Role of Plasmodium berghei ookinete surface and oocyst capsule protein, a novel oocyst capsule-associated protein, in ookinete motility

Kazuhiko Nakayama,Jun Hakozaki,Asako Haraguchi,Kodai Kusakisako,Akira Soga,Makoto Sugiyama,Shinya Fukumoto,Yu Kitahara,Yuta Kimura,Hiromi Ikadai

doi:10.1186/s13071-021-04868-2

Abstract

BackgroundPlasmodium sp., which causes malaria, must first develop in mosquitoes before being transmitted. Upon ingesting infected blood, gametes form in the mosquito lumen, followed by fertilization and differentiation of the resulting zygotes into motile ookinetes. Within 24 h of blood ingestion, these ookinetes traverse mosquito epithelial cells and lodge below the midgut basal lamina, where they differentiate into sessile oocysts that are protected by a capsule.MethodsWe identified an ookinete surface and oocyst capsule protein (OSCP) that is involved in ookinete motility as well as oocyst capsule formation.ResultsWe found that knockout of OSCP in parasite decreases ookinete gliding motility and gradually reduces the number of oocysts. On day 15 after blood ingestion, the oocyst wall was significantly thinner. Moreover, adding anti-OSCP antibodies decreased the gliding speed of wild-type ookinetes in vitro. Adding anti-OSCP antibodies to an infected blood meal also resulted in decreased oocyst formation.ConclusionThese findings may be useful for the development of a transmission-blocking tool for malaria.Graphical abstract

Highlights

Plasmodium sp., which causes malaria, must first develop in mosquitoes before being transmitted
oocyst capsule protein (OSCP) is expressed in ookinetes and is a component of the oocyst capsule A PlasmoDB search performed for proteins expressed on the P. berghei ookinete surface and that are part of the oocyst capsule led to the identification of OSCP (PBANKA_1025100)
To investigate the localization of OSCP expression, we labeled ookinetes and oocysts with anti-OSCP antibodies using immunofluorescence assays (IFAs). These Immunofluorescence assays (IFA) indicate whether OSCP is present in ookinetes

Summary

Introduction

Plasmodium sp., which causes malaria, must first develop in mosquitoes before being transmitted. Gametes form in the mosquito lumen, followed by fertilization and differentiation of the resulting zygotes into motile ookinetes. Within 24 h of blood ingestion, these ookinetes traverse mosquito epithelial cells and lodge below the midgut basal lamina, where they differentiate into sessile oocysts that are protected by a capsule. After the mosquito ingests an infected blood meal, parasites form gametes, followed by fertilization and differentiation of the resulting zygotes into motile ookinetes that traverse the midgut epithelium and lodge below the midgut basal lamina. It takes > 20 h from blood ingestion until the ookinete arrives at the midgut basal lamina. Many sporozoites are formed and released into the hemolymph, increasing parasite numbers by several thousand fold [5]

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