First-in-Human Dengue Serotype 4 Live Virus Human Challenge: A Phase 1 Dose Optimization and Homologous Rechallenge Study

First-in-Human Dengue Serotype 4 Live Virus Human Challenge: A Phase 1 Dose Optimization and Homologous Rechallenge Study | 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 Article First-in-Human Dengue Serotype 4 Live Virus Human Challenge: A Phase 1 Dose Optimization and Homologous Rechallenge Study Joel Chua, Angie Price, Salma Sharaf, Sigrid Camacho Ortega, Paula Bernal, and 10 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7947800/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Dengue Live Virus Human Challenges (LVHC) are critically needed in dengue vaccine and pharmacologic development to down-select candidates and provides a useful platform for understanding viral-host immunology in a controlled setting. We conducted a first-in-human phase 1 open label study evaluating the safety and optimized dose of an underattenuated dengue virus serotype-4-LVHC (DENV-4-LVHC) strain H-241. The study was divided into a dose optimization study followed by a homologous rechallenge substudy. Fourteen healthy adult participants were enrolled and challenged with a subcutaneous dose of DENV-4-LVHC. All 14 developed viremia and symptoms consistent with self-limited, mild-moderate dengue. Six participants were rechallenged using the optimized dose 1 year after primary challenge, and none developed detectable dengue. Robust antibody responses, plasmablast expansion, and antiviral gene upregulation were seen during primary infection but not after rechallenge. No severe dengue, need for inpatient observation, or dengue challenge-related serious adverse events were observed. DENV-4-LVHC was found to be safe and highly predictable for use in future studies to evaluate vaccine and therapeutic candidates. Immunity from prior DENV-4-LVHC infection conferred protection following homologous rechallenge one year after primary exposure. ClinicalTrial.gov identifier: NCT05268302. Health sciences/Diseases/Infectious diseases/Viral infection Biological sciences/Immunology/Infectious diseases/Viral infection Health sciences/Medical research/Clinical trial design/Clinical trials/Phase I trials Health sciences/Pathogenesis/Immunopathogenesis/Adaptive immunity/Humoral immunity/Antibodies Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Full Text Additional Declarations There is NO Competing Interest. Supplementary Files nrreportingsummaryNMEDA146514.pdf Reporting Summary CONSORT2025DHIM4NMEDA146514v1.0.docx CONSORT Checklist SAPDHIM4version12JUN2024.pdf Statistical Analysis Plan SupplementalAppendixDHIM4NMEDA146514v1.0Oct242025.docx Supplemental Appendix Protocolv6.0DHIM4Homologous17April2023.pdf Study Protocol nreditorialpolicychecklistNMEDA146514.pdf Editorial Policy Checklist Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. 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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-7947800","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":537671004,"identity":"3788c654-a7de-4b96-8b99-9d68c66ab62f","order_by":0,"name":"Joel Chua","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+UlEQVRIiWNgGAWjYBACxgYeIFkhkQATkAFiAwYGNkJaziC08BDUAlbD2MZAghbm9rPHJH7Os8gzOMBjuuHnnsM8/LObNzB8KDuM22E9eWmSvdskioFazG72PDvMI3HnWAHjjHN4tMzgMZPg3SaROLOBx+wGz4HDPAw3cgyYedvwa5H8Owei5eYfoBZ5kJa/BLRI8zZIJPYz8JjdBtliANLCiE9LT46xtcwxoBZmtrLbMgfSeQxvpBUc7DmXjlOLYfsZw5tvauoS29ibt918c8BaTu5G8sYHP8qscWtpgLGYwWQzmDyAUz0QyKPx6/ApHgWjYBSMghEKAOZkVXfp3Nc4AAAAAElFTkSuQmCC","orcid":"","institution":"Institute of Human Virology, University of Maryland School of Medicine","correspondingAuthor":true,"prefix":"","firstName":"Joel","middleName":"","lastName":"Chua","suffix":""},{"id":537671005,"identity":"9e6aef74-b0ca-453e-9c20-cbc0ddf14199","order_by":1,"name":"Angie Price","email":"","orcid":"","institution":"Institute of Human Virology, University of Maryland School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Angie","middleName":"","lastName":"Price","suffix":""},{"id":537671006,"identity":"fea18eb9-3850-4132-b257-7689a0cd2b0c","order_by":2,"name":"Salma Sharaf","email":"","orcid":"","institution":"Institute of Human Virology, University of Maryland School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Salma","middleName":"","lastName":"Sharaf","suffix":""},{"id":537671007,"identity":"79c6ed53-0390-4078-8595-f305d75ceb16","order_by":3,"name":"Sigrid