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Elgendy EM, Arai Y, Kawashita N, Isobe A, Daidoji T, Ibrahim MS, Ono T, Takagi T, Nakaya T, Matsumoto K, Watanabe Y. Double mutations in the H9N2 avian influenza virus PB2 gene act cooperatively to increase viral host adaptation and replication for human infections. J Gen Virol 2021; 102. [PMID: 34061017 DOI: 10.1099/jgv.0.001612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Avian H9N2 influenza viruses in East Asia are genetically diversified and multiple genotypes (A-W) have been established in poultry. Genotype S strains are currently the most prevalent strains, have caused many human infections and pose a public health threat. In this study, human adaptation mutations in the PB2 polymerase in genotype S strains were identified by database screening. Several PB2 double mutations were identified that acted cooperatively to produce higher genotype S virus polymerase activity and replication in human cells than in avian cells and to increase viral growth and virulence in mice. These mutations were chronologically and phylogenetically clustered in a new group within genotype S viruses. Most of the relevant human virus isolates carry the PB2-A588V mutation together with another PB2 mutation (i.e. K526R, E627V or E627K), indicating a host adaptation advantage for these double mutations. The prevalence of PB2 double mutations in human H9N2 virus isolates has also been found in genetically related human H7N9 and H10N8 viruses. These results suggested that PB2 double mutations in viruses in the field acted cooperatively to increase human adaptation of the currently prevalent H9N2 genotype S strains. This may have contributed to the recent surge of H9N2 infections and may be applicable to the human adaptation of several other avian influenza viruses. Our study provides a better understanding of the human adaptation pathways of genetically related H9N2, H7N9 and H10N8 viruses in nature.
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Affiliation(s)
- Emad Mohamed Elgendy
- Department of Infectious Diseases, Graduate School of Medical Sciences, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Damanhour University, Damanhour, Egypt
| | - Yasuha Arai
- Department of Infectious Diseases, Graduate School of Medical Sciences, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Norihito Kawashita
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan.,Faculty of Science and Engineering, Kindai University, Osaka, Japan
| | - Ayana Isobe
- Department of Infectious Diseases, Graduate School of Medical Sciences, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Tomo Daidoji
- Department of Infectious Diseases, Graduate School of Medical Sciences, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Madiha Salah Ibrahim
- Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Damanhour University, Damanhour, Egypt
| | - Takao Ono
- The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
| | - Tatsuya Takagi
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Takaaki Nakaya
- Department of Infectious Diseases, Graduate School of Medical Sciences, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Kazuhiko Matsumoto
- The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
| | - Yohei Watanabe
- Department of Infectious Diseases, Graduate School of Medical Sciences, Kyoto Prefectural University of Medicine, Kyoto, Japan
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