title":"Porcine Health Management"},"publishedOn":"2025-02-07 15:58:22","publishedOnDateReadable":"February 7th, 2025"},"versionCreatedAt":"2024-08-19 10:50:45","video":"","vorDoi":"10.1186/s40813-025-00422-z","vorDoiUrl":"https://doi.org/10.1186/s40813-025-00422-z","workflowStages":[]},"version":"v1","identity":"rs-4768277","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4768277","identity":"rs-4768277","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}