Adaptation of Pandemic H1N1 Influenza Viruses in Mice
Adaptation of Pandemic H1N1 Influenza Viruses in Mice
复制标题
DOI：
10.1128/jvi.00159-10
复制
发表时间：
2010-09-01
影响因子：
5.4
通讯作者：
Webby, Richard J.
中科院分区：
文献类型：
--
作者：
Ilyushina, Natalia A.;Khalenkov, Alexey M.;Webby, Richard J.
2009年甲型流感大流行病毒能够充分适应人类的分子机制在很大程度上是未知的。随后人类感染新型H1N1流感病毒，促使人们对大流行性流感病毒在哺乳动物中宿主范围和致病性的分子决定因素进行调查。为了解决这一问题，我们评估了A/CA/04/09 （H1N1）和A/TN/1-560/09 （H1N1）分离株在新的哺乳动物宿主中通过促进小鼠适应而增加毒力的遗传基础，这两种分离株对小鼠不致命。由此产生的小鼠肺适应变异在卵子中表现出显著增强的生长特征，扩展的肺外组织亲和性和小鼠致病性。除A/TN/1-560/09-MA2外，所有小鼠适应病毒在细胞中的生长速度和滴度均高于原菌株。我们发现核糖核蛋白（RNP）复合体（PB2 E158G/A、PA L295P、NP D101G和NP H289Y）和血凝素（HA）糖蛋白（K119N、G155E、S183P、R221K和D222G）的10个氨基酸变化控制了大流行分离物小鼠毒力的增强。在适应过程中获得的HA突变通过增强与α 2,3的结合而降低与α 2,6唾液酸受体的结合来影响病毒受体的特异性。PB2 E158G/A和PA L295P氨基酸的替换显著增强了小鼠适应H1N1变异的转录和复制活性。综上所述，我们的研究结果表明，优化受体特异性和病毒聚合酶组分与宿主细胞因子相互作用的变化是大流行性流感病毒在小鼠中获得最佳竞争优势的主要机制。因此，这些毒力调节剂可能是早期进化的驱动因素，为2009年哺乳动物中的新型病毒铺平了道路。
The molecular mechanism by which pandemic 2009 influenza A viruses were able to sufficiently adapt to humans is largely unknown. Subsequent human infections with novel H1N1 influenza viruses prompted an investigation of the molecular determinants of the host range and pathogenicity of pandemic influenza viruses in mammals. To address this problem, we assessed the genetic basis for increased virulence of A/CA/04/09 (H1N1) and A/TN/1-560/09 (H1N1) isolates, which are not lethal for mice, in a new mammalian host by promoting their mouse adaptation. The resulting mouse lung-adapted variants showed significantly enhanced growth characteristics in eggs, extended extrapulmonary tissue tropism, and pathogenicity in mice. All mouse-adapted viruses except A/TN/1-560/09-MA2 grew faster and to higher titers in cells than the original strains. We found that 10 amino acid changes in the ribonucleoprotein (RNP) complex (PB2 E158G/A, PA L295P, NP D101G, and NP H289Y) and hemagglutinin (HA) glycoprotein (K119N, G155E, S183P, R221K, and D222G) controlled enhanced mouse virulence of pandemic isolates. HA mutations acquired during adaptation affected viral receptor specificity by enhancing binding to alpha 2,3 together with decreasing binding to alpha 2,6 sialyl receptors. PB2 E158G/A and PA L295P amino acid substitutions were responsible for the significant enhancement of transcription and replication activity of the mouse-adapted H1N1 variants. Taken together, our findings suggest that changes optimizing receptor specificity and interaction of viral polymerase components with host cellular factors are the major mechanisms that contribute to the optimal competitive advantage of pandemic influenza viruses in mice. These modulators of virulence, therefore, may have been the driving components of early evolution, which paved the way for novel 2009 viruses in mammals.