{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T10:38:16Z","timestamp":1766486296917,"version":"build-2065373602"},"reference-count":74,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2025,6,7]],"date-time":"2025-06-07T00:00:00Z","timestamp":1749254400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Korea Health Technology R&amp;D Project through the Korea Health Industry Development Institute (KHIDI)","award":["RS-2022-KH128619","RS-2024-00399869"],"award-info":[{"award-number":["RS-2022-KH128619","RS-2024-00399869"]}]},{"name":"Ministry of Health &amp; Welfare, Republic of Korea","award":["RS-2022-KH128619","RS-2024-00399869"],"award-info":[{"award-number":["RS-2022-KH128619","RS-2024-00399869"]}]},{"DOI":"10.13039\/501100003668","name":"Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry (IPET)","doi-asserted-by":"publisher","award":["RS-2022-KH128619","RS-2024-00399869"],"award-info":[{"award-number":["RS-2022-KH128619","RS-2024-00399869"]}],"id":[{"id":"10.13039\/501100003668","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Ministry of Agriculture, Food and Rural Affairs (MAFRA)","award":["RS-2022-KH128619","RS-2024-00399869"],"award-info":[{"award-number":["RS-2022-KH128619","RS-2024-00399869"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>During the 2009 H1N1 pandemic (pdm09), the poor replication of PR8-derived vaccine strains in embryonated chicken eggs (ECEs) delayed vaccine production, necessitating costly adjuvants. To improve egg-based yield, we generated PB2-substituted H1N1 strains via reverse genetics, replacing PR8 PB2 with a PB2 lacking mammalian-adaptive mutations (dtxPB2), cognate pdm09 PB2 (19PB2), or avian PB2. All PB2-substituted strains achieved over tenfold higher titers than the conventional PR8 PB2-containing strain (rGD19), with rGD19\/dtxPB2 and rGD19\/19PB2 exhibiting significantly higher titers and reduced murine virulence. Among these, rGD19\/19PB2 produced the highest hemagglutinin (HA) yield and, when administered intranasally as a binary ethyleneimine (BEI)-inactivated whole-virion vaccine, elicited a significantly stronger broncho-alveolar IgA response than rGD19. Both rGD19 and rGD19\/19PB2 provided comparable protection against a homologous H1N1 challenge, yet only rGD19\/19PB2 conferred full survival protection after a lethal heterologous H3N2 challenge. These findings show that incorporation of cognate PB2 enhances H1N1 replication in ECEs and antigen yield, reduces murine virulence, and confers robust homo- and heterosubtypic protection via intranasal immunization, underscoring the promise of PB2-modified H1N1 strains as inactivated mucosal whole-virion vaccines for future vaccine development.<\/jats:p>","DOI":"10.3390\/ijms26125489","type":"journal-article","created":{"date-parts":[[2025,6,9]],"date-time":"2025-06-09T06:46:01Z","timestamp":1749451561000},"page":"5489","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A High-Yield Recombinant Inactivated Whole-Virion Nasal Influenza A(H1N1)pdm09 Virus Vaccine with an Attenuated PB2 Gene"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4558-8990","authenticated-orcid":false,"given":"Seung-Eun","family":"Son","sequence":"first","affiliation":[{"name":"Laboratory of Avian Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jin-Ha","family":"Song","sequence":"additional","affiliation":[{"name":"Laboratory of Avian Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5509-1152","authenticated-orcid":false,"given":"Ho-Won","family":"Kim","sequence":"additional","affiliation":[{"name":"Laboratory of Avian Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2206-1299","authenticated-orcid":false,"given":"Se-Hee","family":"An","sequence":"additional","affiliation":[{"name":"Avian Influenza Research & Diagnostic Division, Animal and Plant Quarantine Agency, Gimcheon-si 39660, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Seung-Ji","family":"Kim","sequence":"additional","affiliation":[{"name":"Laboratory of Avian Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3037-7581","authenticated-orcid":false,"given":"Chung-Young","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Microbiology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9107-7860","authenticated-orcid":false,"given":"Hyuk-Joon","family":"Kwon","sequence":"additional","affiliation":[{"name":"Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea"},{"name":"Laboratory of Poultry Medicine, Department of Farm Animal Medicine, College of Veterinary Medicine and BK21 PLUS for Veterinary Science, Seoul National University, Seoul 88026, Republic of Korea"},{"name":"Farm Animal Clinical Training and Research Center (FACTRC), Institutes of Green Bio Science and Technology (GBST), Seoul National University, Pyeongchang 25354, Republic of Korea"},{"name":"GeNiner Inc., Seoul 08826, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6825-6924","authenticated-orcid":false,"given":"Kang-Seuk","family":"Choi","sequence":"additional","affiliation":[{"name":"Laboratory of Avian Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea"},{"name":"Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1196\/annals.1408.001","article-title":"Biology of influenza a virus","volume":"1102","author":"Cheung","year":"2007","journal-title":"Ann. 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