N端9个氨基酸缺失对恶性疟融合抗原免疫原性的影响

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。

Influence of Deleting 9 Amino Acid Residues at N-Terminus on Immunogenicity of a Plasmodium falciparum Chimeric Protein

Plasmodium falciparum chimeric protein 2 (PfCP-2), fused by erythrocytic stage antigens, AMA-1(III) and MSP1-19, is a potential vaccine candidate against malaria. However, the two-band pattern of this protein product in SDS-PAGE has some negative influence for the application of it for clinical tests. N-terminal sequence analysis of the product showed that the doublet had different N-terminus, with 9 amino acid deletion in the band with low molecular weight. Therefore, the gene was modified to generate a new construct, named PfCP-2.9, which was lack of these 9 residues at its N-terminus. Expression of PfCP- 2.9 produced only one band. Moreover, the new construct was as same as the origined product in the level of expression, conformation dependence on the disulfide bond, immunogenicity and inhibitory effect on the parasite growth in vitro.