title: Antigenic and genetic characterization of H9N2 swine influenza viruses in China.
abstract: As pigs are susceptible to infection with both avian and human influenza A viruses, they have been proposed to be an intermediate host for the generation of pandemic virus through reassortment. Antigenic and genetic characterization was performed for five swine H9N2 influenza viruses isolated from diseased pigs from different farms. The haemagglutinin (HA) antigenicity of swine H9N2 viruses was different from that of chicken H9N2 viruses prevalent in northern China. Genetic analysis revealed that all five isolates had an RLSR motif at the cleavage site of HA, which was different from those of A/duck/Hong Kong/Y280/97 (Dk/HK/Y280/97)-like viruses established in chickens in China. Phylogenetic analyses indicated that the five swine H9N2 viruses formed novel HA and neuraminidase sublineages that were related closely to those of earlier chicken H9 viruses and were also consistent with the extent of the observed antigenic variation. The six internal genes of the isolates possessed H5N1-like sequences, indicating that they were reassortants of H9 and H5 viruses. The present results indicate that avian to porcine interspecies transmission of H9N2 viruses might have resulted in the generation of viruses with novel antigenic and genetic characteristics; therefore, surveillance of swine influenza should be given a high priority.
authors.affiliation: Laboratory of Infectious Diseases, College of Veterinary Medicine, State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.
authors.forename: Yan L
authors.initials: YL
authors.lastname: Cong
authors.affiliation: Laboratory of Infectious Diseases, College of Veterinary Medicine, State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.
authors.forename: Juan
authors.initials: J
authors.lastname: Pu
authors.affiliation: Laboratory of Infectious Diseases, College of Veterinary Medicine, State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.
authors.forename: Qin F
authors.initials: QF
authors.lastname: Liu
authors.affiliation: Laboratory of Infectious Diseases, College of Veterinary Medicine, State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Wang
authors.affiliation: Laboratory of Infectious Diseases, College of Veterinary Medicine, State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.
authors.forename: Guo Z
authors.initials: GZ
authors.lastname: Zhang
authors.affiliation: Laboratory of Infectious Diseases, College of Veterinary Medicine, State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.
authors.forename: Xing L
authors.initials: XL
authors.lastname: Zhang
authors.affiliation: China Animal Health and Epidemiology Center, Qingdao 266032, PR China.
authors.forename: Wei X
authors.initials: WX
authors.lastname: Fan
authors.affiliation: Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, ON, Canada.
authors.forename: Earl G
authors.initials: EG
authors.lastname: Brown
authors.affiliation: Laboratory of Infectious Diseases, College of Veterinary Medicine, State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.
authors.forename: Jin H
authors.initials: JH
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000956:Antigens, Viral / Q000235:genetics*; D002645:Chickens / Q000821:virology; D002681:China; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000276:immunology; D006801:Humans; D053127:Influenza A Virus, H9N2 Subtype / Q000145:classification / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D005585:Influenza in Birds / Q000635:transmission / Q000821:virology; D007251:Influenza, Human / Q000635:transmission / Q000821:virology; D008969:Molecular Sequence Data; D009976:Orthomyxoviridae Infections / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D010802:Phylogeny; D016865:Reassortant Viruses / Q000145:classification / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D034421:Sus scrofa / Q000821:virology; D013552:Swine; D013553:Swine Diseases / Q000635:transmission / Q000821:virology*; D015047:Zoonoses / Q000635:transmission / Q000821:virology
chemical_list: D000956:Antigens, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus