The C-terminal region of the Plasmodium berghei gamete surface 184-kDa protein Pb184 contributes to fertilization and male gamete binding to the residual body

Abstract

Background Malaria is a global health concern, caused by parasites of the Plasmodium genus, which undergo gametogenesis in the midgut of mosquitoes after ingestion of an infected blood meal. The resulting male and female gametes fuse to form a zygote, which differentiates into a motile ookinete. After traversing the midgut epithelium, the ookinete differentiates into an oocyst on the epithelial basal side. Methods We investigated membrane proteins with increased gene expression levels from gametes to oocysts in P. berghei, utilizing the PlasmoDB. As a result, 184 kDa membrane protein, Pb184 was selected. After confirming the expression of Pb184 through immunofluorescence staining, we examined whether Pb184 is involved in the fertilization using antibodies targeting the C-terminal region of Pb184 and biotin-labeled C-terminal region peptides of Pb184. Results We found that Pb184 is expressed on the surface of male and female gamete, respectively. The antibody inhibited zygote and ookinete formation in vitro. When mosquitoes fed on parasite-infected blood containing the antibody, oocyst formation decreased on the second day after feeding. Synthesized a biotin-labeled peptides matching the C-terminal region of Pb184 bound to the female gamete and the residual body of male gametes, and inhibiting differentiation into ookinetes in the in vitro culture system. Conclusions These finding may be useful for the further studying in the fertilization mechanism of Plasmodium protozoa. In addition, there is a potential for their application as future tools to prevent malaria transmission.