肠道病毒71型VP1基因的扩增、克隆、表达及蛋白分析

Amplification,cloning,expression and protein analysis of enterovirus 71 VP1 gene

目的对肠道病毒71型VP1基因片段进行扩增、克隆、生物信息学分析、原核表达、纯化,初步证实重组表达产物的生物学活性。方法根据GenBank中EV71序列设计一对特异性引物,以EV71患者咽拭子标本中提取病毒核糖核酸为模板,RT-PCR扩增EV71 VP1基因,酶切后插入表达载体pET28a。构建pET28a-EV71 VP1原核表达载体。转化E.coli DH5α,IPTG诱导表达,使用SDS-PAGE及Western blot分析表达结果,利用软件对测序结果进行生物信息学分析。纯化蛋白并包被反应板,用ELISA分别检测EV71阳性与COX A16阳性患者VP-1IgG抗体,进行统计学分析。结果目的基因经BLAST比对,同源性与GenBank登录号为JQ766207.1 EV71 VP1一致性达99%。EV71 VP1蛋白相对分子质量约为32×103,主要以包涵体形式存在。生物信息学分析得出,EV71 VP1蛋白为亲水性蛋白,无跨膜区,不具有N-端信号肽序列,存在三级结构。ELISA结果显示EV71阳性患者OD值为(2.425±0.521),COX A16阳性患者OD值为(1.205±0.314),健康对照组OD值为(0.353±0.128)。EV71 VP1蛋白检测敏感性和特异性分别为84%和88%。结论成功构建了pET28a-EV71 VP1表达载体;通过对手足口患者血清进行ELISA初步分析,得出目的蛋白有较高的敏感性和特异性,初步证实具有生物学活性,可进一步用于EV71诊断及疫苗的相关研究。

Objective To conduct the amplification,cloning,bioinformatics analysis,prokaryotic expression and purification of enterovirus 71 VP1 gene segment and to initially confirm the biological activity of the recombinant expression product.Methods A pair of specific primers was designed according to GenBank EV71 sequence,viral RNA as a template was extracted from the throat swab specimens in the EV71 patients.EV71 VP1 gene was amplified by RT-PCR.After enzyme digestion,the expression vector pET28a was inserted.The prokaryotic expression vector of pET28a-EV71 VP1 was constructed.Then the E.coli DH5a transforma-tion was performed.IPTG was adopted for induction expression.The expression results were analyzed by using SDS-PAGE and Western blot.The bioinformatics analysis of the sequenced results was performed by the software.Expressed protein was purified and the plates were coated,ELISA was used to test the VP1 specific IgG antibody in serum samples of EV71 positive and COX A16-positive patients.Results The BLAST alignment showed that the homology of the objective gene EV71 VP1 was 99% com-pared with other strains（JQ766207.1）in GenBank.EV71 VP1 protein was about 32×10^3 ,which mainly existed in the form of in-clusion body.The bioinformatics analysis showed that EV71 VP1 protein was a hydrophilic protein,without transmembrane region and N-terminal signal peptide sequence,the tertiary structure existed.The ELISA results showed that the specific IgG OD value in EV71-positive patients was（2.425±0.521）,OD value in COX A16 positive patients was（1.205±0.314）,the normal control OD value was（0.353±0.128）.The sensitivity and specificity of EV71 VP1 protein detection were 84% and 88% respectively.Conclu-sion The pET28a-EV71 VP1 expression vector is successfully constructed;the preliminary analysis on the serum of the infected patients by ELISA shows that the obtained objective protein has higher sensitivity and specificity,which is initially confirmed to have biological activity and can be further used for the related study on EV71 diagnosis and vaccine.