title: Molecular characterization of highly pathogenic H5N1 avian influenza A viruses isolated from raccoon dogs in China.
abstract: BACKGROUND
  The highly pathogenic avian influenza H5N1 virus can infect a variety of animals and continually poses a threat to animal and human health. While many genotypes of H5N1 virus can be found in chicken, few are associated with the infection of mammals. Characterization of the genotypes of viral strains in animal populations is important to understand the distribution of different viral strains in various hosts. This also facilitates the surveillance and detection of possible emergence of highly pathogenic strains of specific genotypes from unknown hosts or hosts that have not been previously reported to carry these genotypes.
  
  
  RESULTS
  Two H5N1 isolates were obtained from lung samples of two raccoon dogs that had died from respiratory disease in China. Pathogenicity experiments showed that the isolates were highly pathogenic to chicken. To characterize the genotypes of these viruses, their genomic sequences were determined and analyzed. The genetic contents of these isolates are virtually identical and they may come from the same progenitor virus. Phylogenetic analysis indicated that the isolates were genetically closely related to genotype V H5N1 virus, which was first isolated in China in 2003, and were distinct from the dominant virus genotypes (e.g. genotype Z) of recent years. The isolates also contain a multibasic amino acid motif at their HA cleavage sites and have an E residue at position 627 of the PB2 protein similar to the previously-identified avian viruses.
  
  
  CONCLUSIONS
  This is the first report that genotype V H5N1 virus is found to be associated with a mammalian host. Our results strongly suggest that genotype V H5N1 virus has the ability to cross species barriers to infect mammalian animals. These findings further highlight the risk that avian influenza H5N1 virus poses to mammals and humans, which may be infected by specific genotypes that are not known to infect these hosts.
authors.affiliation: Jiangsu CDC-Nanjing University Joint Institute of Virology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China.
authors.forename: Xian
authors.initials: X
authors.lastname: Qi
authors.forename: Xihan
authors.initials: X
authors.lastname: Li
authors.forename: Paul
authors.initials: P
authors.lastname: Rider
authors.forename: Weixing
authors.initials: W
authors.lastname: Fan
authors.forename: Hongwei
authors.initials: H
authors.lastname: Gu
authors.forename: Longtao
authors.initials: L
authors.lastname: Xu
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Yang
authors.forename: Sangwei
authors.initials: S
authors.lastname: Lu
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.forename: Fenyong
authors.initials: F
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D005838:Genotype; D006388:Hemagglutinins / Q000378:metabolism; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000821:virology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011201:Poultry Diseases / Q000821:virology*; D046031:Raccoon Dogs / Q000821:virology*; D012141:Respiratory Tract Infections / Q000662:veterinary* / Q000821:virology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D006388:Hemagglutinins