title: PAN substitutions A37S, A37S/I61T and A37S/V63I attenuate the replication of H7N7 influenza A virus by impairing the polymerase and endonuclease activities.
abstract: Substitutions in the PA N-terminus (PAN) of influenza A viruses are associated with viral pathogenicity. During our previous study, which identified PAN-V63I and -A37S/I61T/V63I/V100A substitutions as virulence determinants, we observed a severe decrease in virus growth and transcription/replication capacity posed by PAN-A37S/V100A substitution. To further delineate the significance of substitutions at these positions, we generated mutant H7N7 viruses bearing the substitutions PAN-A37S, -A37S/I61T, -A37S/V63I, -V100A, -I61T/V100A and -V63I/V100A by reverse genetics. Our results showed that all mutant viruses except PAN-V100A showed a significantly reduced growth capability in infected cells. At the same time, the PAN-A37S, -A37S/I61T and -A37S/V63I mutant viruses displayed decreased viral transcription and replication by diminishing virus RNA synthesis activity. Biochemical assays indicated that the substitutions PAN-A37S, -A37S/I61T and -A37S/V63I suppressed the polymerase and endonuclease activities when compared with those of the wild-type. Together, our results demonstrated that the PAN-A37S, -A37S/I61T and -A37S/V63I substitutions contributed to a decreased pathogenicity of avian H7N7 influenza A virus.
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Meng
authors.initials: M
authors.lastname: Hu
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Shuofeng
authors.initials: S
authors.lastname: Yuan
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Zi-Wei
authors.initials: ZW
authors.lastname: Ye
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Kailash
authors.initials: K
authors.lastname: Singh
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Cun
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Huiping
authors.initials: H
authors.lastname: Shuai
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Ng
authors.initials: N
authors.lastname: Fai
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Billy K C
authors.initials: BKC
authors.lastname: Chow
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong SAR, PR China.|State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Hin
authors.initials: H
authors.lastname: Chu
authors.affiliation: Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong SAR, PR China.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong SAR, PR China.|Department of Microbiology, The University of Hong Kong, Hong Kong SAR, PR China.|State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Bo-Jian
authors.initials: BJ
authors.lastname: Zheng
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001717:Birds; D004285:Dogs; D053126:Influenza A Virus, H7N7 Subtype / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000821:virology*; D061985:Madin Darby Canine Kidney Cells; D000072417:Protein Domains; D012367:RNA, Viral / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication / Q000235:genetics
chemical_list: C061290:PA protein, influenza viruses; D012367:RNA, Viral; D014764:Viral Proteins; D037521:Virulence Factors; D012324:RNA-Dependent RNA Polymerase