A Miniaturized Assay to Evaluate Plasmodium cynomolgi and Plasmodium knowlesi as Models for Prioritizing Plasmodium vivax Vaccine Targets.

Plasmodium vivax vaccine discovery lags behind Plasmodium falciparum due to the absence of a reliable in vitro culture system. We developed a miniature 384-well assay for the evolutionarily related parasite species Plasmodium cynomolgi and Plasmodium knowlesi, deploying it for screening invasion inhibition efficacy of antibodies elicited against 8 P. vivax proteins. All 8 antibodies showed consistent inhibition across both P. knowlesi and P. cynomolgi species, correlating with inhibition in ex vivo P. vivax isolates. The use of simian malaria parasites and this assay represent a robust, high-throughput method for prioritizing P. vivax blood-stage vaccine candidates.