Camacho Ortega","email":"","orcid":"","institution":"Institute of Human Virology, University of Maryland School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Sigrid","middleName":"Camacho","lastName":"Ortega","suffix":""},{"id":537671008,"identity":"fc8e9458-2184-474d-a765-9627d77c136c","order_by":4,"name":"Paula Bernal","email":"","orcid":"https://orcid.org/0009-0002-2421-302X","institution":"University of Maryland School of Medicine, Center for Vaccine Development and Global Health","correspondingAuthor":false,"prefix":"","firstName":"Paula","middleName":"","lastName":"Bernal","suffix":""},{"id":537671009,"identity":"24abece3-10bf-4bd3-af6e-4a81aa910faf","order_by":5,"name":"Lauryn Butler","email":"","orcid":"","institution":"Center for Vaccine Development and Global Health, University of Maryland School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Lauryn","middleName":"","lastName":"Butler","suffix":""},{"id":537671010,"identity":"309a1946-6d5e-49c9-a834-547ebdb84682","order_by":6,"name":"Sudhaunshu Joshi","email":"","orcid":"","institution":"University of Maryland School of Medicine, Center for Vaccine Development and Global Health","correspondingAuthor":false,"prefix":"","firstName":"Sudhaunshu","middleName":"","lastName":"Joshi","suffix":""},{"id":537671011,"identity":"26b51e9a-9a45-4c3d-af20-885c4f3ff668","order_by":7,"name":"A. Rachida Koudjra","email":"","orcid":"","institution":"Center for Vaccine Development and Global Health, University of Maryland School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"A.","middleName":"Rachida","lastName":"Koudjra","suffix":""},{"id":537671012,"identity":"4e7c2825-40cc-4d2d-8612-19f42208b794","order_by":8,"name":"Céline S. Hardy","email":"","orcid":"","institution":"Department of Microbiology and Immunology, State University of New York Update Medical University","correspondingAuthor":false,"prefix":"","firstName":"Céline","middleName":"S.","lastName":"Hardy","suffix":""},{"id":537671013,"identity":"4a25c5dd-d988-4df8-b49f-226fa5c5c23e","order_by":9,"name":"Jeffrey Currier","email":"","orcid":"","institution":"Walter Reed Army Institute of Research","correspondingAuthor":false,"prefix":"","firstName":"Jeffrey","middleName":"","lastName":"Currier","suffix":""},{"id":537671014,"identity":"decb5afb-3e14-4dbb-854a-bab47316b132","order_by":10,"name":"Adam Waickman","email":"","orcid":"https://orcid.org/0000-0002-4536-6714","institution":"SUNY Upstate Medical University","correspondingAuthor":false,"prefix":"","firstName":"Adam","middleName":"","lastName":"Waickman","suffix":""},{"id":537671015,"identity":"cef55885-0787-4fe8-8c38-70337607426d","order_by":11,"name":"Cristiana Cairo","email":"","orcid":"","institution":"Department of Microbiology and Immunology, University of Maryland School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Cristiana","middleName":"","lastName":"Cairo","suffix":""},{"id":537671016,"identity":"78d91145-14c4-441d-ab96-4834418186c3","order_by":12,"name":"Heather Friberg","email":"","orcid":"","institution":"Walter Reed Army Institute of Research","correspondingAuthor":false,"prefix":"","firstName":"Heather","middleName":"","lastName":"Friberg","suffix":""},{"id":537671017,"identity":"eeefbcd1-ea07-4766-9c60-c98c9b5d1f13","order_by":13,"name":"Robert Edelman","email":"","orcid":"","institution":"University of Maryland School of Medicine, Center for Vaccine Development and Global Health","correspondingAuthor":false,"prefix":"","firstName":"Robert","middleName":"","lastName":"Edelman","suffix":""},{"id":537671018,"identity":"f9d54ef3-2fc0-46b7-9529-d351d44e5a68","order_by":14,"name":"Kirsten Lyke","email":"","orcid":"https://orcid.org/0000-0002-4966-0830","institution":"University of Maryland","correspondingAuthor":false,"prefix":"","firstName":"Kirsten","middleName":"","lastName":"Lyke","suffix":""}],"badges":[],"createdAt":"2025-10-27 10:54:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7947800/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7947800/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":94920062,"identity":"06a0f3bf-80f3-44ad-9e7f-5394fcac5422","added_by":"auto","created_at":"2025-11-01 13:20:33","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":123290,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 1: Dengue signs and symptoms after primary DENV-4 infection (N = 14).