Influenza PA Substitutions and Genetic Diversity of A(H1N1)pdm09, A(H3N2), and B/Victoria Viruses in Japan During the 2023–2024 Season
Rattachement africain : jp, gb. Niveau de preuve : code pays fourni par la source.
Le résumé fourni par la source
We characterized influenza A(H1N1)pdm09, A(H3N2), and B/Victoria viruses circulating in Japan during 2023-2024, focusing on lineage placement relative to WHO-recommended vaccine strains and on baloxavir resistance (PA/I38T substitutions). We enrolled 210 outpatients with influenza-like illness across eight clinics in six prefectures (October 2023-September 2024). Of these, 209 had an analyzable pre-treatment respiratory specimen for RT-PCR; hemagglutinin (HA) and neuraminidase (NA) genes were sequenced by next-generation sequencing (NGS). PA/I38T substitutions that confer baloxavir resistance were assessed by cycling-probe RT-PCR, Sanger sequencing, and NGS. HA phylogenies were constructed with global datasets and WHO vaccine reference strains. Of 209 pre-treatment specimens, 181 were influenza-positive (A(H1N1)pdm09 44.2%, A(H3N2) 37.6%, B/Victoria 18.2%); 51 follow-up specimens were collected ≈4-5 days after baloxavir or neuraminidase inhibitor therapy. HA phylogeny placed A(H1N1)pdm09 in clades 5a.2a/5a.2a.1 with predominance of subclade D.2. A(H3N2) clustered exclusively in clade 2a.3a.1 (J lineage, mostly J.1), indicating a mismatch with the season's A/Darwin/9/2021 vaccine component and supporting the subsequent J-lineage update. All B/Victoria genomes fell within V1A.3a.2 on a C.5 backbone (C.5.1 and C.5.7). No PA/I38T variant was detected in any pre-treatment specimen. Post-baloxavir, PA/I38T emerged in one A(H3N2) case (confirmed by all three methods) and in one B/Victoria case detected by NGS only (minority variant in a low-load sample). NA genes showed no substitutions associated with reduced susceptibility to laninamivir (e.g., E119A, G147E). During 2023-2024, A(H1N1)pdm09 and B/Victoria remained genetically aligned with their vaccine components, whereas A(H3N2) shifted to the J lineage, consistent with the 2024-2025 vaccine update. Although pre-treatment PA/I38T was absent, low-frequency on-therapy selection was observed, including a rare PA/I38T in influenza B/Victoria detected by NGS, suggesting the value of deep sequencing when viral loads are low. These integrated genomic-clinical data support vaccine strain realignment for H3N2 and continued monitoring of baloxavir resistance in outpatient care.
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Le contrôle bibliographique ouvert
DOI retrouvé dans Crossref DOI retrouvé ; titre concordant.
- Titre Crossref
- Influenza PA Substitutions and Genetic Diversity of A(H1N1)pdm09, A(H3N2), and B/Victoria Viruses in Japan During the 2023–2024 Season
- Date Crossref
- 21/12/2025
- Éditeur
- MDPI AG
- Type
- journal-article
Ce recoupement confirme des métadonnées liées au DOI. Il ne confirme ni la méthode ni les conclusions de l’étude, et il ne compte pas comme une seconde source scientifique indépendante.
Où se fait cette recherche
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Niigata University Institute for Research Administration pays non établi dans la noticeUniversité ou école supérieure
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University of Leicester Department of Respiratory Sciences pays non établi dans la noticeUniversité ou école supérieure
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University Hospitals of Leicester NHS Trust Department of Clinical Microbiology pays non établi dans la noticeÉtablissement de santé
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Suzuki (Japan) pays non établi dans la noticeEntreprise
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Graduate School of Medical and Dental Sciences Division of International Health (Public Health) pays non établi dans la noticeUniversité ou école supérieure
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Furano Kyokai Hospital pays non établi dans la noticeÉtablissement de santé
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Kawashima Medical Clinic pays non établi dans la noticeÉtablissement de santé
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Yoiko Pediatric Clinic pays non établi dans la noticeÉtablissement de santé
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Kodo Pediatrics pays non établi dans la noticeInstitution
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Suzuki Pediatric Clinic pays non établi dans la noticeÉtablissement de santé
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Masaki Respiratory Medicine Clinic pays non établi dans la noticeÉtablissement de santé
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Juzenkai Hospital pays non établi dans la noticeÉtablissement de santé
Institute for Research Administration — Niigata University, Department of Respiratory Sciences — University of Leicester et Department of Clinical Microbiology — University Hospitals of Leicester NHS Trust, avec 9 autres affiliations.
Une affiliation ne permet pas de déduire la nationalité d’un auteur.