Glycine at Position 622 in PB1 Contributes to the Virulence of H5N1 Avian Influenza Virus in Mice.
Glycine at Position 622 in PB1 Contributes to the Virulence of H5N1 Avian Influenza Virus in Mice.
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DOI：
10.1128/jvi.02387-15
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发表时间：
2016-02-15
影响因子：
5.4
通讯作者：
Chen H
中科院分区：
文献类型：
--
作者：
Feng X;Wang Z;Shi J;Deng G;Kong H;Tao S;Li C;Liu L;Guan Y;Chen H
我们在日常监测活禽市场中分离到两株H5 N1病毒，A/鸭/湖南/S4020/2008（DK/08）和A/鸡/广西/S2039/2009（CK/09），发现这两种病毒在遗传上相似，但在小鼠中的复制和毒力不同。CK/09病毒对小鼠具有致死性，半数小鼠致死剂量（MLD 50）为1.6 log 10半数鸡胚感染剂量（EID 50），而DK/08病毒对小鼠无致病性，MLD 50值为6.2 log 10 EID 50。我们通过在致死病毒CK/09背景下产生一系列的回复病毒和突变体，并在小鼠中评估它们的毒力，来探索这两种病毒毒力差异的遗传基础。我们发现DK/08病毒的PB 1基因显著地减弱了CK/09病毒的毒力，并且PB 1中第622位的氨基酸做出了重要贡献。我们进一步证明PB 1中622位甘氨酸（G）突变为天冬氨酸（D）部分削弱了PB 1与病毒RNA的结合，从而显著降低了聚合酶活性并减弱了H5 N1病毒在小鼠中的毒力。我们的研究结果确定了一种新的与H5 N1流感病毒毒力相关的标志物，并为减毒活疫苗的开发提供了一个新的靶点。自1997年以来，H5 N1禽流感病毒已导致近60%的人死亡，显然对公共卫生构成威胁。深入了解毒力决定因子的遗传基础，将为抗病毒药物和减毒活疫苗的开发提供重要的参考。在H5 N1病毒的PB 2、PA、M1和NS 1蛋白中已经鉴定出几种与毒力相关的标记。在这项研究中，我们分离了两种H5 N1禽流感病毒，它们在遗传上相似，但在小鼠中的毒力不同，我们在PB 1基因中鉴定了一个新的毒力相关标记。我们发现PB 1中第622位的甘氨酸（G）突变为天冬氨酸（D）部分削弱了PB 1与病毒RNA的结合，从而减弱了H5 N1病毒在小鼠中的毒力。这一新发现的毒力相关标志物可应用于H5 N1流感减毒活疫苗的开发。
We isolated two H5N1 viruses, A/duck/Hunan/S4020/2008 (DK/08) and A/chicken/Guangxi/S2039/2009 (CK/09), from live-bird markets during routine surveillance and found that these two viruses are genetically similar but differ in their replication and virulence in mice. The CK/09 virus is lethal for mice with a 50% mouse lethal dose (MLD50) of 1.6 log10 50% egg infectious doses (EID50), whereas the DK/08 virus is nonpathogenic for mice with an MLD50 value of 6.2 log10 EID50. We explored the genetic basis of the virulence difference of these two viruses by generating a series of reassortant viruses and mutants in the lethal virus CK/09 background and evaluating their virulence in mice. We found that the PB1 gene of the DK/08 virus dramatically attenuated the virulence of the CK/09 virus and that the amino acid at position 622 in PB1 made an important contribution. We further demonstrated that the mutation of glycine (G) to aspartic acid (D) at position 622 in PB1 partially impaired the binding of PB1 to viral RNA, thereby dramatically decreasing the polymerase activity and attenuating H5N1 virus virulence in mice. Our results identify a novel virulence-related marker of H5N1 influenza viruses and provide a new target for live attenuated vaccine development. IMPORTANCE H5N1 avian influenza viruses have caused the deaths of nearly 60% of the humans that they have infected since 1997 and clearly represent a threat to public health. A thorough understanding of the genetic basis of virulence determinants will provide important insights for antiviral drug and live attenuated vaccine development. Several virulence-related markers in the PB2, PA, M1, and NS1 proteins of H5N1 viruses have been identified. In this study, we isolated two H5N1 avian influenza viruses that are genetically similar but differ in their virulence in mice, and we identified a new virulence-related marker in the PB1 gene. We found that the mutation of glycine (G) to aspartic acid (D) at position 622 in PB1 partially impairs the binding of PB1 to viral RNA, thereby attenuating H5N1 virus virulence in mice. This newly identified virulence-related marker could be applied to the development of live attenuated vaccines against H5N1 influenza.