Departamento de Biologia, Universidade Estadual Paulista Júlio Mesquita Filho, São José do Rio Preto, São Paulo State, Brazil.
Malar J. 2010 Jun 23;9:178. doi: 10.1186/1475-2875-9-178.
Plasmodium vivax circumsporozoite variants have been identified in several geographical areas. The real implication of the genetic variation in this region of the P. vivax genome has been questioned for a long time. Although previous studies have observed significant association between VK210 and the Duffy blood group, we present here that evidences of this variation are limited to the CSP central portion.
The phylogenetic analyses were accomplished starting from the amplification of conserved domains of 18 SSU RNAr and Cyt B. The antibodies responses against the CSP peptides, MSP-1, AMA-1 and DBP were detected by ELISA, in plasma samples of individuals infected with two P. vivax CS genotypes: VK210 and P. vivax-like.
These analyses of the two markers demonstrate high similarity among the P. vivax CS genotypes and surprisingly showed diversity equal to zero between VK210 and P. vivax-like, positioning these CS genotypes in the same clade. A high frequency IgG antibody against the N- and C-terminal regions of the P. vivax CSP was found as compared to the immune response to the R- and V- repetitive regions (p = 0.0005, Fisher's Exact test). This difference was more pronounced when the P. vivax-like variant was present in the infection (p = 0.003, Fisher's Exact test). A high frequency of antibody response against MSP-1 and AMA-1 peptides was observed for all P. vivax CS genotypes in comparison to the same frequency for DBP.
This results target that the differences among the P. vivax CS variants are restrict to the central repeated region of the protein, mostly nucleotide variation with important serological consequences.
已在多个地理区域鉴定出间日疟原虫环子孢子蛋白变体。该疟原虫基因组这一区域的遗传变异的实际意义长期以来一直受到质疑。尽管先前的研究观察到 VK210 与达菲血型之间存在显著关联，但我们在此提出，这种变异的证据仅限于 CSP 的中央部分。
从 18S SSU RNA 和 Cyt B 的保守结构域扩增开始进行系统发育分析。通过 ELISA 检测感染两种间日疟原虫 CS 基因型（VK210 和类间日疟原虫）的个体血浆样本中针对 CSP 肽、MSP-1、AMA-1 和 DBP 的抗体反应。
这两个标记物的分析表明 CS 基因型之间具有高度相似性，令人惊讶的是，VK210 和类间日疟原虫之间的多样性为零，将这些 CS 基因型定位在同一进化枝中。与针对 CSP 的 R-和 V-重复区的免疫反应相比，发现针对 P. vivax CSP 的 N-和 C-末端区域的 IgG 抗体的高频（p = 0.0005，Fisher 精确检验）。当感染中存在类间日疟原虫变体时，这种差异更为明显（p = 0.003，Fisher 精确检验）。与 DBP 相比，所有 P. vivax CS 基因型对 MSP-1 和 AMA-1 肽的抗体反应频率都较高。
这些结果表明，间日疟原虫 CS 变体之间的差异仅限于该蛋白的中央重复区，主要是核苷酸变异，具有重要的血清学后果。
