猪圆环病毒2型Cap蛋白B细胞表位的预测及鉴定

Prediction and Identification of B Cell Epitopes of the PCV2 Cap Protein

利用生物信息学技术和原核表达系统,筛选猪圆环病毒2型(PCV2)核衣壳蛋白(Cap)的B细胞表位,为进一步揭示PCV2的免疫调控机制提供研究依据.运用生物信息学软件预测PCV2 Cap蛋白的亲水性、表面可及性、蛋白柔韧性、抗原性和B细胞线性表位;根据预测结果,初步确定Cap蛋白潜在的B细胞线性表位主要位于58~66、79~91、151~162、174~189、204~213和221~233位氨基酸.设计特异性引物,扩增Cap蛋白潜在表位区域基因,并克隆到p ET32a(+)原核表达载体上,转化至表达菌BL21(DE3)plys S中,在IPTG诱导下表达目的蛋白;利用PCV2阳性血清鉴定Cap蛋白的B细胞线性表位,筛选出3个能与血清结合的肽段,即Cap77-95、Cap174-189和Cap221-233;对获得的肽段进行在线同源比对,发现3个片段均为PCV2 Cap蛋白的特有序列,有可能成为PCV2的特异性表位.

Screening B cell epitopes of PCV2 Cap by bioinformatics techniques and prokaryotic expression systems,could provide a basis to further reveal the immune regulation mechanism of PCV2. The hydrophilicity,flexibility,accessibility,antigenicity and B-cell liner epitopes of PCV2 Cap were predicted by bioinformatics methods. There were 6 potential B-cell linear epitopes in Cap. They might locate in the regions of 58-66,79-91,151-162,174-189,204-213 and 221-233 aa. The potential epitopes gene were amplified by PCR using specific primers and cloned into the expression vector p ET32a（ ＋）. E coli BL21（ DE3） plys S cells were transformed with the recombinant plasmid; and the target proteins were expressed by induction using IPTG; B-cell linear epitopes of Cap protein were identified by detecting the reactivity of the target proteins with PCV2 positive serum. Three kinds of protein peptides（ Cap77-95,Cap174-189,Cap221-233） with reactogenicity were selected. Analysis of homology indicated that three segments were unique to Cap which might be the specific epitopes of PCV2.