{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T02:48:43Z","timestamp":1791946123154,"version":"4.3.4"},"reference-count":30,"publisher":"European Respiratory Society (ERS)","issue":"5","license":[{"start":{"date-parts":[[2025,2,27]],"date-time":"2025-02-27T00:00:00Z","timestamp":1740614400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100010767","name":"Innovative Medicines Initiative","doi-asserted-by":"publisher","award":["101034339."],"award-info":[{"award-number":["101034339."]}],"id":[{"id":"10.13039\/501100010767","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["publications.ersnet.org"],"crossmark-restriction":true},"short-container-title":["ERJ Open Res"],"accepted":{"date-parts":[[2025,2,9]]},"published-print":{"date-parts":[[2025,9]]},"abstract":"<jats:sec>\n                  <jats:title>Aims<\/jats:title>\n                  <jats:p>Past research suggested respiratory syncytial virus (RSV) specific serum immunoglobulin A (IgA) antibodies as a biomarker of previous RSV infections in young infants accounting for maternal immunity. This study aimed to confirm this association and to establish a serological threshold for discriminating RSV-na\u00efve infants from those who have experienced RSV.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Material and methods<\/jats:title>\n                  <jats:p>This study involves 135 infants from the LoewenKIDS study with nasal swabs collected at each acute respiratory infection, and serum samples collected at ages 1 and 2\u2005years. RSV presence in swabs was ascertained by reverse transcriptase PCR; RSV-specific IgG and IgA antibody levels against five different structural proteins and RSV neutralising antibodies were measured in sera. Robust Mixture Discriminant Analysis was used to determine the cut-off values and account for false negatives.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>Of 135 included infants, 131 had available data at year 1 (Y1) and 95 at year 2 (Y2). Pre-F IgA concentrations were higher in infants with PCR-confirmed RSV infections. There was a further increase in IgA, IgG and neutralising antibody titre concentrations from Y1 to Y2 consistent with re-infections. Based on robust mixture discriminant analysis, the cut-off values of pre-F IgA level indicative of past RSV infection were 0.23\u2005AU\u00b7mL<jats:sup>\u22121<\/jats:sup> at Y1 and 0.22\u2005AU\u00b7mL<jats:sup>\u22121<\/jats:sup> at Y2.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusion<\/jats:title>\n                  <jats:p>This study shows that in children aged &lt;2\u2005years, a previous RSV infection is accompanied by serum pre-F IgA antibody levels above 0.22\u2005AU\u00b7mL<jats:sup>\u22121<\/jats:sup>, a value close to a previously proposed cut-off (0.19\u2005AU\u00b7mL<jats:sup>\u22121<\/jats:sup>) based on seroresponse data only. The confirmed threshold can be of use in studies assessing vaccination strategies.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1183\/23120541.01288-2024","type":"journal-article","created":{"date-parts":[[2025,3,7]],"date-time":"2025-03-07T07:09:57Z","timestamp":1741331397000},"page":"01288-2024","update-policy":"https:\/\/doi.org\/10.1183\/ers-crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["Serum immunoglobulin A as a biomarker for respiratory syncytial virus infection in children aged &lt;2\u2005years"],"prefix":"10.1183","volume":"11","author":[{"given":"Annick","family":"Moureau","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rafael","family":"Mikolajczyk","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cornelia","family":"Gottschick","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bianca","family":"Klee","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rob","family":"van Binnendijk","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rutger","family":"Schepp","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3052-2793","authenticated-orcid":false,"given":"Ryan S.","family":"Thwaites","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Donghui","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yichen","family":"Jia","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-9915-3232","authenticated-orcid":false,"given":"Charlotte","family":"Vernhes","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"name":"for the PROMISE investigators","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"81","published-online":{"date-parts":[[2025,2,27]]},"reference":[{"key":"2025092202451785000_11.5.01288-2024.1","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(17)30938-8"},{"key":"2025092202451785000_11.5.01288-2024.2","doi-asserted-by":"publisher","DOI":"10.1093\/infdis\/jiy056"},{"key":"2025092202451785000_11.5.01288-2024.3","doi-asserted-by":"publisher","DOI":"10.1016\/s0140-6736(22)00478-0"},{"key":"2025092202451785000_11.5.01288-2024.4","doi-asserted-by":"publisher","DOI":"10.1016\/j.prrv.2015.05.005"},{"key":"2025092202451785000_11.5.01288-2024.5","doi-asserted-by":"publisher","DOI":"10.1542\/peds.2019-3611"},{"key":"2025092202451785000_11.5.01288-2024.6","doi-asserted-by":"crossref","first-page":"501","DOI":"10.1007\/s11262-022-01932-6","article-title":"Impact of genetic polymorphisms related to innate immune response on respiratory syncytial virus infection in children","volume":"58","author":"C\u00f3rdova-D\u00e1valos","year":"2022","journal-title":"Virus Genes"},{"key":"2025092202451785000_11.5.01288-2024.7","doi-asserted-by":"crossref","first-page":"1669","DOI":"10.1016\/S0140-6736(23)00811-5","article-title":"Respiratory syncytial virus infection during infancy and asthma during childhood in the USA (INSPIRE): a population-based, prospective birth cohort study","volume":"401","author":"Rosas-Salazar","year":"2023","journal-title":"The Lancet"},{"key":"2025092202451785000_11.5.01288-2024.8","doi-asserted-by":"crossref","first-page":"4073","DOI":"10.7150\/ijbs.64762","article-title":"Respiratory syncytial virus: from pathogenesis to potential therapeutic strategies","volume":"17","author":"Shang","year":"2021","journal-title":"Int J Biol Sci"},{"key":"2025092202451785000_11.5.01288-2024.9","doi-asserted-by":"publisher","DOI":"10.1126\/science.1234914"},{"key":"2025092202451785000_11.5.01288-2024.10","doi-asserted-by":"publisher","DOI":"10.1007\/s40265-022-01829-6"},{"key":"2025092202451785000_11.5.01288-2024.11","unstructured":"European Medicines Agency . 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