Biological properties of influenza A virus mutants with amino acid substitutions in the HA2 glycoprotein of the HA1/HA2 interaction region.
Biological properties of influenza A virus mutants with amino acid substitutions in the HA2 glycoprotein of the HA1/HA2 interaction region.
复制标题
HA1/HA2 相互作用区的 HA2 糖蛋白发生氨基酸取代的甲型流感病毒突变体的生物学特性。
DOI：
10.1099/jgv.0.001305
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Jakubcová L
中科院分区：
文献类型：
--
作者：
Jakubcová L
甲型流感病毒(IAV)通过受体依赖的内吞作用进入细胞。随后，低环境pH触发血凝素的构象变化，HA2糖蛋白(GP)的N端插入到内体膜上，导致融合孔形成和基因组vRNA释放到细胞质中。然而，膜融合的最适pH是宿主和病毒特有的，并会对病毒的致病性产生影响。我们制备了嗜神经性IAVA/WSN/33(H1N1)的突变体，即T642H(HA2编码位置，H1编码位置HA407，称为突变体‘’)，V662H(‘66’)(HA409)和一个带有两个AA替换的双突变体(‘D’)。假设这些取代会影响融合的最适pH。用荧光素酶测定融合活性的最适pH，并对病毒的生物学特性进行监测。突变体的体外复制能力和致病力与野生型相当()或更低(66，D)。而HA2突变体V662H和双突变体T642H、V662H使融合最大pH值偏低(从5.1~5.3)，而野生型和突变体的融合pH从5.4~5.6偏低。与野生型病毒感染的小鼠相比，66和D突变体的复制能力和致病性降低，并伴随着肺部感染后后期滴度的升高和脑内病毒RNA的升高。这些结果对理解流感病毒的致病性具有重要意义。
Influenza A viruses (IAVs) enter into cells by receptor-dependent endocytosis. Subsequently, conformational changes of haemagglutinin are triggered by low environmental pH and the N terminus of HA2 glycoprotein (gp) is inserted into the endosomal membrane, resulting in fusion pore formation and genomic vRNA release into the cytoplasm. However, the pH optimum of membrane fusion is host- and virus-specific and can have an impact on virus pathogenicity. We prepared mutants of neurotropic IAV A/WSN/33 (H1N1) with aa substitutions in HA2 gp at the site of HA1/HA2 interaction, namely T642H (HA2 numbering position 64, H1 numbering position HA407; referred to as mutant '64'), V662H ('66') (HA409); and a double mutant ('D') with two aa substitutions (T642H, V662H). These substitutions were hypothesized to influence the pH optimum of fusion. The pH optimum of fusion activity was measured by a luciferase assay and biological properties of viruses were monitored. Thein vitroandin vivoreplication ability and pathogenicity of mutants were comparable (64) or lower (66, D) than those of the wild-type virus. However, the HA2 mutation V662H and double mutation T642H, V662H shifted the fusion pH maximum to lower values (ranging from 5.1 to 5.3) compared to pH from 5.4 to 5.6 for the wild-type and 64 mutant. The decreased replication ability and pathogenicity of 66 and D mutants was accompanied by higher titres in late intervals post-infection in lungs, and viral RNA in brains compared to wild-type virus-infected mice. These results have implications for understanding the pathogenicity of influenza viruses.