摘要
首次采用基因融合方式，在乱毒素B亚基-乙型肝炎病毒Pres2抗原融合基因（ctxB-Pres2）的5’端了引入编码大肠杆菌脂蛋白信号肽及N端九个氨基酸的核苷酸序列，分别置于ctb及lpp／lac启动子下在大肠杆菌中获得分泌性表达．表达的融合蛋白均定位于膜上，并且可以和GM1、抗-CTB抗体及抗HBVPreS2单克隆抗体结合，说明该融合蛋白保留了CTB的基本高级结构及CTB、PreS2抗原的抗原性．3H-棕榈酸标记实验证实该融合蛋白发生脂肪化，为免疫原性研究奠定了基础．此外，还研究了不同信号肽和宿主菌对该蛋白表达的影响．
Lipoprotein(lpp)of the outer membrane of E. coli is a major protein of the cell wall.N-terminal amino acids of lipoprotein and its artifical analogues were promising adjuvant in construction of peptide vaccine for their activity activating B-lymphocyte,macrophage and CTL. Nucleotides encoding signal peptide and N-terminal nine amino acids(LPP9)of lipoprotein were genetically fused to 5'end of ctxB-Pres2 gene by means of PCR. The fusion protein was well expressed with relatively low yield (about 0.1-0. 2mg/l),and anchored in cell membrane. The fusion protein obtained in this way was more convenient and economical than chemical conjugation.The chimera was modified correctly and retained the biological activity of both CTB and Pres2 as confirmed by 3H-palmitic acid labelling test and GM I Enzyme Linked lmmunosorbent Assay respectively. It was also demonstrated that the signal peptide of lipoprotein was important to the correct modification of the chimera,and ctxB promoter was more efficient than that of lpp on the expression of chimera. Studies on the immunogenicity of the chimera are now in progress.
