Ookinete antigens of Plasmodium berghei. Appearance on the zygote surface of an M_r 21 kD determinant identified by transmission‐blocking monoclonal antibodies

Abstract

Zygotes and ookinetes of the rodent malaria Plasmodium berghei can be enriched 50-fold, from whole blood cultures by ammonium chloride lysis. Three monoclonal antibodies (MoAbs) raised against such enriched preparations specifically bind to a determinant of Mr 21 kD as assessed by 125I-labelled goat anti-mouse IgG probed immunoblots of Western transfers of SDS-PAGE gels. Indirect immunofluorescence indicates that the 21 kD determinant bound by specific MoAbs, whilst not detectable on gametocytes or gametes, appears on the parasite surface within 2 h of exflagellation/fertilization and increases thereafter. The three MoAbs specifically binding the 21 kD determinant block oocyst development in mosquitoes by at least 90%, as assessed either by in-vitro membrane feeds or by live feeds on passively immunized mice. These MoAbs reduce ookinete formation in vitro by between 52 and 100%. Possible mechanisms of action of these MoAbs are discussed.

A NIMA-related Protein Kinase Is Essential for Completion of the Sexual Cycle of Malaria Parasites

“…To obtain a measure of exflagellation, centers of movement were then counted in 10 microscopic fields (ϫ40 objective, ϫ10 ocular lens), containing ca. 15,000 RBC, by phase contrast microscopy between 15 and 25 min postinduction, when exflagellation activity is maximal (28,29). To compare exflagellation levels between parasite clones in Fig.…”

“…After 1 h at 19°C to allow fertilization to take place, cultures were diluted with 0.5 ml of ookinete medium, transferred to a 24-well plate, and cultured at 19°C for a further 21-24 h. For direct immunolabeling cultured cells were pelleted for 2 min at 800 ϫ g and then labeled for 1 h on ice in 50 l of ookinete medium containing Cy3-conjugated mouse monoclonal antibody 13.1 specific for P28 (29) and Hoechst 33342 (Sigma) to a final concentration of 5 g/ml. P28-positive cells were than counted in a hemocytometer or observed under Vaseline®-rimmed cover slips with a Leica DMR fluorescence microscope equipped with a Leica DC500 digital camera.…”

Interaction between Host Complement and Mosquito-Midgut-StagePlasmodium berghei

“…Although mice are usually used as vertebrate hosts for P. berghei, rats are also suitable hosts for growth and transmission of this parasite (23). Ookinete cultures were prepared as described previously (31). If required, the cultures were depleted of red blood cells at approximately 1 h postgametogenesis (i.e., following fertilization), by either density centrifugations (12% Nycodenz) or dextran precipitation of red blood cells (1).…”

Inhibition complète de la transmission cyclique par immunisation contre les ookinètes dePlasmodium bergheiAnka

“…Des anticorps monoclonaux capables d'inhiber la transmission cyclique ont été utilisés pour identifier les antigènes de surface, cibles de l'immunité inhibitrice de la transmission cyclique. Certains anticorps monoclonaux bloquent la fécondation tandis que d'autres empêchent le dévelop pement du zygote Vermeulen et al, 1985 ;Kaushal et al, 1983et Winger et al, 1988.…”