甲型流感病毒宿主嗜性相关位点的多态性研究

Polymorphisms of host tropism relating amino acid sites in influenza A virus

【目的】以甲型流感病毒(IAV)毒株的完整内部蛋白编码基因为基础,发现并分析IAV传播过程中出现的影响宿主嗜性类型的单个或相互作用的关键氨基酸位点,为研究IAV的人类宿主适应性突变提供依据。【方法】在全球流感共享数据库(GISAID)EpiFluTM数据库中,根据查询条件获得43671个IAV毒株对应的6个内部基因节段全长核苷酸序列,通过质控与去冗余后保留698个嗜人类亚型(HU)和1266个嗜禽类亚型(AV)代表株,使用R代码比较2种嗜性类别代表株的氨基酸共义序列,获得氨基酸差异位点及其多态性,并对差异位点进行多位点组合分析。【结果】AV与HU中H1N1、H3N2亚型代表株分别进行共有序列比对,各发现49个、57个保守差异位点。差异位点的多位点组合分析,在HU与AV间分别发现79个三位点组合与65个四位点组合。共有11个保守差异位点同时存在于2种组合内:PB2蛋白的271、684位点;PB1蛋白的336、486、581、621位点;PA蛋白的204、356位点;NP蛋白的33、305、357位点;M1和NS1中未发现符合条件的差异位点。【结论】IAV的嗜人和嗜禽类毒株间在PB2、PB1、PA与NP蛋白中存在若干保守氨基酸差异位点,这些位点彼此间可能存在一定形式的互相作用并进而形成特定的组合,共同(而非各自)决定着病毒的宿主嗜性。

[Objective]To discover and analyze single or several correlative key amino acid sites that influence the host tropism during the influenza A virus(IAV)infection based on complete internal protein gene segments of IAV strains,and to provide evidence for the study of human host-adaptive mutations of IAV.[Methods]The full-length nucleotide sequences of 43671 IAV strains containing 6 complete internal gene segments were downloaded from the GISAID EpiFluTM database,and 698 human-tropic(HU)and 1266 avian-tropic(AV)representative strains were included.The consensus coding sequences of the representative strains from the amphitropic category were compared by R script,and the differential amino acid sites and their polymorphisms were then obtained.The multi-site combination analysis of differential sites was conducted with R script.[Results]A total of 49 and 57 conserved differential sites were obtained from the consensus sequence comparison between AV and H1N1(subtype from HU),and comparison between AV and H3N2(another subtype from HU),separately.79 and 65 multisite combinations were found between HU and AV strains through 3 and 4 sites combination analysis,respectively,and a total of 11 conserved sites were involved:site 271 and 684 in PB2;site 336,486,581 and 621 in PB1;site 204 and 356 in PA;site 33,305 and 357 in NP.No eligible differential sites were found in M1 and NS1.[Conclusion]Several conserved amino acid differential sites,between HU and AV strains of IAV,are found in PB2,PB1,PA and NP proteins.Instead of working as single units,these sites may have interactions,forming specific amino acid combinations that determine the host tropism of IAV collectively.