Genetic characterization and pathogenicity assessment of highly pathogenic H5N1 avian influenza viruses isolated from migratory wild birds in 2011, South Korea

• Published in: Virus research Vol. 160; no. 1-2; pp. 305 - 315
• Main Authors: Kwon, Hyeok-il, Song, Min-Suk, Pascua, Philippe Noriel Q., Baek, Yun Hee, Lee, Jun Han, Hong, Seung-Pyo, Rho, Jong-Bok, Kim, Jeong-Ki, Poo, Haryoung, Kim, Chul-Joong, Choi, Young Ki
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.09.2011
• Subjects: Amino Acid Motifs; Animal models; Animals; Animals, Wild; Aves; avian influenza; Birds; Chickens; Cluster Analysis; Data processing; Domestic poultry outbreaks; Ducks; Experimental infection; feces; Feces - virology; Ferrets; Fowl plague; genes; Hemagglutinin Glycoproteins, Influenza Virus - genetics; hosts; HPAI H5N1 virus; humans; Influenza; Influenza A virus; Influenza A Virus, H5N1 Subtype - classification; Influenza A Virus, H5N1 Subtype - genetics; Influenza A Virus, H5N1 Subtype - isolation & purification; Influenza A Virus, H5N1 Subtype - pathogenicity; Influenza in Birds - virology; Mice; Mice, Inbred BALB C; migratory behavior; Molecular Sequence Data; monitoring; Mustela; pandemic; pandemics; Pathogenicity; Phylogeny; Poultry; Poultry Diseases - pathology; Poultry Diseases - virology; Public health; Recruitment; Republic of Korea; respiratory system; Respiratory System - virology; Respiratory tract; RNA, Viral - genetics; Rodent Diseases - pathology; Rodent Diseases - virology; Sequence Analysis, DNA; sequence homology; Virulence; viruses; Wild birds; Republic of Korea; Pathogenicity; Domestic poultry outbreaks; Wild birds; Ferrets; HPAI H5N1 virus
• ISSN: 0168-1702; 1872-7492
• DOI: 10.1016/j.virusres.2011.07.003

► Continued spread of HPAI H5N1 viruses pose potential threat to public health. ► We report isolation of HPAI H5N1 viruses (A/Md/Korea/W401/11 and A/Md/Korea/W404/11) from migratory birds. ► Viruses are genetically identical (99.8% sequence identity) showing high sequence similarities to Japanese and Mongolian-like isolates rather than previous Korean H5N1 viruses. ► Animal studies indicate high-pathogenicity in chickens and mice but not ducks and ferrets. ► Study underscores importance of continued surveillance of influenza viruses among migratory bird species for effective monitoring of high-pathogenicity or pandemic influenza viruses. The continued spread of a highly pathogenic avian influenza (HPAI) H5N1 virus among wild birds and poultry has posed a potential threat to human public health. In the present study, we report the isolation of HPAI H5N1 viruses (A/Md/Korea/W401/11 and A/Md/Korea/W404/11) from fecal samples of migratory birds. Genetic and phlyogenetic analyses demonstrated that these viruses are genetically identical possessing gene segments from avian virus origin and showing highest sequence similarities (as high as 99.8%) to A/Ws/Hokkaido/4/11 and 2009–2010 Mongolian-like clade 2.3.2 isolates rather than previous Korean H5N1 viruses. Both viruses possess the polybasic motif (QRERRRK/R) in HA but other genes did not bear additional virulence markers. Pathogenicity of A/Md/Korea/W401/11 was assessed and compared with a 2006 clade 2.2 HPAI H5N1 migratory bird isolate (A/EM/Korea/W149/06) in chickens, ducks, mice and ferrets. Experimental infection in these hosts showed that both viruses have high pathogenic potential in chickens (2.3–3.0LD50s) and mice (3.3–3.9LD50s), but A/Md/Korea/W401/11 was less pathogenic in duck and ferret models. Despite recovery of both infection viruses in the upper respiratory tract, efficient ferret-to-ferret transmission was not observed. These data suggest that the 2011 Korean HPAI wild bird H5N1 virus could replicate in mammalian hosts without pre-adaptation but could not sustain subsequent infection. This study highlights the role of migratory birds in the perpetuation and spread of HPAI H5N1 viruses in Far-East Asia. With the changing pathobiology caused by H5N1 viruses among wild and poultry birds, continued surveillance of influenza viruses among migratory bird species remains crucial for effective monitoring of high-pathogenicity or pandemic influenza viruses.