\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePanel \u003cstrong\u003eA\u003c/strong\u003edepicts the gradation (mild, moderate and severe) of dengue solicited symptoms with fatigue and rashes being the most common and Panel \u003cstrong\u003eB\u003c/strong\u003e depicts a typical, total body (Grade severe) erythematous nonpruritic nontender blanching rash. Panel \u003cstrong\u003eC\u003c/strong\u003e to\u003cstrong\u003e E \u003c/strong\u003eillustrates select laboratory tests known to be affected by dengue infection: \u003cstrong\u003e(C)\u003c/strong\u003e WBC counts collectively nadirs at about day 10 post-challenge and returns to baseline by day 28; \u003cstrong\u003e(D)\u003c/strong\u003eTransient mild to moderate ALT elevation is observed in 3 participants (3 of 14, 21%); and \u003cstrong\u003e(E) \u003c/strong\u003enone developed thrombocytopenia.\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/071ee8b662d0a1149780f327.png"},{"id":94987116,"identity":"4b313abc-74ba-4907-ad3b-ad8d63ca90d6","added_by":"auto","created_at":"2025-11-03 07:01:16","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":89778,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 2:\u003c/strong\u003e \u003cstrong\u003eKinetics of dengue virus RNAemia, viremia, and NS1.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePanel \u003cstrong\u003eA\u003c/strong\u003e depicts dengue RNAemia (measured directly ex vivo; upper panel) and infectious viremia (measured after cell culture amplification; middle panel) curves following primary DENV-4 challenge. All 14 participants had quantifiable, infectious viruses by plaque assay with an average onset of detection 2 days later than RNAemia, and average peak viremia 2.8 log\u003csub\u003e10\u003c/sub\u003e lower than RNAemia (lower panel). The infectious viremia AUC fit entirely within the RNAemia AUC. One participant (PTID-4020; olive green lines) had a slightly delayed onset of RNAemia and viremia compared to the others. No detectable RNAemia, viremia, or NS1 were observed during the homologous rechallenge (data not shown). Panel \u003cstrong\u003eB\u003c/strong\u003e depicts NS1 levels for those undergoing primary infection (orange) and rechallenge (purple). Panel \u003cstrong\u003eC\u003c/strong\u003e compares onset of RNAemia, viremia, and NS1 after primary DENV-4 infection, which shows a significantly earlier onset of RNAemia compared to NS1 levels (p=0.0023) and viremia (p\u0026lt;0.0001). Legend: AUC – area under the curve; GE/mL – genomic equivalence per milliliter; PFU/mL – plaque forming units per milliliter; NS1 – dengue virus nonstructural protein 1.\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/1bf20d8ba6e9f3084584592c.png"},{"id":94920063,"identity":"b8997aed-b3bd-4c92-ac98-15099a34cb44","added_by":"auto","created_at":"2025-11-01 13:20:33","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":65552,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3:\u003c/strong\u003e \u003cstrong\u003eAntibody responses following primary and homologous challenges.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePanel \u003cstrong\u003eA\u003c/strong\u003e illustrates microneutralization (MN\u003csub\u003e50\u003c/sub\u003e) titers following primary infection (magenta) and homologous rechallenge (purple). All 14 participants had robust MN\u003csub\u003e50\u003c/sub\u003e titers against DENV-4 following primary DENV-4 infection, with MN\u003csub\u003e50\u003c/sub\u003e titers plateauing after D28 and maintained one year later (the latter, only shown for the 6 rechallenge participants). No significant MN\u003csub\u003e50\u003c/sub\u003e titer changes were observed after homologous rechallenge. Panel \u003cstrong\u003eB\u003c/strong\u003e illustrates dengue-specific IgM (red), IgG (orange), and IgA (teal) titers by viral capture ELISA following primary infection (magenta arrowhead) and after homologous rechallenge (purple arrowhead). Robust IgM and IgG responses in all participants, and IgA in 12 of 14 participants, occurred following primary DENV-4 infection. Panel \u003cstrong\u003eC\u003c/strong\u003e line charts depict the proportion of plasmablasts expressing different surface immunoglobulin isotypes (IgM, IgG, IgA from left to right) at the various time points before and after primary infection (Day 0; magenta arrowhead) and homologous rechallenge (Day 360; purple arrowhead). Statistical analyses were performed using the Kruskal-Wallis test: * p\u0026lt;0.05; ** p\u0026lt;0.01; *** p\u0026lt;0.001\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/3a6cc849a9617fef60341945.png"},{"id":94920066,"identity":"aef4ddda-8703-4f87-9517-b53d4cee8464","added_by":"auto","created_at":"2025-11-01 13:20:33","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":208068,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 4:\u003c/strong\u003e \u003cstrong\u003ePlasmablast proportions increase after primary infection but not after homologous rechallenge.