Fertilization Mechanisms of the Rodent Malarial Parasite Plasmodium berghei

Abstract

Malaria, caused by Plasmodium spp., is transmitted by anopheline mosquitoes. When male and female gametes are introduced into the mosquito mid- gut, they reproduce sexually and proliferate, at which time the mosquito becomes infectious to vertebrates. It has been proposed that fertilization is a critical target in the parasite life cycle for the reduction of malarial prevalence. Although under- standing parasite fertilization is crucial for the control of malaria, the precise molec- ular mechanisms involved have long remained unknown. Generative cell-specifi c 1 (GCS1) has been reported to be a critical fertilization factor in angiosperms. It was subsequently shown that the function of GCS1 is conserved in both the rodent malaria parasite Plasmodium berghei and the green alga Chlamydomonas rein- hardtii . Moreover, a GCS1 -like gene has been detected in the genomes of various organisms, suggesting that it plays a conserved role in gamete interaction. As GCS1 is thought to act as a membrane-anchoring protein in male gametes, a female coun- terpart is assumed to exist. To reveal the mechanisms involved in parasite fertiliza- tion, it is important to clarify the function of GCS1 and to identify GCS1 partners and other fertilization factors. In this review, I fi rst describe the life cycle of malaria parasites, focusing on gametogenesis and fertilization and the underlying mecha- nisms. I then discuss the functions of GCS1 at the time of gamete interaction. Finally, I consider whether parasite fertilization factors, including GCS1, might be utilized in the development of antimalarial vaccines. Keywords