title: Reassortant swine influenza viruses isolated in Japan contain genes from pandemic A(H1N1) 2009.
abstract: In 2013, three reassortant swine influenza viruses (SIVs)-two H1N2 and one H3N2-were isolated from symptomatic pigs in Japan; each contained genes from the pandemic A(H1N1) 2009 virus and endemic SIVs. Phylogenetic analysis revealed that the two H1N2 viruses, A/swine/Gunma/1/2013 and A/swine/Ibaraki/1/2013, were reassortants that contain genes from the following three distinct lineages: (i) H1 and nucleoprotein (NP) genes derived from a classical swine H1 HA lineage uniquely circulating among Japanese SIVs; (ii) neuraminidase (NA) genes from human-like H1N2 swine viruses; and (iii) other genes from pandemic A(H1N1) 2009 viruses. The H3N2 virus, A/swine/Miyazaki/2/2013, comprised genes from two sources: (i) hemagglutinin (HA) and NA genes derived from human and human-like H3N2 swine viruses and (ii) other genes from pandemic A(H1N1) 2009 viruses. Phylogenetic analysis also indicated that each of the reassortants may have arisen independently in Japanese pigs. A/swine/Miyazaki/2/2013 were found to have strong antigenic reactivities with antisera generated for some seasonal human-lineage viruses isolated during or before 2003, whereas A/swine/Miyazaki/2/2013 reactivities with antisera against viruses isolated after 2004 were clearly weaker. In addition, antisera against some strains of seasonal human-lineage H1 viruses did not react with either A/swine/Gunma/1/2013 or A/swine/Ibaraki/1/2013. These findings indicate that emergence and spread of these reassortant SIVs is a potential public health risk.
authors.affiliation: Influenza and Prion Disease Research Center, National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan.
authors.forename: Katsushi
authors.initials: K
authors.lastname: Kanehira
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Takemae
authors.forename: Yuko
authors.initials: Y
authors.lastname: Uchida
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Hikono
authors.forename: Takehiko
authors.initials: T
authors.lastname: Saito
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D016000:Cluster Analysis; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics*; D057221:Influenza A Virus, H1N2 Subtype / Q000235:genetics / Q000302:isolation & purification*; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics / Q000302:isolation & purification*; D007564:Japan; D008969:Molecular Sequence Data; D009975:Orthomyxoviridae; D009976:Orthomyxoviridae Infections / Q000662:veterinary* / Q000821:virology; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D016865:Reassortant Viruses / Q000235:genetics / Q000302:isolation & purification*; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D013552:Swine; D013553:Swine Diseases / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral; D014764:Viral Proteins
keywords: pandemic A(H1N1) 2009; reassortant influenza virus; swine influenza virus