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLongitudinal PBMC specimens were thawed and stained with a panel of 29 antibodies against surface markers representing various subsets of B cells. Pre refers to pre-challenge; D4 to RNAemia onset; D14 to RNAemia cessation. (\u003cstrong\u003eA\u003c/strong\u003e) The pseudocolor plots display the proportion of plasmablasts before (pre) and after primary infection for a representative study participant. (\u003cstrong\u003eB\u003c/strong\u003e) The plots summarize plasmablast proportions before and after primary infection and rechallenge for all participants tested. (\u003cstrong\u003eC\u003c/strong\u003e) The UMAPs show the localization of the plasmablast population (right plot) relative to the expression of CD38 (middle plot). (\u003cstrong\u003eD\u003c/strong\u003e) A manually drawn plasmablast gate (red circle) shows the dynamics of the population over time after primary infection (top panel) and homologous rechallenge (lower panel). UMAPs display the results of the dimensionality reduction for B cells in the concatenated file (with normalized samples for all donors) for each time point before (pre) and after primary challenge and rechallenge. The red gate identifies the plasmablast cluster. Statistical analyses were performed with Kruskal-Wallis test: * p\u0026lt;0.05; ** p\u0026lt;0.01; *** p\u0026lt;0.001.\u003cstrong\u003e \u003c/strong\u003eAdditionally, select markers on plasmablasts are modulated following primary infection but not after homologous rechallenge: (\u003cstrong\u003eE\u003c/strong\u003e) The overlays compare expression patterns of select markers between plasmablasts (PB, in red) and non-plasmablasts (Non-PB, in blue) B cells at baseline (before primary infection). (\u003cstrong\u003eF\u003c/strong\u003e) The line graphs summarize the proportion of CD71+ plasmablasts before and after primary infection (left panel) and rechallenge (right panel). (\u003cstrong\u003eG\u003c/strong\u003e) The line graphs summarize the proportion of CD21+ plasmablasts before and after primary infection (left panel) and rechallenge (right panel). Statistical analyses were performed with an ANOVA test: ** p\u0026lt;0.01; *** p\u0026lt;0.001; **** p\u0026lt;0.0001.\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/1b07ec86d2a1486a3bdb7497.png"},{"id":94920068,"identity":"f8e1bb7b-07ef-4024-9417-f4e9356a85e0","added_by":"auto","created_at":"2025-11-01 13:20:33","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":105862,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 5: Gene expression analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA\u003c/strong\u003e) The kinetics of a previously defined inflammatory gene module (transcription score) across all nine study participants tested following primary DENV-4-LVHC infection and rechallenge. Symbol and line color corresponds to participant ID. \u003cstrong\u003eB\u003c/strong\u003e) Identification and quantification of unique IGH clones are shown across 8 study participants and timepoints from baseline (day 0) to day 28 post infection from unenriched RNAseq data using MiXCR. \u003cstrong\u003eC\u003c/strong\u003e) Volcano plots show differential gene expression for day 0 versus day 2, day 0 versus day 4, day 0 versus day 6, day 0 versus day 8, day 0 versus day 10, day 0 versus day 12, day 0 versus day 14, and day 0 versus day 28 post-infection with select statistically and biologically significant genes highlighted. Genes with a log\u003csub\u003e2\u003c/sub\u003e fold change \u0026gt;1 and adjusted P value \u0026lt;0.05 were considered significant.\u003c/p\u003e","description":"","filename":"Fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/280c84d6b1a1d8ca2142f148.png"},{"id":97668655,"identity":"9e87d71b-9fd1-4802-9c24-f0f5c03d0850","added_by":"auto","created_at":"2025-12-08 09:25:58","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":895469,"visible":true,"origin":"","legend":"","description":"","filename":"DHIM4ManuscriptNMEDA146514v1.0Oct242025.