[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]
Transbound Emerg Dis. 2019 Jul 11. doi: 10.1111/tbed.13291. [Epub ahead of print]
A novel H7N3 reassortant originating from the zoonotic H7N9 highly pathogenic avian influenza viruses that has adapted to ducks.
Nakayama M1, Uchida Y1, Shibata A2, Kobayashi Y3, Mine J1, Takemae N1, Tsunekuni R1, Tanikawa T1, Harada R2, Osaka H2, Saito T1,4.
Author information: 1 Division of Transboundary Animal Disease, National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan. 2 Exotic Disease Inspection Division, Laboratory Department, Animal Quarantine Service, Ministry of Agriculture, Forestry and Fisheries, Tokoname, Aichi, 479-0881, Japan. 3 Pathological and Physiochemical Examination Division, Laboratory Department, Animal Quarantine Service, Ministry of Agriculture, Forestry and Fisheries, Yokohama, Kanagawa, 235-0008, Japan. 4 United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
The first human case of zoonotic H7N9 avian influenza virus (AIV) infection was reported in March 2013 in China. This virus continues to circulate in poultry in China while mutating to highly pathogenic AIVs (HPAIVs). Through monitoring at airports in Japan, a novel H7N3 reassortant of the zoonotic H7N9 HPAIVs, A/duck/Japan/AQ-HE30-1/2018 (HE30-1), was detected in a poultry meat product illegally brought by a passenger from China into Japan. We analyzed the genetic, pathogenic, and antigenic characteristics of HE30-1 by comparing it with previous zoonotic H7N9 AIVs and their reassortants. Phylogenetic analysis of the entire HE30-1 genomic sequence revealed that it comprised at least three different sources; the HA (H7), PB1, PA, NP, M, and NS segments of HE30-1 were directly derived from H7N9 AIVs, whereas the NA (N3) and PB2 segments of HE30-1 were unrelated to zoonotic H7N9. Experimental infection revealed that HE30-1 was lethal in chickens but not in domestic or mallard ducks. HE30-1 was shed from and replicated in domestic and mallard ducks and chickens, whereas previous zoonotic H7N9 AIVs have not adapted well to ducks. This finding suggests the possibility that HE30-1 may disseminate to remote area by wild bird migration once it establishes in wild bird population. A hemagglutination-inhibition assay indicated that antigenic drift has occurred among the reassortants of zoonotic H7N9 AIVs; HE30-1 showed similar antigenicity to some of those H7N9 AIVs, suggesting it might be prevented by the H5/H7 inactivated vaccine that was introduced in China in 2017. Our study reports the emergence of a new reassortant of zoonotic H7N9 AIVs with novel viral characteristics and warns of the challenge we still face to control the zoonotic H7N9 AIVs and their reassortants.
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KEYWORDS: adaptation to ducks; animal experiments; novel H7N3 reassortant; zoonotic H7N9 avian influenza viruses
PMID: 31293102 DOI: 10.1111/tbed.13291
Keywords: Avian Influenza; H7N3; H7N9; Reassortant strain; Animal models.