Department of International Health, Immunology, and Microbiology, University of Copenhagen, Copenhagen, Denmark.
Malar J. 2010 May 28;9:147. doi: 10.1186/1475-2875-9-147.
The Plasmodium falciparum parasite is transmitted in its sexual gametocyte stage from man to mosquito and as asexual sporozoites from mosquito to man. Developing gametocytes sequester preferentially in the bone marrow, but mature stage gametocytes are released to the bloodstream. Sexual stage parasite surface proteins are of interest as candidate target antigens for transmission blocking vaccines.
In this study, the transcript profiles of rif and var genes, known to encode surface antigens in asexual blood stage parasites, were investigated at different stages of 3D7/NF54 gametocytogenesis and in sporozoites.
Gametocytes exhibited a rif transcript profile unlinked to the rif and var transcript profile of the asexual progenitors. At stage V, mature gametocytes produced high levels of a single rif gene, PF13_0006, which also dominated the rif transcript profile of sporozoites. All var genes appeared to be silenced in sporozoites.
The most prominent variant surface antigen transcribed in both gametocytes and sporozoites of 3D7/NF54 is a single variant of the RIFIN protein family. This discovery may lead to the identification of the parasites binding ligands responsible for the adhesion during sexual stages and potentially to novel vaccine candidates.
疟原虫寄生虫在其有性配子体阶段从人传播到蚊子，在无性孢子阶段从蚊子传播到人。发育中的配子体优先在骨髓中隔离，但成熟阶段的配子体被释放到血液中。性阶段寄生虫表面蛋白是作为传播阻断疫苗候选靶抗原的研究热点。
在这项研究中，我们研究了 3D7/NF54 配子体发生的不同阶段和孢子虫中已知编码无性血期寄生虫表面抗原的 rif 和 var 基因的转录谱。
配子体表现出与无性祖细胞的 rif 和 var 转录谱无关的 rif 转录谱。在 V 期，成熟的配子体产生高水平的单一 rif 基因 PF13_0006，该基因也主导孢子虫的 rif 转录谱。所有 var 基因似乎在孢子虫中都被沉默了。
在 3D7/NF54 的配子体和孢子虫中转录的最突出的变异表面抗原是 RIFIN 蛋白家族的单一变体。这一发现可能导致鉴定负责性阶段黏附的寄生虫结合配体，并可能导致新的疫苗候选物的发现。
