Molecular mechanism of malaria pathogenesis

总结：鉴于在疟疾抗药性和病媒控制方面出现的困难，以及持续缺乏有效疫苗，需要制定新的疟疾疫苗开发战略。 我们使用了一种新的方法来合成和充分表征多个抗原肽缀合物（MAP）含有保护性表位恶性疟原虫，并评估其免疫原性在四个不同品系的小鼠。本研究测试了含有肝期抗原-1（LSA-1）的两个T细胞表位的双表位MAP（T3-T1）、含有来自LSA-1和裂殖子表面蛋白-1（MSP-1）的T细胞表位的双表位MAP以及含有T3-T1和来自环子孢子蛋白（CSP）中央重复区的有效B细胞表位的三表位MAP（T3-CS-T1）。 所有四种品系的小鼠均产生肽特异性抗体，然而体液应答的幅度显示不同品系小鼠之间存在显著的遗传变异。 抗MAP抗体在免疫荧光试验（IFA）中识别疟原虫上的阶段特异性蛋白。此外，用MAPT 3-CS-T1三表位免疫的BALB/cJxA/JCAF 1杂交小鼠的血清在体外成功地抑制了疟原虫子孢子对肝癌细胞的侵袭。 来自免疫小鼠的脾细胞在体外用免疫原刺激时也显示出遗传限制的细胞免疫应答。 这项研究表明，结合固相合成和缀合化学的良好表征的MAP是有效的免疫原，并且这种方法可以用于亚单位疫苗的开发。

Summary: Given the emerging difficulties with malaria drug resistance and vector control, as well as the persistent lack of an effective vaccine, new malaria vaccine development strategies are needed. We used a novel methodology to synthesize and fully characterize multiple antigen peptide conjugates (MAPs) containing protective epitopes from Plasmodium falciparum and evaluated their immunogenicity in four different strains of mice. A di-epitope MAP (T3-T1) containing two T-cell epitopes of liver stage antigen-1 (LSA-1), a di-epitope MAP containing T-cell epitopes from LSA-1 and from merozoite surface protein-1 (MSP-1), and a tri-epitope MAP (T3-CS-T1) containing T3-T1 and a potent B-cell epitope from the circumsporozoite protein (CSP) central repeat region were tested in this study. Mice of all four strains produced peptide specific antibodies, however the magnitude of the humoral response showed marked genetic variation between the different strains of mice. Anti-MAP antibodies recognized stage-specific proteins on the malaria parasites in an immunofluoresence assay (IFA). In addition, serum from hybrid BALB/cJ x A/J CAF1 mice that had been immunized with the tri-epitope MAP T3-CS-T1 successfully inhibited the malaria sporozoite invasion of hepatoma cells in vitro. Spleen cells from immunized mice also showed a genetically restricted cellular immune response when stimulated with the immunogen in vitro. This study indicates that well-characterized MAPs combining solid phase synthesis and conjugation chemistries are potent immunogens and that this approach can be utilized for the development of subunit vaccines.