Validation of Polymorphisms Associated with the Immune Response After Vaccination Against Porcine Reproductive and Respiratory Syndrome Virus in Replacement Yorkshire Gilts

Porcine respiratory and reproductive syndrome (PRRS) is a viral disease that affects health and profitability in swine farms, largely due to a high variation in vaccination response. The objective was to discover and validate molecular markers associated with the antibody response in gilts after vaccination against PRRS virus. The study included one hundred (n=100) 6-month-old gilts from the breed Yorkshire that were PRRS virus-negative. After 7 days of acclimation period, all gilts were vaccinated with a modified live PRRS virus (day 0). Blood samples collected on day 21 were used to evaluate the antibody response, as the sample-to-positive (S/P) ratio, to PRRS virus after vaccination. DNA was extracted and genotyped using a low-density chip including 10,000 single nucleotide polymorphisms (SNPs). A genome-wide association study (GWAS) was performed to discover candidate SNPs associated with the S/P ratio, which were validated in two independent gilt populations (n=226). The SNPs rs80904326, rs80896559 and rs81358818 in the genes RNF144B, XKR9 and BMAL1, respectively, were associated (p < 0.01) with the S/P ratio and exhibited an additive effect. In conclusion, three SNPs are proposed as candidate markers for an improved immune response to vaccination against PRRS virus and may be useful in genetic selection programs.