The PA Protein Directly Contributes to the Virulence of H5N1 Avian Influenza Viruses in Domestic Ducks
The PA Protein Directly Contributes to the Virulence of H5N1 Avian Influenza Viruses in Domestic Ducks
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DOI：
10.1128/jvi.01975-10
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发表时间：
2011-03-01
影响因子：
5.4
通讯作者：
Chen, Hualan
中科院分区：
文献类型：
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作者：
Song, Jiasheng;Feng, Huapeng;Chen, Hualan
H5N1 禽流感病毒（AIV）在自然界中传播期间，已经获得了杀死其自然宿主、野鸟和鸭子的能力。这种毒力增加的遗传决定因素在很大程度上尚不清楚。在这项研究中，我们比较了两种基因相似的 H5N1 AIV，A/duck/Hubei/49/05 (DK/49) 和 A/goose/Hubei/65/ 05 (GS/65)，它们对鸡具有致命性，但对鸭的毒力水平不同。为了探索这种毒力差异的遗传基础，我们产生了这两种病毒的一系列重配体和突变体。 GS/65背景下带有DK/49 PA基因的重配体的毒力相对于GS/65病毒增加了105倍。 PA 中两个氨基酸 S224P 和 N383D 的取代导致了高毒力表型。 PA中的氨基酸224P增加了病毒在鸭胚成纤维细胞中的复制，PA中的氨基酸383D增加了鸭胚成纤维细胞中的聚合酶活性并延迟了病毒感染细胞核中PA和PB1聚合酶亚基的积累。我们的结果提供了强有力的证据，证明聚合酶 PA 亚基是鸭体内 H5N1 AIV 的毒力因子。
During their circulation in nature, H5N1 avian influenza viruses (AIVs) have acquired the ability to kill their natural hosts, wild birds and ducks. The genetic determinants for this increased virulence are largely unknown. In this study, we compared two genetically similar H5N1 AIVs, A/duck/Hubei/49/05 (DK/49) and A/goose/Hubei/65/ 05 (GS/65), that are lethal for chickens but differ in their virulence levels in ducks. To explore the genetic basis for this difference in virulence, we generated a series of reassortants and mutants of these two viruses. The virulence of the reassortant bearing the PA gene from DK/49 in the GS/65 background increased 105-fold relative to that of the GS/65 virus. Substitution of two amino acids, S224P and N383D, in PA contributed to the highly virulent phenotype. The amino acid 224P in PA increased the replication of the virus in duck embryo fibroblasts, and the amino acid 383D in PA increased the polymerase activity in duck embryo fibroblasts and delayed the accumulation of the PA and PB1 polymerase subunits in the nucleus of virus-infected cells. Our results provide strong evidence that the polymerase PA subunit is a virulence factor for H5N1 AIVs in ducks.