人类肝素酶B细胞表位的预测和免疫原性鉴定

目的 预测并鉴定肝素酶(heparanase)蛋白B细胞表位免疫原性.方法 以肝素酶蛋白的氨基酸序列为基础,采用DNAStar分析软件以及Bcepred在线二级结构分析工具分析其蛋白二级结构并预测B细胞表位.根据预测结果 ,采用8分支多抗原肽结构合成针对该表位的抗原肽,将后者与通用型T辅助表位人IL-1β线性短肽(VQGEESNDK,氨基酸163～171)联合免疫日本白毛黑眼兔,检测免疫血清效价,鉴定其特异性和免疫原性.结果 软件预测显示,肝素酶蛋白大亚基的第1～15位(MAP1)、第279～293位(MAP2)及175～189位(MAP3)氨基酸序列最可能为其优势B细胞表位.间接酶联免疫吸附试验、免疫印迹及免疫组化分析,证实MAP1、MAP2及MAP3均能诱导机体产生高滴度抗体,但仅MAP1、MAP2抗体具有高特异性,MAP2抗体与肝癌组织的结合力最强.结论 肝素酶大亚基的第1～15位、第279～293位氨基酸为其优势B细胞表位,其中第279～293位氨基酸的免疫原性最强,这为肝素酶多肽抗体及B细胞优势短肽疫苗研制提供了理论依据.

Prediction of the B cell epitopes of human heparanase protein and determination of their immunogenicity

Objective To predict the secondary structure and the B cell epitopes of human heparanase protein, and to identify its immunogenicity. Methods The flexible regions of secondary structure and the B cell epitopes of human heparanase amino acid sequence were predicted by DNAStar and Bcepred software. The multiple antigenic peptides (MAP) of the epitopes were synthesized in 8-branch form. Rabbits were immunized with the 8-branch MAPs mixed with a universal T-helper epitope human IL-1β peptide (VQGEESNDK, amino acid 163-171 ). The immunogenicity of the synthesized peptides was evaluated by ELISA, Western blot and immunohistochemistry. Results Amino acid 1 -15 ( MAP1), 279-293 (MAP2) and 175-189(MAP3) of large-subunit of human heparanase protein was predicted as the most potential epitopes of human heparanase protein. All the three synthesized MAPs induced high titer of antibodies. ELISA, Western blot and immunohistochemistry analysis showed all the three MAPs could produce high titer serum antibodies, antibodies induced by MAP1 and MAP2 had high specific binding activity , and MAP2 antibody showed the strongest binding activity with liver cancer tissues. Conclusion The large-subunit No. 1-15, 279-293 amino acid of human heparanase protein may be the B cell preponderant epitopes and the strongest immunogenicity may be No. 279-293 peptide, which provided a theoretic basis for the antibody and vaccine development of heparanase subunit peptide.