恶性疟原虫裂殖子表面主要蛋白对裂殖子入侵人红细胞的抑制作用

恶性疟原虫裂殖子表面主要蛋白－１（ＭＳＡ１），又称Ｐ１９５，与人红细胞具有结合作用，这种结合是裂殖子识别红细胞的基础。为了确定Ｐ１９５蛋白与识别有关的位点，本研究在大肠杆菌中分８段表达了ＭＡＤ２０株恶性疟原虫的Ｐ１９５蛋白。各段蛋白用镍亲和层析柱分离，然后复性。在体外培养疟原虫至成熟裂殖体期，将各段蛋白分别加入到培养基上清中，继续培养２４小时，检查红细胞感染率，通过感染率了解各段蛋白对裂殖子入侵红细胞的影响。结果发现Ｐ１９５蛋白中氨基酸序列为３８４－５９５的一段蛋白（Ｍ６），呈剂量依赖性抑制恶性疟原虫裂殖子入侵人红细胞，且Ｍ６对疟原虫生长无细胞毒性作用。这表明Ｍ６可能含红细胞结合位点，该位点与裂殖子竞争性结合红细胞，而使感染率下降

INHIBITING EFFECTS OF MAJOR MEROZOITE SURFACE ANTIGEN 1 OF PLASMODIUM FALCIPARUM ON INVASION OF MEROZOITE INTO HUMAN ERYTHROCYTES

Major merozoite surface antigen 1(MSA1)of Plasmodium falciparum, P195,has the ability to bind to human erythrocytes. This binding is the base of recognition of merozoite of Plasmodium falciparum to human erythrocytes. In order to map out the binding site of P195 to human erythrocytes, we expressed P195 protein in E.coli in eight subunits. The expressed proteins were purified by Ni NTA resin. After being refolded, the eight P195 proteins were added into culture medium of Plasmodium falciparum in vitro respectively. The results showed that a fragment of P195,with amino acid sequence from 384 595,had the ability to inhibit the invasion of Plasmodium falciarum merozoite into human erythrocytes. The results also showed that the effect of inhibition was not caused by toxic effect of the fragment on parasite.