A carboxyl-terminal fragment of Plasmodium falciparum gp195 expressed by a recombinant baculovirus induces antibodies that completely inhibit parasite growth.
A carboxyl-terminal fragment of Plasmodium falciparum gp195 expressed by a recombinant baculovirus induces antibodies that completely inhibit parasite growth.
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DOI：
10.4049/jimmunol.149.2.548
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发表时间：
1992-07
影响因子：
4.4
通讯作者：
Sandra P. Chang;H. Gibson;C. T. Lee-Ng;Philip J. Barr;George Hui
中科院分区：
文献类型：
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作者：
Sandra P. Chang;H. Gibson;C. T. Lee-Ng;Philip J. Barr;George Hui
恶性疟原虫的主要裂殖子表面Ag（gp195）已被证明可以保护猴子免受寄生虫感染，并且基于gp195的合成肽和重组多肽已被评估为潜在的疟疾疫苗。开发基于gp195的重组疫苗的一个主要问题是难以获得在免疫学上与天然蛋白等效的重组多肽。在本研究中，gp195 的羧基末端加工片段 (p42) 在酵母和杆状病毒重组系统中产生。免疫学分析表明，分泌的杆状病毒 p42 (BVp42) 表达天然的二硫键依赖性构象表位，而这些表位在细胞内酵母 p42 中表现不佳。 BVp42（而非酵母 p42）也被纯化的天然 gp195 免疫动物的大多数 gp195 特异性抗体识别，表明这些动物的抗 gp195 反应集中在 p42 加工片段的构象决定簇上。不同 H-2 单倍型同源小鼠的天然 gp195 血清可识别 BVp42 多肽，表明遗传异质群体能够对 p42 表位做出反应。 BVp42 具有高度免疫原性，并诱导产生高滴度的抗体，这些抗体在 ELISA 中与纯化的天然 gp195 发生交叉反应，并且通过免疫荧光也与裂殖体和裂殖子发生反应。抗BVp42抗体完全抑制疟疾寄生虫的体外生长，而抗酵母p42抗体则没有效果。这些结果表明p42的天然构象表位对于诱导gp195特异性寄生虫生长抑制抗体至关重要，并且BVp42多肽有效地诱导对这些天然决定簇具有特异性的抗体。
The major merozoite surface Ag (gp195) of Plasmodium falciparum has been shown to protect monkeys against parasite infection, and gp195-based synthetic peptides and recombinant polypeptides have been evaluated as potential malaria vaccines. A major problem in developing a gp195-based recombinant vaccine has been the difficulty in obtaining a recombinant polypeptide that is immunologically equivalent to the native protein. In this study, the carboxyl-terminal processing fragment (p42) of gp195 was produced in yeast and in a baculovirus recombinant system. Immunologic analyses indicated that the secreted baculovirus p42 (BVp42) expressed native, disulfide-dependent conformational epitopes, whereas these epitopes were poorly represented in the intracellular yeast p42. BVp42, but not yeast p42, was also recognized by the majority of gp195-specific antibodies of animals immunized with purified native gp195, indicating that the anti-gp195 response of these animals was focused on conformational determinants of the p42 processing fragment. Sera against native gp195 of congenic mice of diverse H-2 haplotypes recognized the BVp42 polypeptide, demonstrating that a genetically heterogeneous population is capable of responding to p42 epitopes. BVp42 was highly immunogenic and induced high titers of antibodies that were cross-reactive with purified native gp195 in an ELISA and also reacted with schizonts and merozoites by immunofluorescence. Anti-BVp42 antibodies completely inhibited the in vitro growth of the malaria parasite, whereas anti-yeast p42 antibodies had no effect. These results indicate that native, conformational epitopes of p42 are critical for the induction of gp195-specific, parasite growth-inhibitory antibodies and that the BVp42 polypeptide efficiently induces antibodies specific for these native determinants.