The 2009 Pandemic H1N1 D222G Hemagglutinin Mutation Alters Receptor Specificity and Increases Virulence in Mice but Not in Ferrets
The 2009 Pandemic H1N1 D222G Hemagglutinin Mutation Alters Receptor Specificity and Increases Virulence in Mice but Not in Ferrets
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DOI：
10.1093/infdis/jir483
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发表时间：
2011-10-01
影响因子：
6.4
通讯作者：
Boivin, Guy
中科院分区：
文献类型：
--
作者：
Abed, Yacine;Pizzorno, Andres;Boivin, Guy
背景。在2009年H1N1大流行（pH1N1）感染的严重病例中，在受体结合位点检测到D222G （H1编号）血凝素（HA）突变的频率较高。我们利用重组pH1N1病毒在体外和动物模型中研究了该突变的影响。重组HA突变体D222G是从野生型（WT）临床菌株中通过反向遗传和定点诱变产生的。测定MDCK和MDCK- α 2,6细胞的复制能力。抗原性通过HA抑制和微量中和试验进行表征。用人、鸡和再水解的火鸡红细胞（rbc）测定血凝素滴度。对小鼠和雪貂的毒力和接触传播力进行了分析。与WT相比，重组D222G病毒在MDCK中滴度显著提高，产生更大的病毒斑块，但在MDCK- α 2,6细胞中没有。该突变体也表现出使用表达α 2,6的红细胞的HA滴度显著降低。2个重组体抗原性相似。D222G突变病毒在小鼠中诱导更高的肺病毒滴度和肺泡炎症，而2个重组病毒在雪貂中具有相似的影响。D222G HA突变改变受体结合特异性，导致小鼠肺滴度升高。这可能导致报告的人类病死率较高。
Background. The D222G (H1 numbering) hemagglutinin ( HA) mutation within the receptor-binding site was detected with higher frequencies in severe cases of 2009 pandemic H1N1 (pH1N1) infections. We investigated the impact of this mutation in vitro and in animal models using recombinant pH1N1 viruses.Methods. The recombinant D222G HA mutant was generated from a wild-type (WT) clinical strain by using reverse genetics and site-directed mutagenesis. Replicative capacities were determined in MDCK and MDCK-alpha 2,6 cells. Antigenicity was characterized by HA inhibition and microneutralization assays. HA titers were determined using human, chicken, and resialylated turkey red blood cells (RBCs). Virulence and contact-transmissibility were analyzed in mice and ferrets.Results. The recombinant D222G virus grew to significantly higher titers and generated larger viral plaques compared with the WT in MDCK but not in MDCK-alpha 2,6 cells. The mutant also showed a significant reduction in HA titers using alpha 2,6-expressing RBCs. The 2 recombinants were antigenically similar. The D222G mutant virus induced higher lung viral titers and alveolar inflammation in mice whereas the 2 recombinants had similar impacts in ferrets.Conclusions. The D222G HA mutation alters receptor binding specificity, resulting in higher lung titers in mice. This could contribute to the higher case fatality rates reported in humans.