Seattle Biomedical Research Institute, 307 Westlake Ave N, Suite 500, Seattle Washington, 98109-5219, USA.
Malar J. 2011 Feb 11;10:36. doi: 10.1186/1475-2875-10-36.
Pregnancy associated malaria is a severe clinical syndrome associated with sequestration of Plasmodium falciparum-infected erythrocytes in the placenta. Placental binding is mediated by VAR2CSA, which adheres to chondroitin sulphate A (CSA). VAR2CSA is a large and polymorphic protein that has six Duffy binding-like (DBL) domains. There is still limited understanding as to how effective individual VAR2CSA domains are at generating inhibitory antibodies or the number of domain variants needed for universal vaccine coverage.
To investigate the immunogenic properties of single domain VAR2CSA recombinant proteins, rats or rabbits were immunized with five of the six VAR2CSA domains produced in Pichia pastoris. Immune plasma was analysed against a geographically diverse panel of CSA-binding lab lines to assess antibody breadth and inhibitory activity.
Of the five domains, DBL3, and to a lesser extent DBL5, induced antibodies that cross-reacted on five diverse CSA-binding parasite lines by flow cytometry. By comparison, anti-DBL6 antibodies were highly strain-specific and anti-DBL1 and anti-DBL4 antibodies were poorly reactive by flow cytometry. From this series of recombinant proteins, adhesion-blocking activity was restricted to a single rat immunized against a DBL4 recombinant protein.
Single domain VAR2CSA recombinant proteins produced in P. pastoris had limited efficacy in eliciting adhesion blocking antibody responses, but VAR2CSA DBL3 and DBL5 domains contain strain-transcendent epitopes that can be targeted by vaccination and may have application for vaccine development.
妊娠相关疟疾是一种严重的临床综合征，与疟原虫感染的红细胞在胎盘内的隔离有关。胎盘结合由 VAR2CSA 介导，该蛋白与硫酸软骨素 A（CSA）结合。VAR2CSA 是一种大型多态性蛋白，具有六个 Duffy 结合样（DBL）结构域。目前对于单个 VAR2CSA 结构域在产生抑制性抗体方面的有效性以及产生通用疫苗覆盖所需的结构域变体数量仍知之甚少。
为了研究单个结构域 VAR2CSA 重组蛋白的免疫原性，用毕赤酵母表达的六个 VAR2CSA 结构域中的五个结构域对大鼠或兔进行免疫。用免疫血浆分析与地理上多样化的 CSA 结合实验室系进行交叉反应，以评估抗体的广度和抑制活性。
在这五个结构域中，DBL3 结构域，在较小程度上是 DBL5 结构域，通过流式细胞术诱导交叉反应五种不同 CSA 结合寄生虫系的抗体。相比之下，抗 DBL6 抗体高度特异性，抗 DBL1 和抗 DBL4 抗体通过流式细胞术反应性差。从这一系列重组蛋白中，只有针对 DBL4 重组蛋白免疫的大鼠产生的黏附阻断活性。
毕赤酵母表达的单个结构域 VAR2CSA 重组蛋白在诱导黏附阻断抗体反应方面效果有限，但 VAR2CSA DBL3 和 DBL5 结构域含有跨株的表位，可作为疫苗接种的靶点，可能对疫苗开发有应用价值。
