title: Adaptive mutations in PB2 gene contribute to the high virulence of a natural reassortant H5N2 avian influenza virus in mice.
abstract: The highly pathogenic A/chicken/Hebei/1102/2010 (HB10) H5N2 virus is a natural reassortant derived from circulating H5N1 and endemic H9N2 avian influenza viruses (AIV). To evaluate the potential of its interspecies transmission, we previously serially passaged the non-virulent HB10 virus in the mouse lung and obtained a high virulence variant (HB10-MA). Genomic sequencing revealed five mutations (HA-S227N, PB2-Q591K, PB2-D701N, PA-I554V and NP-R351K) that distinguished HB10-MA virus from its parental HB10 virus. In this study, we further investigated the molecular basis for the enhanced virulence of HB10-MA in mice. By generating a series of reassortants between the two viruses and evaluating their virulence in mice, we found that both PB2 and PA genes contribute to the high virulence of HB10-MA in mice, whereas PB2 gene carrying the 591K and/or 701N had a dominant function. In addition, the two amino acids showed a cumulative effect on the virulence, virus replication, and polymerase activity of HB10 or HB10-MA. Therefore, our results collectively emphasized the crucial role of PB2 gene, particularly the paired mutations of Q591K and D701N in the host adaptation of the novel reassortant H5N2 AIV in mammals, which may provide helpful insights into the pathogenic potential of emerging AIV in human beings.
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Qunhui
authors: Q
authors: Li
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Xuan
authors: X
authors: Wang
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Zhongtao
authors: Z
authors: Sun
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Jiao
authors: J
authors: Hu
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Zhao
authors: Z
authors: Gao
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Xiaoli
authors: X
authors: Hao
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Juan
authors: J
authors: Li
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Huimou
authors: H
authors: Liu
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Xiaoquan
authors: X
authors: Wang
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Min
authors: M
authors: Gu
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, Jiangsu 225009, China. Electronic address: xxl@yzu.edu.cn.
authors: Xiulong
authors: X
authors: Xu
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors: Xiaowen
authors: X
authors: Liu
authors: Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, Jiangsu 225009, China. Electronic address: xfliu@yzu.edu.cn.
authors: Xiufan
authors: X
authors: Liu
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D002645:Chickens; D005260:Female; D016679:Genome, Viral; D053125:Influenza A Virus, H5N2 Subtype / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000821:virology; D008807:Mice, Inbred BALB C; D020125:Mutation, Missense; D009976:Orthomyxoviridae Infections / Q000821:virology; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics* / Q000378:metabolism; D016865:Reassortant Viruses / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity*; D059386:Reverse Genetics; D017422:Sequence Analysis, DNA; D012692:Serial Passage; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C061290:PA protein, influenza viruses; C057027:PB2 protein, Influenzavirus A; D014764:Viral Proteins; D037521:Virulence Factors; D012324:RNA-Dependent RNA Polymerase
keywords: Avian influenza virus; H5N2; H7N9; Mouse-adapted; PB2; Pathogenicity; Reassortant