Virological Characterization of Residue 216 on PB1 Protein in Replicase of Influenza A Virus

• Main Authors: Huang, Po-Yu, 黃博煜
• Other Authors: Liao, Ching-Len
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/43166482390482649091

碩士 === 國防醫學院 === 微生物及免疫學研究所 === 100 === Influenza A virus belongs to Orthomyxoviridae family, which is enveloped, negative-sense RNA viruses with eight segmented genomes. Each RNA genome is packaged into ribonucleoprotein (RNP) complex containing nucleoprotein (NP) and the trimeric RNA-dependent RNA polymerase (RdRP), which is comprises of PA, PB1 and PB2 subunits. Among these, PB1 contains the polymerase catalytic domain which is essential for virus genome replication and mRNA transcription. According to previous epidemiology study, residue 216 on PB1 protein of influenza A viruses isolated from different infected hosts exhibits species-specific signature; that is, serine in avian-isolated influenza virus, either serine or glycine in swine isolates, and predominantly glycine in 2009 human pandemic strains. To further study the potential role of such signatures in virus replication capability, replicase fidelity and virulence in mice, we generated mutant viruses using laboratory influenza A virus strains of WSN33 and PR8, as well as TW126 isolated in Taiwan in 2009. We found that PB1S216G substitution attenuated viral virulence in mice of both WSN33 and PR8, whereas PB1G216S enhanced the virulence of PR8/TW126PB1 reassortment virus. There is no apparent difference in viral growth of these viruses under culture condition. However, we found PB1S216G resulted in higher accumulative mutation index (AMI) of replicase complex assayed by mini-replicon system, and vice versa for lower AMI in PB1G216S mutants. We therefore hypothesized that substitution at this point affects viral virulence in mice through altering influenza RdRP fidelity and revealed a potential role of residue 216 on PB1 for virulence determination.