摘要目的 分析EB病毒(EBV)潜伏膜蛋白2(LMP2)B淋巴细胞表位的免疫原性.方法 利用生物信息学技术筛选出EBV LMP2可能的优势B淋巴细胞表位LMP2199-209、LMP2318-322和LMP2381-391,将其相应基因片段分别克隆至pET32a(+)载体并转化至大肠埃希菌BL21(DE3)菌株诱导表达,表达产物经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)和蛋白免疫印迹分析鉴定,通过Ni-NTA离子螯合亲和层析柱纯化.分别以纯化的表位蛋白作为免疫原,皮下多点注射BALB/c小鼠,设pET32a(+)蛋白和PBS为对照.分别以3个表位蛋白作包被抗原,ELISA法检测第0、3、6周小鼠血清中相应表位特异性抗体IgG,并于免疫后第6周检测各免疫组小鼠血清抗体识别天然EBV抗原的能力.结果 在原核表达体系中分别获得了表位LMP2199-209、LMP2318-322和LMP2381 391融合表达产物.纯化的表位蛋白免疫小鼠,血清中分别能检测到相应的表位特异性抗体IgG,其抗体水平随着免疫次数的增加而呈现逐渐升高的趋势,表位LMP2318-322免疫组第3、6周小鼠血清抗体显著高于pET32a(+)蛋白对照组(F=493.85、773.99,均P＜0.05),LMP2381 391免疫组第3、6周抗体水平亦显著高于pET32a(+)蛋白对照组(F=926.33、309.14,均P＜0.05),而表位LMP2199 209免疫组至第6周特异性抗体高于pET32a(+)蛋白对照组(F=87.27,P＜0.05).3个表位蛋白免疫小鼠血清抗体IgG均能识别EBV天然抗原,以表位LMP2199-209和LMP2381-391免疫组抗EBV-IgG生成水平尤为显著.结论 筛选的EBV LMP2可能的优势B淋巴细胞表位LMP2199-209、LMP2318-322和LMP2381-391通过原核表达体系中制备的表位蛋白,具有较好的免疫原性,可进一步用于EBV感染及其相关肿瘤表位疫苗的研究.

abstractsObjective To analyze the immunogenicity of selected B-cell epitopes of Epstein-Barr virus (EBV) latent membrane protein-2 (LMP2). Methods Three potential dominant B-cell epitopes of LMP2199-209, LMP2318-322 and LMP2381-391 from EBV LMP2 had been predicted using bioinformaties methods. The gene fragments of three epitopes were cloned respectively into pET32a(+) vector and transformed into E. coli strain BL21 (DE3). After identification by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting, the expression products were purified by Ni-NTA agarose affinity chromatography. BALB/c mice in immunized groups were immunized by multi-point intracutaneous injection with the three purified epitope proteins,respectively; and mice in control groups were injected with pET32a (+) protein or phosphate buffered saline(PBS), respectively. The sera from mice at week O, week 3 and week 6 of injection were collected for determination of epitope-specific antibody IgG by enzyme linked immunosorbent assay (ELISA) using epitope proteins as coating antigens. The ability of serum antibody recognizing nature EBV antigen was determined at week 6 of immunization. Results Three epitope proteins of LMP2199-209 ,LMP2318-322 and LMP2381-391 were successfully expressed in prokaryotic system. Epitopespecific antibodies IgG could be detected respectively in the sera of all immunized mice, and the levels of antibodies increased with immunized time increasing. The antibody levels in LMP2318-322 immunized group at week 3 and week 6 were significantly higher than that of pET32a (+) protein control group (F= 493.85 and 773.99, respectively; both P＜0. 05), and the antibody levels in LMP2381-391 immunized group at week 3 and week 6 were also significantly higher than that of pET32a (+) protein control group (F= 926.33 and 309.14, respectively; both P＜0.05). Antibody level in LMP2199-209 immunized group at week 6 was significantly higher than that of pET32a ( + ) protein control group (F=87.27, P＜0.05). The antibody IgG in serum from immunized mice with three epitope proteins could all recognize nature EBV antigens, especially LMP2199-209 and LMP2381-391 immunized groups.Conclusions Three possible dominant epitopes of LMP2199-209, LMP2318-322 and LMP2381-391 from EBV LMP2 are prepared by prokaryotic expression system and exhibit obvious immunogenicity, which could be used for further research of EBV infection and related tumor vaccine.