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1_covered_ed8fbf9c-b0c2-4a08-8d2d-74153d60c514.pdf"},{"id":94920067,"identity":"c61b5199-d7ef-4785-903a-3d5f0cd443fb","added_by":"auto","created_at":"2025-11-01 13:20:33","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1649191,"visible":true,"origin":"","legend":"Reporting Summary","description":"","filename":"nrreportingsummaryNMEDA146514.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/273921e39cd4d2c5aff079a3.pdf"},{"id":94988802,"identity":"80670342-f1b3-46ac-97d4-0025e725a227","added_by":"auto","created_at":"2025-11-03 07:10:57","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":34523,"visible":true,"origin":"","legend":"CONSORT Checklist","description":"","filename":"CONSORT2025DHIM4NMEDA146514v1.0.docx","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/ece8f0068cb2f6c88966642c.docx"},{"id":94988083,"identity":"0ad07cf8-3589-44fe-ac28-289774b8d2a5","added_by":"auto","created_at":"2025-11-03 07:04:32","extension":"pdf","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":1024417,"visible":true,"origin":"","legend":"Statistical Analysis Plan","description":"","filename":"SAPDHIM4version12JUN2024.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/2631a9d35c47173dd295c51e.pdf"},{"id":94920071,"identity":"3e920786-fd7c-4adb-8635-9fe3c33f54f6","added_by":"auto","created_at":"2025-11-01 13:20:33","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":6594834,"visible":true,"origin":"","legend":"Supplemental Appendix","description":"","filename":"SupplementalAppendixDHIM4NMEDA146514v1.0Oct242025.docx","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/4f4631ee5a3bb46d67136a2a.docx"},{"id":94920072,"identity":"17207f8e-8a63-452c-bd21-7277cfc297c3","added_by":"auto","created_at":"2025-11-01 13:20:33","extension":"pdf","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":1535533,"visible":true,"origin":"","legend":"Study Protocol","description":"","filename":"Protocolv6.0DHIM4Homologous17April2023.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/a3069a7dc5ecf92058f85760.pdf"},{"id":94920070,"identity":"33f6794e-d9b0-474a-86b1-415098c05472","added_by":"auto","created_at":"2025-11-01 13:20:33","extension":"pdf","order_by":6,"title":"","display":"","copyAsset":false,"role":"supplement","size":1666970,"visible":true,"origin":"","legend":"Editorial Policy Checklist","description":"","filename":"nreditorialpolicychecklistNMEDA146514.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7947800/v1/d42c4476a923b211cd10a0b7.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"First-in-Human Dengue Serotype 4 Live Virus Human Challenge: A Phase 1 Dose Optimization and Homologous Rechallenge Study","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7947800/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7947800/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Dengue Live Virus Human Challenges (LVHC) are critically needed in dengue vaccine and pharmacologic development to down-select candidates and provides a useful platform for understanding viral-host immunology in a controlled setting. We conducted a first-in-human phase 1 open label study evaluating the safety and optimized dose of an underattenuated dengue virus serotype-4-LVHC (DENV-4-LVHC) strain H-241. The study was divided into a dose optimization study followed by a homologous rechallenge substudy. Fourteen healthy adult participants were enrolled and challenged with a subcutaneous dose of DENV-4-LVHC. All 14 developed viremia and symptoms consistent with self-limited, mild-moderate dengue. Six participants were rechallenged using the optimized dose 1 year after primary challenge, and none developed detectable dengue. Robust antibody responses, plasmablast expansion, and antiviral gene upregulation were seen during primary infection but not after rechallenge. No severe dengue, need for inpatient observation, or dengue challenge-related serious adverse events were observed. DENV-4-LVHC was found to be safe and highly predictable for use in future studies to evaluate vaccine and therapeutic candidates. Immunity from prior DENV-4-LVHC infection conferred protection following homologous rechallenge one year after primary exposure. 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