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由两个疟疾疫苗候选抗原AMA 1(III)和MSP1 19融合而成的恶性疟原虫融合抗原 2 (PfCP 2 ) ,是一个很有应用前景的疟疾疫苗候选抗原。但PfCP 2表达产物为双带型 ,这影响到该疫苗候选抗原作为产品进入临床试验。为此分析了表达产物N末端的氨基酸序列 ,发现其中低分子量条带的N末端不完整 ,缺失 9个氨基酸。进一步用PCR技术对PfCP 2进行改建 ,使其N末端缺少 9个氨基酸 ,产生PfCP 2 .9基因。实验结果显示 :PfCP 2 .9在毕赤酵母中的表达产物为单一条带 ,且在表达水平、二硫键依赖的构象、免疫原性及免疫血清抑制疟原虫生长等方面与PfCP 2一致。PfCP 2表达产物双带型问题得到解决 ,为该融合抗原疟疾疫苗进入临床试验排除了重要障碍。
Plasmodium falciparum fusion antigen 2 (PfCP 2), which is a fusion of two malaria vaccine candidate antigens, AMA 1 (III) and MSP 19, is a promising malaria vaccine candidate antigen. However, the PfCP 2 expression product is a double-stranded type, which affects the vaccine candidate antigen entering the clinical trial as a product. For this purpose, the N-terminal amino acid sequence of the expression product was analyzed and found that the N-terminal of the low-molecular-weight band was incomplete and a deletion of 9 amino acids. PfCP 2 was further modified by PCR to delete 9 amino acids at its N-terminus, resulting in the PfCP 2 .9 gene. The experimental results showed that PfCP 2 .9 expressed in Pichia pastoris as a single band and consistent with PfCP 2 in terms of expression level, disulfide bond-dependent conformation, immunogenicity and immune serum inhibition of Plasmodium growth. The problem of double-banding of the PfCP 2 expression product was solved and the major obstacle was eliminated for the clinical trial of the fusion antigen malaria vaccine.