{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T17:08:47Z","timestamp":1785431327412,"version":"3.56.0"},"reference-count":50,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,4,11]],"date-time":"2026-04-11T00:00:00Z","timestamp":1775865600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001665","name":"Agence Nationale de la Recherche","doi-asserted-by":"publisher","award":["ANR-18-CE18-0028"],"award-info":[{"award-number":["ANR-18-CE18-0028"]}],"id":[{"id":"10.13039\/501100001665","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001665","name":"Agence Nationale de la Recherche","doi-asserted-by":"publisher","award":["ANR-10-LABX-62-IBEID"],"award-info":[{"award-number":["ANR-10-LABX-62-IBEID"]}],"id":[{"id":"10.13039\/501100001665","id-type":"DOI","asserted-by":"publisher"}]},{"award":["ANR-18-CE18-0028"],"award-info":[{"award-number":["ANR-18-CE18-0028"]}],"id":[{"id":"https:\/\/ror.org\/00rbzpz17","id-type":"ROR","asserted-by":"publisher"}]},{"award":["ANR-10-LABX-62-IBEID"],"award-info":[{"award-number":["ANR-10-LABX-62-IBEID"]}],"id":[{"id":"https:\/\/ror.org\/00rbzpz17","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Federal Ministry of Technology, Research and Space","award":["01KI2508A"],"award-info":[{"award-number":["01KI2508A"]}]},{"award":["01KI2508A"],"award-info":[{"award-number":["01KI2508A"]}],"id":[{"id":"https:\/\/ror.org\/04pz7b180","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>Understanding the genetic changes that allow avian influenza A viruses (IAVs) to switch their natural hosts and establish productive infection in humans is important for pandemic risk assessment. Adaptations in the IAV polymerase are required to overcome species-specific restrictions imposed by host ANP32 proteins. Notably, avian virus polymerase is generally only poorly supported by human ANP32 proteins due to species-specific differences. Consequently, efficient polymerase adaptation to the binding interface of human ANP32 requires distinct amino acid changes, such as PB2 E627K. A separate adaptation, PB2 M631L, has recently been reported in mammalian-adapted IAV; however, its functional role across divergent viral lineages and its relationship to host ANP32-dependent adaptation remain incompletely defined. Here, we examine PB2 M631L in the polymerases of a 1918 pandemic strain, a recombinant contemporary H1N1pdm09, and a recent clade 2.3.4.4b H5N1 virus. Using polymerase activity and protein-interaction assays, we show that PB2 M631L enhances polymerase activity and ANP32 binding in human\u2014but not avian\u2014contexts, and that this effect is conserved across multiple viral backgrounds. In H1N1pdm09, PB2 M631L also increased virus replication in mammalian cells. These findings indicate that PB2 M631L contributes to enhanced polymerase compatibility with human ANP32 proteins and are consistent with a role in adaptation across multiple influenza virus lineages. Our results highlight how analysis of historical pandemic strains can inform risk assessment for future emerging viruses.<\/jats:p>","DOI":"10.3390\/microorganisms14040859","type":"journal-article","created":{"date-parts":[[2026,4,13]],"date-time":"2026-04-13T11:38:26Z","timestamp":1776080306000},"page":"859","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Historical Pandemic and Contemporary Influenza A Viruses Reveal PB2 M631L as a Convergent Adaptation to Human ANP32"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5960-515X","authenticated-orcid":false,"given":"Matthias","family":"Budt","sequence":"first","affiliation":[{"name":"Unit 17 Influenza and other Respiratory Viruses, Robert Koch Institute, 13353 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Irina","family":"Barac","sequence":"additional","affiliation":[{"name":"Unit 17 Influenza and other Respiratory Viruses, Robert Koch Institute, 13353 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jessica","family":"Kohs","sequence":"additional","affiliation":[{"name":"Unit 17 Influenza and other Respiratory Viruses, Robert Koch Institute, 13353 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tim","family":"Krischuns","sequence":"additional","affiliation":[{"name":"Institut Pasteur, Universit\u00e9 Paris Cit\u00e9, CNRS UMR 3569, RNA Biology of Influenza Virus, 75015 Paris, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0424-0277","authenticated-orcid":false,"given":"Nadia","family":"Naffakh","sequence":"additional","affiliation":[{"name":"Institut Pasteur, Universit\u00e9 Paris Cit\u00e9, CNRS UMR 3569, RNA Biology of Influenza Virus, 75015 Paris, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7688-236X","authenticated-orcid":false,"given":"Thorsten","family":"Wolff","sequence":"additional","affiliation":[{"name":"Unit 17 Influenza and other Respiratory Viruses, Robert Koch Institute, 13353 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1122","DOI":"10.1038\/nature08182","article-title":"Origins and evolutionary genomics of the 2009 swine-origin H1N1 influenza A epidemic","volume":"459","author":"Smith","year":"2009","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"440","DOI":"10.1016\/j.chom.2010.05.009","article-title":"Influenza virus evolution, host adaptation, and pandemic formation","volume":"7","author":"Taubenberger","year":"2010","journal-title":"Cell Host Microbe"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1353\/bhm.2002.0022","article-title":"Updating the accounts: Global mortality of the 1918\u20131920 \u201cSpanish\u201d influenza pandemic","volume":"76","author":"Johnson","year":"2002","journal-title":"Bull. 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