人乳头瘤病毒L2氨基端蛋白的同源性及其交叉反应特性研究

目的 研究人乳头瘤病毒(HPV)次要衣壳蛋白(L2)在临床常见HPV感染型别中的同源性及其交叉反应特性.方法 采用生物信息学方法对临床常见HPV感染型别中的L2氨基酸序列进行比对,发现其氨基端1～200序列具有高度同源性.采用PCR法从宫颈癌患者组织DNA中扩增HPV16 L2(1～200)肽段的碱基序列,将其克隆至原核表达载体PGEX-4T-1得到重组质粒PGEX-4T-1-HPV16 L2(1～200).将测序鉴定正确的重组质粒转入E.coli BL21(DF3)中,经异丙基-β-D-硫代半乳糖苷(IPTG)诱导表达,SDS-PAGE和Western blot鉴定;进一步通过Western blot检测HPV16L2(1～200)融合蛋白与HPV6、11、16和18型DNA检测阳性临床患者血清的特异性结合能力;以镍螯合亲和层析柱(Ni-NTA Agarose)纯化的HPV16 L2(1～200)融合蛋白作为包被抗原,采用间接ELISA法对98例尖锐湿疣患者、135例宫颈癌患者及96例健康对照者血清进行特异性血清IgG抗体检测.结果 在HPV6、11、18、35等14个临床常见型别中,与HPV16 L2的1～200间的氨基酸序列比较,同源性达到52.7%～74.3%;成功构建了含有HPV16 L2(1～200)的重组质粒PGEX-4T-1-HPV16 L2(1～200),含有HPV16 L2(1～200)的融合蛋白在原核表达体系中呈高效表达,表达量占总蛋白的22.6%;表达产物的相对分子质量(Mr)约49×103,与预期Mr相符;以HPV6、11、16和18 DNA阳性患者血清为一抗进行Western blot分析,结果显示,在Mr约49×103处出现特异性条带.ELISA结果显示,尖锐湿疣组、宫颈癌组患者血清及健康对照者血清抗体均值分别为0.753±0.262、0.756±0.274和0.178±0.157,阳性率分别为89.8%、88.9%和9.4%.三组间血清抗体均值及阳性率比较差异均具有统计学意义(P均＜0.001),而尖锐湿疣组和宫颈癌组间的血清抗体均值比较差异无统计学意义(P＞0.05).结论 HPV L2 N端1～200氨基酸序列具有高度同源性,并在HPV6、11、16和18型别间具有交叉反应.

Research on homology and cross reaction characteristics of human papillomavirus L2 N-terminal protein

Objective To research the homology and cross reaction characteristics of human papillomavirus(HPV)16 type L2 N-terminal(1-200)protein in clinical common HPV infection types.Methods The amino acid sequences of the common HPV infection types(6,11,16,18 ,etc.)were blasted and it was found that 1-200 N-terminal sequence of L2 protein was highly homologous.The gene of HPV16 L2(1-200)was amplificated from tissue sample of cervical cancer patient and inserted into the prokaryotic expression vector PGEX-4T-1 to construct the recombinant plasmid PGEX-4T-1-HPV16 L2(1-200).After sequencing identification,the recombinant plasmid was tranformed into E.coli BL21(DE3).Induced by IPTG,the fusion protein containing HPV16 L2(1-200)was expressed and analyzed by both SDS-PAGE and Western blot.Furthermore,the specific binding capacity of the fusion protein to the HPV 6,11,16 and 18 DNA positive patient serums were analyzed by Western blot.The fusion protein was purified with Ni-NTA Agarose Kit and coated with ELISA reaction plates.The specific serum IgG of 98 condyloma acuminatum patients,135 cervix cancer patients and 96 healthy control subjects were detected respectively by indirect ELISA.Results After comparing the amino acid sequences of the common HPV infection types(HPV6,11,16,18,etc.),We found that the homology of HPV L2(1-200)reached 52.7%-74.3%.The recombinant plasmid PGEX-4T-1-HPV 16 L2(1-200)was constructed successfully.Highly expressed HPV16 L2(1-200)fusion protein was obtained and the expression level was account for up to about 22.6% of total bacterial protein.The relative molecular mass(Mr)of the fusion protein is about 49×103,which matches up to the expected Mr Meanwhile,the serums of HPV 6,11,16,18 DNA positive patients were used as the first antibody and the specific band was detected respectively at about 49 × 103 by Western blot.Indirect ELISA showed that the A490 values of the specific IgG of condyloma acuminatum group,cervical cancer group and healthy control subjects were 0.753 ± 0.262,0.756 ± 0.274 and 0.178 ± 0.157 with the positive rate were 89.8%,88.9% and 9.4% respectively.There was no significance of the specific IgG between condyloma acuminatum group and cervical cancer group(P＞0.05),but it was significant among the three groups(P＜0.001).Conclusion The N-terminal 1-200 amino acids of HPV L2 has high homology and there exits cross reaction among the most common HPV infection types.