Laboratory of Immunoparasitology, Institute Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil.
Vaccine. 2011 Feb 17;29(9):1801-11. doi: 10.1016/j.vaccine.2010.12.099. Epub 2011 Jan 6.
The Plasmodium vivax Merozoite Surface Protein-3α (PvMSP-3α) is considered as a potential vaccine candidate. However, the detailed investigations of the type of immune responses induced in naturally exposed populations are necessary. Therefore, we aim to characterize the naturally induced antibody to PvMSP-3α in 282 individuals with different levels of exposure to malaria infections residents in Brazilian Amazon. PvMSP3 specific antibodies (IgA, IgG and IgG subclass) to five recombinant proteins and the epitope mapping by Spot-synthesis technique to full-protein sequence of amino acids (15aa sequence with overlapping sequence of 9aa) were performed. Our results indicates that PvMSP3 is highly immunogenic in naturally exposed populations, where 78% of studied individuals present IgG immune response against the full-length recombinant protein (PVMSP3-FL) and IgG subclass profile was similar to all five recombinant proteins studied with a high predominance of IgG1 and IgG3. We also observe that IgG and subclass levels against PvMSP3 are associated with malaria exposure. The PvMSP3 epitope mapping by Spot-synthesis shows a natural recognition of at least 15 antigenic determinants, located mainly in the two blocks of repeats, confirming the high immunogenicity of this region. In conclusion, PvMSP-3α is immunogenic in naturally exposed individuals to malaria infections and that antibodies to PvMSP3 are induced to several B cell epitopes. The presence of PvMSP3 cytophilic antibodies (IgG1 and IgG3), suggests that this mechanism could also occur in P. vivax.
疟原虫 vivax 裂殖子表面蛋白-3α（PvMSP-3α）被认为是一种有潜力的疫苗候选物。然而，有必要对自然暴露人群中诱导的免疫反应类型进行详细研究。因此，我们旨在对 282 名居住在巴西亚马逊地区的疟疾感染自然暴露人群中对 PvMSP-3α 产生的自然诱导抗体进行特征分析。对五种重组蛋白的 PvMSP3 特异性抗体（IgA、IgG 和 IgG 亚类）和通过斑点合成技术对全长氨基酸序列（15aa 序列重叠 9aa）的表位作图进行了研究。结果表明，PvMSP3 在自然暴露人群中具有高度免疫原性，78%的研究个体对全长重组蛋白（PVMSP3-FL）产生 IgG 免疫反应，且 IgG 亚类谱与所研究的所有五种重组蛋白相似，以 IgG1 和 IgG3 的高优势为主。我们还观察到，针对 PvMSP3 的 IgG 和亚类水平与疟疾暴露相关。斑点合成的 PvMSP3 表位作图显示，至少有 15 个抗原决定簇被自然识别，这些决定簇主要位于重复区的两个块中，证实了该区域的高免疫原性。总之，PvMSP-3α 在自然暴露于疟疾感染的个体中具有免疫原性，针对 PvMSP3 的抗体可诱导出多个 B 细胞表位。PvMSP3 细胞亲嗜性抗体（IgG1 和 IgG3）的存在表明，这种机制也可能发生在 P. vivax 中。
