埃博拉病毒包膜糖蛋白二级结构及B细胞表位的预测

Prediction of secondary structure and B cell epitope of glycoprotein of Ebolavirus

目的预测并分析从2014年西非埃博拉出血热暴发地区感染患者分离的扎伊尔型病毒株包膜糖蛋白（glycoprotein,GP）的二级结构及B细胞表位。方法通过Gen Bank搜索近期公布的分离自西非地区的扎伊尔型埃博拉病毒株基因组,获得GP1、GP2和s GP 3种包膜糖蛋白的基因及氨基酸序列,采用互联网服务器在线预测其二级结构及B细胞表位,并分析蛋白的各种氨基酸组成比例及可能的蛋白结合位点,通过亲/疏水性等参数判断氨基酸序列中可能暴露在蛋白结构表面或隐藏在内部的区段。结果在编码GP1、GP2和s GP的氨基酸中,占组成比例最多的均为苏氨酸。GP1和s GP可能的蛋白结合位点较多,且整个蛋白暴露于表面的区域和隐藏区域呈均匀相间分布;GP2结构较前二者特殊,存在一个暴露在蛋白结构表面的大片段的无序结构区域。GP1 N-末端第20～37和166～186区段,GP2 N-末端第361～379区段,s GP N-末端第20～37和166～185区段,可能为跨膜螺旋结构。s GP可能存在4个含有二硫键的区域。B细胞表位分析结果显示,GP1和GP2中疏水区域主要集中在N-末端第1～325位氨基酸之间;亲水区域主要集中在N-末端第326～676位氨基酸之间;亲水与疏水区域分界明显,几乎无交叉;可能存在2个线性表位,分别位于N-末端第324～450、461～676区段;预测共存在25个可能形成构象表位的氨基酸位点或序列,其中可能性在90%以上的位点或序列有6个。结论通过对此次流行于西非的埃博拉病毒包膜糖蛋白的二级结构及可能性B细胞表位的预测,为实验确定埃博拉病毒包膜糖蛋白的结构与功能、B细胞表位免疫识别以及埃博拉病毒预防、治疗和诊断制品的研发提供了参考。

Objective To predict and analyze the secondary structure and B cell epitope of glycoprotein （GP） of Ebolavirus strain of type Zaire isolated from patients in West Africa with an outbreak in 2014. Methods The genomes of Ebolavirus strain of type Zaire isolated from West Africa published recently were searched from GenBank to obtain the gene and amino acid sequences of GP1, GP2 and sGP, based on which the amino acid composition ratio and possible protein binding site were analyzed, and the possibly exposed and buried regions in amino acid sequence were judged by hydrophilicity/hydrophobicity parameters. Results Threonine occupied the maxiumum ratio of amino acids encoding GP1, GP2 and sGP. The protein binding sites of GP1 and sGP were abundant, while the exposed and buried regions were distributed alternatively. Compared with those of GP1 and sGP, GP2 showed a special structure with a large disorder region on protein surface. The sites 20 ～ 37, 166 ～ 186 at N-terminus of GP1, sites 361 ～ 379 at N-terminus of GP2 as well as sites 20 ～ 37 and 166 ～ 185 at N-terminus of sGP might be transmembrane helical structure. There might be four disulfide bond regions in sGP. B cell epitope analysis showed that the hydrophobic region were mainly concentrated in AA 1 ～ 325 of N-terminus of GP1 and GP2, while the hydrophilic region in AA 326 ～ 676, with a distinct boundary but without obvious overlap. There were two potential linear epitopes at sites 324 ～ 450 and sites 461 ～ 676 at N-terminus respectively. A total of 25 amino acid sites or sequences which might form conformational epitopes were predicted, including 6 with possibilities of more than 90%. Conclusion The prediction of secondary structure and B cell epitope of GP of Ebolavirus strain of type Zaire provided a reference for study on the structure and function of GP, recognition of B cell epitope as well as development of prophylactic, therapy and diagnostic oroducts azainst Ebolavims.