Isolation of viable Plasmodium falciparum merozoites to define erythrocyte invasion events and advance vaccine and drug development
Michelle J Boyle, Danny W Wilson, Jack S Richards, David T Riglar, Kevin KA Tetteh, David J Conway, Stuart A Ralph, Jake Baum, James G Beeson
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA | NATL ACAD SCIENCES | Published : 2010
During blood-stage infection by Plasmodium falciparum, merozoites invade RBCs. Currently there is limited knowledge of cellular and molecular invasion events, and no established assays are available to readily measure and quantify invasion-inhibitory antibodies or compounds for vaccine and drug studies. We report the isolation of viable merozoites that retain their invasive capacity, at high purity and yield, purified by filtration of highly synchronous populations of schizonts. We show that the half-life of merozoite invasive capacity after rupture is 5 min at 37 degrees C, and 15 min at room temperature. Studying the kinetics of invasion revealed that 80% of invasion events occur within 10..View full abstract
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We thank Alan Cowman (Walter and Eliza Hall Institute, Australia), Paul Gilson and Brendan Crabb (Burnet Institute, Australia), Tony Hodder (Walter and Eliza Hall Institute, Australia), and Robin Anders (Latrobe University, Australia) for antibodies to RAP1, MSP1-19, AMA1, and MSP2, respectively, and helpful advice on the study; Julia Cutts for important experimental ideas; and Salenna Elliott for critical reading of the manuscript and the WEHI flow-cytometry services. RBCs and serum for parasite culture were provided by the Red Cross Blood Bank (Melbourne, Australia). Funding for the study was provided by a National Health and Medical Research Council of Australia Project grant and Career Development awards (J.G.B., J.B., and S.A.R.); a Postgraduate Research Scholarship (J.S.R.) and Independent Research Institutes Infrastructure Support Scheme grant; an Australian Research Council Future Fellowship (J.G.B.) and Grant FT0990350 (to S.A.R.); an Australian Postgraduate Award (M.J.B. and D.R.); an OIS Grant from the Victorian State Government; a Pratt Foundation Postgraduate Scholarship (D.T.R.); and a Top-Up Postgraduate Award from the University of Melbourne, School of Medicine, Dentistry and Health Sciences (M.J.B.).