{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T19:14:31Z","timestamp":1791054871565,"version":"4.1.0"},"reference-count":27,"publisher":"National Academy of Sciences","issue":"48","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2009,12]]},"abstract":"<jats:p>\n                    A major concern about the ongoing swine-origin H1N1 influenza virus (S-OIV) outbreak is that the virus may be so different from seasonal H1N1 that little immune protection exists in the human population. In this study, we examined the molecular basis for pre-existing immunity against S-OIV, namely the recognition of viral immune epitopes by T cells or B cells\/antibodies that have been previously primed by circulating influenza strains. Using data from the Immune Epitope Database, we found that only 31% (8\/26) of B-cell epitopes present in recently circulating H1N1 strains are conserved in the S-OIV, with only 17% (1\/6) conserved in the hemagglutinin (HA) and neuraminidase (NA) surface proteins. In contrast, 69% (54\/78) of the epitopes recognized by CD8\n                    <jats:sup>+<\/jats:sup>\n                    T cells are completely invariant. We further demonstrate experimentally that some memory T-cell immunity against S-OIV is present in the adult population and that such memory is of similar magnitude as the pre-existing memory against seasonal H1N1 influenza. Because protection from infection is antibody mediated, a new vaccine based on the specific S-OIV HA and NA proteins is likely to be required to prevent infection. However, T cells are known to blunt disease severity. Therefore, the conservation of a large fraction of T-cell epitopes suggests that the severity of an S-OIV infection, as far as it is determined by susceptibility of the virus to immune attack, would not differ much from that of seasonal flu. These results are consistent with reports about disease incidence, severity, and mortality rates associated with human S-OIV.\n                  <\/jats:p>","DOI":"10.1073\/pnas.0911580106","type":"journal-article","created":{"date-parts":[[2009,11,16]],"date-time":"2009-11-16T22:24:45Z","timestamp":1258410285000},"page":"20365-20370","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":285,"title":["Pre-existing immunity against swine-origin H1N1 influenza viruses in the general human population"],"prefix":"10.1073","volume":"106","author":[{"given":"Jason A.","family":"Greenbaum","sequence":"first","affiliation":[{"name":"Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maya F.","family":"Kotturi","sequence":"additional","affiliation":[{"name":"Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yohan","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carla","family":"Oseroff","sequence":"additional","affiliation":[{"name":"Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kerrie","family":"Vaughan","sequence":"additional","affiliation":[{"name":"Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nima","family":"Salimi","sequence":"additional","affiliation":[{"name":"Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Randi","family":"Vita","sequence":"additional","affiliation":[{"name":"Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Julia","family":"Ponomarenko","sequence":"additional","affiliation":[{"name":"San Diego Supercomputer Center, University of California at San Diego, La Jolla, CA 92093; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Richard H.","family":"Scheuermann","sequence":"additional","affiliation":[{"name":"Department of Pathology and Division of Biomedical Informatics, University of Texas Southwestern Medical Center, Dallas, TX 75390"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alessandro","family":"Sette","sequence":"additional","affiliation":[{"name":"Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bjoern","family":"Peters","sequence":"additional","affiliation":[{"name":"Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2009,12]]},"reference":[{"key":"e_1_3_3_1_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.324_1496"},{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.1176225"},{"key":"e_1_3_3_3_2","doi-asserted-by":"publisher","DOI":"10.1038\/nature08260"},{"key":"e_1_3_3_4_2","first-page":"521","article-title":"Serum cross-reactive antibody response to a novel influenza A (H1N1) virus after vaccination with seasonal influenza vaccine","volume":"58","year":"2009","unstructured":", Serum cross-reactive antibody response to a novel influenza A (H1N1) virus after vaccination with seasonal influenza vaccine. MMWR 58, 521\u2013524 (2009).","journal-title":"MMWR"},{"key":"e_1_3_3_5_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.1177127"},{"key":"e_1_3_3_6_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.1177238"},{"key":"e_1_3_3_7_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0609330104"},{"key":"e_1_3_3_8_2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pbio.0030091"},{"key":"e_1_3_3_9_2","doi-asserted-by":"publisher","DOI":"10.1128\/JVI.02005-07"},{"key":"e_1_3_3_10_2","doi-asserted-by":"publisher","DOI":"10.1038\/442981a"},{"key":"e_1_3_3_11_2","doi-asserted-by":"publisher","DOI":"10.1128\/JVI.00751-07"},{"key":"e_1_3_3_12_2","first-page":"25","article-title":"An overview of serum antibody responses to influenza virus antigens","volume":"115","author":"Couch RB","year":"2003","unstructured":"RB Couch, An overview of serum antibody responses to influenza virus antigens. Dev Biol (Basel) 115, 25\u201330 (2003).","journal-title":"Dev Biol (Basel)"},{"key":"e_1_3_3_13_2","doi-asserted-by":"publisher","DOI":"10.1128\/JVI.02165-08"},{"key":"e_1_3_3_14_2","doi-asserted-by":"publisher","DOI":"10.1002\/eji.1830140414"},{"key":"e_1_3_3_15_2","doi-asserted-by":"publisher","DOI":"10.1128\/JVI.01047-08"},{"key":"e_1_3_3_16_2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJM198307073090103"},{"key":"e_1_3_3_17_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1232449100"},{"key":"e_1_3_3_18_2","doi-asserted-by":"publisher","DOI":"10.4049\/jimmunol.176.10.6333"},{"key":"e_1_3_3_19_2","doi-asserted-by":"publisher","DOI":"10.1084\/jem.175.4.1143"},{"key":"e_1_3_3_20_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.031575198"},{"key":"e_1_3_3_21_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.1124513"},{"key":"e_1_3_3_22_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0811052106"},{"key":"e_1_3_3_23_2","doi-asserted-by":"publisher","DOI":"10.1006\/viro.1998.9508"},{"key":"e_1_3_3_24_2","doi-asserted-by":"publisher","DOI":"10.1128\/JVI.02694-07"},{"key":"e_1_3_3_25_2","first-page":"3478","article-title":"Memory T cells established by seasonal human influenza A infection cross-react with avian influenza A (H5N1) in healthy individuals","volume":"118","author":"Lee LY","year":"2008","unstructured":"LY Lee, et al., Memory T cells established by seasonal human influenza A infection cross-react with avian influenza A (H5N1) in healthy individuals. J Clin Invest 118, 3478\u20133490 (2008).","journal-title":"J Clin Invest"},{"key":"e_1_3_3_26_2","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/gkg520"},{"key":"e_1_3_3_27_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0506768102"}],"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.0911580106","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,12]],"date-time":"2022-04-12T19:06:42Z","timestamp":1649790402000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.0911580106"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2009,12]]},"references-count":27,"journal-issue":{"issue":"48","published-print":{"date-parts":[[2009,12]]}},"alternative-id":["10.1073\/pnas.0911580106"],"URL":"https:\/\/doi.org\/10.1073\/pnas.0911580106","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[2009,12]]},"assertion":[{"value":"2009-08-31","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2009-12-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}