title: Glycine at Position 622 in PB1 Contributes to the Virulence of H5N1 Avian Influenza Virus in Mice.
abstract: We isolated two H5N1 viruses, A/duck/Hunan/S4020/2008 (DK/08) and A/chicken/Guangxi/S2039/2009 (CK/09), from live-bird markets during routine surveillance and found that these two viruses are genetically similar but differ in their replication and virulence in mice. The CK/09 virus is lethal for mice with a 50% mouse lethal dose (MLD50) of 1.6 log10 50% egg infectious doses (EID50), whereas the DK/08 virus is nonpathogenic for mice with an MLD50 value of 6.2 log10 EID50. We explored the genetic basis of the virulence difference of these two viruses by generating a series of reassortant viruses and mutants in the lethal virus CK/09 background and evaluating their virulence in mice. We found that the PB1 gene of the DK/08 virus dramatically attenuated the virulence of the CK/09 virus and that the amino acid at position 622 in PB1 made an important contribution. We further demonstrated that the mutation of glycine (G) to aspartic acid (D) at position 622 in PB1 partially impaired the binding of PB1 to viral RNA, thereby dramatically decreasing the polymerase activity and attenuating H5N1 virus virulence in mice. Our results identify a novel virulence-related marker of H5N1 influenza viruses and provide a new target for live attenuated vaccine development.
  
  
  OBJECTIVE
  H5N1 avian influenza viruses have caused the deaths of nearly 60% of the humans that they have infected since 1997 and clearly represent a threat to public health. A thorough understanding of the genetic basis of virulence determinants will provide important insights for antiviral drug and live attenuated vaccine development. Several virulence-related markers in the PB2, PA, M1, and NS1 proteins of H5N1 viruses have been identified. In this study, we isolated two H5N1 avian influenza viruses that are genetically similar but differ in their virulence in mice, and we identified a new virulence-related marker in the PB1 gene. We found that the mutation of glycine (G) to aspartic acid (D) at position 622 in PB1 partially impairs the binding of PB1 to viral RNA, thereby attenuating H5N1 virus virulence in mice. This newly identified virulence-related marker could be applied to the development of live attenuated vaccines against H5N1 influenza.
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.
authors.forename: Zeng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.
authors.forename: Guohua
authors.initials: G
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.
authors.forename: Huihui
authors.initials: H
authors.lastname: Kong
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.
authors.forename: Shiyu
authors.initials: S
authors.lastname: Tao
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.
authors.forename: Changyao
authors.initials: C
authors.lastname: Li
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.
authors.forename: Liling
authors.initials: L
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.
authors.forename: Yuntao
authors.initials: Y
authors.lastname: Guan
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China chenhualan@caas.cn.
authors.forename: Hualan
authors.initials: H
authors.lastname: Chen
mesh_terms: D000818:Animals; D005260:Female; D005998:Glycine / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D007928:Lethal Dose 50; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000473:pathology* / Q000821:virology; D016865:Reassortant Viruses / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology; D059386:Reverse Genetics; D016019:Survival Analysis; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D014764:Viral Proteins; D037521:Virulence Factors; C077346:influenza virus polymerase basic protein 1; D005998:Glycine