{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T16:11:59Z","timestamp":1784736719217,"version":"3.55.0"},"reference-count":91,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2020,12,26]],"date-time":"2020-12-26T00:00:00Z","timestamp":1608940800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["2018M3A9H4055193"],"award-info":[{"award-number":["2018M3A9H4055193"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["2015R1A6A1A03032236"],"award-info":[{"award-number":["2015R1A6A1A03032236"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>Influenza A virus subtype H1N1 has caused global pandemics like the \u201cSpanish flu\u201d in 1918 and the 2009 H1N1 pandemic several times. H1N1 remains in circulation and survives in multiple animal sources, including wild birds. Surveillance during the winter of 2018\u20132019 in Korea revealed two H1N1 isolates in samples collected from wild bird feces: KNU18-64 (A\/Greater white-fronted goose\/South Korea\/KNU18-64\/2018(H1N1)) and WKU19-4 (A\/wild bird\/South Korea\/WKU19-4\/2019(H1N1)). Phylogenetic analysis indicated that M gene of KNU18-64(H1N1) isolate resembles that of the Alaskan avian influenza virus, whereas WKU19-4(H1N1) appears to be closer to the Mongolian virus. Molecular characterization revealed that they harbor the amino acid sequence PSIQRS\u2193GLF and are low-pathogenicity influenza viruses. In particular, the two isolates harbored three different mutation sites, indicating that they have different virulence characteristics. The mutations in the PB1-F2 and PA protein of WKU19-4(H1N1) indicate increasing polymerase activity. These results corroborate the kinetic growth data for WKU19-4 in MDCK cells: a dramatic increase in the viral titer after 12 h post-inoculation compared with that in the control group H1N1 (CA\/04\/09(pdm09)). The KNU18-64(H1N1) isolate carries mutations indicating an increase in mammal adaptation; this characterization was confirmed by the animal study in mice. The KNU18-64(H1N1) group showed the presence of viruses in the lungs at days 3 and 6 post-infection, with titers of 2.71 \u00b1 0.16 and 3.71 \u00b1 0.25 log10(TCID50\/mL), respectively, whereas the virus was only detected in the WKU19-4(H1N1) group at day 6 post-infection, with a lower titer of 2.75 \u00b1 0.51 log10(TCID50\/mL). The present study supports the theory that there is a relationship between Korea and America with regard to reassortment to produce novel viral strains. Therefore, there is a need for increased surveillance of influenza virus circulation in free-flying and wild land-based birds in Korea, particularly with regard to Alaskan and Asian strains.<\/jats:p>","DOI":"10.3390\/v13010030","type":"journal-article","created":{"date-parts":[[2020,12,27]],"date-time":"2020-12-27T20:52:21Z","timestamp":1609102341000},"page":"30","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Emergence of Novel Reassortant H1N1 Avian Influenza Viruses in Korean Wild Ducks in 2018 and 2019"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4541-8198","authenticated-orcid":false,"given":"Thuy-Tien Thi","family":"Trinh","sequence":"first","affiliation":[{"name":"Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bao Tuan","family":"Duong","sequence":"additional","affiliation":[{"name":"Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anh Thi Viet","family":"Nguyen","sequence":"additional","affiliation":[{"name":"Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hien Thi","family":"Tuong","sequence":"additional","affiliation":[{"name":"Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vui Thi","family":"Hoang","sequence":"additional","affiliation":[{"name":"Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Duong Duc","family":"Than","sequence":"additional","affiliation":[{"name":"Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"SunJeong","family":"Nam","sequence":"additional","affiliation":[{"name":"Division of EcoScience, Ewha University, Seoul 03760, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7715-1390","authenticated-orcid":false,"given":"Haan Woo","family":"Sung","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Kangwon National University, Chuncheon 200-701, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ki-Jung","family":"Yun","sequence":"additional","affiliation":[{"name":"Department of Pathology, School of Medicine, Wonkwang University, Iksan 570-749, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Seon-Ju","family":"Yeo","sequence":"additional","affiliation":[{"name":"Department of Tropical Medicine and Parasitology, College of Medicine, Seoul National University, Seoul 03080, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyun","family":"Park","sequence":"additional","affiliation":[{"name":"Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,12,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"5637","DOI":"10.1016\/j.vaccine.2006.10.051","article-title":"An overview of the epidemiology of avian influenza","volume":"25","author":"Alexander","year":"2007","journal-title":"Vaccine"},{"key":"ref_2","unstructured":"CDC (2017, April 19). 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