Rzepczyk C M, Csurhes P A, Lord R, Matile H
Queensland Institute of Medical Research, Brisbane, Australia.
J Immunol. 1990 Oct 15;145(8):2691-6.
Peptides representing conserved (MSA2/1A and MSA2/1B) and variant (MSA2/2, MSA2/6 and MSA2/7) regions of the merozoite surface Ag 2 (MSA2) of Plasmodium falciparum (FCQ-27/PNG isolate) were coupled to either peptide NP(NANP)5NA or peptide C(NANP)6 both of which contained the core sequence (NANP)n. The coupling was done via the N-terminus of one peptide and a cysteine residue on either terminus of the other. BL/10 (H-2b) and B10.BR (H-2k) mice were immunized with these MSA2-(NANP)n conjugates. The mice were also immunized with the unconjugated MSA2 peptides and with NP(NANP)5NA and C(NANP)6. Antibody responses were evaluated by 1) ELISA, in which the MSA2 peptides and C(NANP)6 were used as Ag; 2) immunofluorescence assays (IFAT) against intact sporozoites and merozoites; and 3) immunoblotting experiments against solubilized P. falciparum blood stage proteins. High titer antibodies to (NANP)n were elicited in both BL/10 and B10.BR mice after immunization with all the conjugates except MSA2/7-(NANP)n which gave only a very limited response in B10.BR mice. These antibodies recognized unfixed sporozoites. The conjugates also elicited antibodies to MSA2 as shown by ELISA, IFAT, and immunoblotting except for mice immunized with MSA2/1B-(NANP)n where an anti-MSA2 response was only detectable by immunoblotting. Immunization with unconjugated MSA2 peptides showed that MSA2/2 was immunogenic in both BL/10 and BR.10 mice, with MSA2/6 and MSA2/7 being immunogenic only in BL/10 mice. The antibodies elicited recognized both merozoites and the MSA2 protein. However, the antibody titers were lower overall than those seen when these peptides were used in the conjugated form. No anti-MSA2 antibodies were detected after immunization with MSA2/1A and MSA2/1B. Immunization of mice with the peptide NP(NANP)5NA produced antibodies in BL/10 (H-2b) mice only, and the immunogenicity of this preparation was poor. In contrast, C(NANP)6 produced a strong antibody response in both mouse strains. The antibodies elicited by NP(NANP)5NA and C(NANP)6 recognised sporozoites in IFAT. The MSA2 peptides studied (or their derivatives) were previously shown to be recognized by human T cells. Their immunogenic potential shows promise in that complex anti-P. falciparum responses can be elicited with simple synthetic immunogens based on these peptides.
将恶性疟原虫（FCQ - 27/PNG分离株）裂殖子表面抗原2（MSA2）的保守区域（MSA2/1A和MSA2/1B）及变异区域（MSA2/2、MSA2/6和MSA2/7）的肽段与肽NP(NANP)5NA或肽C(NANP)6偶联，这两种肽均含有核心序列(NANP)n。偶联是通过一种肽的N端与另一种肽任一端的半胱氨酸残基进行的。用这些MSA2-(NANP)n偶联物免疫BL/10（H - 2b）和B10.BR（H - 2k）小鼠。还用未偶联的MSA2肽段以及NP(NANP)5NA和C(NANP)6对小鼠进行免疫。通过以下方法评估抗体反应：1）ELISA，其中使用MSA2肽段和C(NANP)6作为抗原；2）针对完整子孢子和裂殖子的免疫荧光测定（IFAT）；3）针对可溶性恶性疟原虫血液期蛋白的免疫印迹实验。用除MSA2/7-(NANP)n之外的所有偶联物免疫后，BL/10和B10.BR小鼠均产生了针对(NANP)n的高滴度抗体，MSA2/7-(NANP)n在B10.BR小鼠中仅产生非常有限的反应。这些抗体可识别未固定的子孢子。ELISA、IFAT和免疫印迹结果表明，除用MSA2/1B-(NANP)n免疫的小鼠外，偶联物还引发了针对MSA2的抗体，在用MSA2/1B-(NANP)n免疫的小鼠中，仅通过免疫印迹可检测到抗MSA2反应。用未偶联的MSA2肽段免疫表明，MSA2/2在BL/10和BR.10小鼠中均具有免疫原性，MSA2/6和MSA2/7仅在BL/10小鼠中具有免疫原性。所引发的抗体可识别裂殖子和MSA2蛋白。然而，总体抗体滴度低于这些肽以偶联形式使用时的滴度。用MSA2/1A和MSA2/1B免疫后未检测到抗MSA2抗体。用肽NP(NANP)5NA免疫小鼠仅在BL/10（H - 2b）小鼠中产生抗体，且该制剂的免疫原性较差。相比之下，C(NANP)6在两种小鼠品系中均产生强烈的抗体反应。NP(NANP)5NA和C(NANP)6所引发的抗体在IFAT中可识别子孢子。先前已表明所研究的MSA2肽段（或其衍生物）可被人T细胞识别。它们的免疫原潜力显示出前景，即基于这些肽的简单合成免疫原可引发复杂的抗恶性疟原虫反应。
