PB2 Residue 271 Plays a Key Role in Enhanced Polymerase Activity of Influenza A Viruses in Mammalian Host Cells
PB2 Residue 271 Plays a Key Role in Enhanced Polymerase Activity of Influenza A Viruses in Mammalian Host Cells
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DOI：
10.1128/jvi.02642-09
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发表时间：
2010-05-01
影响因子：
5.4
通讯作者：
Takimoto, Toru
中科院分区：
文献类型：
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作者：
Bussey, Kendra A.;Bousse, Tatiana L.;Takimoto, Toru
人类直接感染高致病性H5 N1禽流感病毒表明，病毒突变是新型人类A型流感病毒出现的一种机制。虽然聚合酶复合体是已知的宿主适应的关键组成部分，突变，提高禽流感病毒在哺乳动物宿主中的聚合酶活性没有得到充分的表征。甲型流感病毒分离株的基因组比较已经鉴定出流感蛋白中对人或禽病毒特异性的高度保守残基，包括PB 2中的10个残基。我们表征了在这些保守的PB 2残基处含有禽-人突变的禽聚合酶复合物的活性，并发现除了E627 K突变之外，PB 2突变T271 A增强了人细胞中的聚合酶活性。我们证实了T271 A突变的影响，使用重组WSN病毒含有禽NP和聚合酶基因与野生型（WT）或突变PB 2。在体外哺乳动物细胞中，与WT相比，271 A病毒显示出增强的生长。与627 K突变体相比，271 A突变体在小鼠中没有显著增加病毒致病性，但它确实增加了肺病毒滴度。此外，细胞浸润在271 A感染小鼠的肺中比WT小鼠的肺中更明显。有趣的是，2009年大流行H1N1流感病毒的禽源性PB 2具有271 A。对A/加州/04/2009（H1 N1）和相应PB 2突变体的聚合酶活性的表征表明，哺乳动物细胞中大流行毒株的高聚合酶活性部分依赖于271 A。我们的研究结果清楚地表明PB 2氨基酸271对哺乳动物宿主中增强的聚合酶活性和病毒生长的贡献。
The direct infection of humans with highly pathogenic avian H5N1 influenza viruses has suggested viral mutation as one mechanism for the emergence of novel human influenza A viruses. Although the polymerase complex is known to be a key component in host adaptation, mutations that enhance the polymerase activity of avian viruses in mammalian hosts are not fully characterized. The genomic comparison of influenza A virus isolates has identified highly conserved residues in influenza proteins that are specific to either human or avian viruses, including 10 residues in PB2. We characterized the activity of avian polymerase complexes containing avian-to-human mutations at these conserved PB2 residues and found that, in addition to the E627K mutation, the PB2 mutation T271A enhances polymerase activity in human cells. We confirmed the effects of the T271A mutation using recombinant WSN viruses containing avian NP and polymerase genes with wild-type (WT) or mutant PB2. The 271A virus showed enhanced growth compared to that of the WT in mammalian cells in vitro. The 271A mutant did not increase viral pathogenicity significantly in mice compared to that of the 627K mutant, but it did enhance the lung virus titer. Also, cell infiltration was more evident in lungs of 271A-infected mice than in those of the WT. Interestingly, the avian-derived PB2 of the 2009 pandemic H1N1 influenza virus has 271A. The characterization of the polymerase activity of A/California/04/2009 (H1N1) and corresponding PB2 mutants indicates that the high polymerase activity of the pandemic strain in mammalian cells is, in part, dependent on 271A. Our results clearly indicate the contribution of PB2 amino acid 271 to enhanced polymerase activity and viral growth in mammalian hosts.