Reestablishing Plasmodium cynomolgi continuous culture (Part I)

Background: Plasmodium cynomolgi, the simian malaria parasite which is genetically and phenotypically similar to P. vivax has been widely used as the model in understanding the pathogenesis and biology of P. vivax. Various critical discoveries of P.vivax originated from in vivo studies with P.cynomolgi. This includes the discovery of the pre-erythrocytic cycle, the dormant hypnozoites and the development of the relapse model for drug screening of the pre-erythrocytic stages. Even though continuous culture of P.cynomolgi erythrocytic stages was first demonstrated in the 1980s, it has not been replicated since. Materials and Methods In this study, we attempted to re-establish a robust and reproducible continuous culture of P. cynomolgi; by identifying a suitable P. cynomolgi clone and optimizing and upscaling the methods of Ng et al 1981. After molecular characterization, we also used a variety of methods to phenotype this strain of P. cynomolgi (AFM, SEM, Dual micropipette aspiration, Amnis FACs, Invasion inhibition and Medium throughput antimalarial susceptibility assays). Results and Conclusions. We can reproducibly maintain high parasitemias (>4% infection) in continuous culture for as long is necessary. However, our method still requires the use of monkey red blood cells. None the less these in vitro P. cynomolgi parasites retain key phenotypic characteristics with its human counterpart, P. vivax thus making it a valuable model for drug and vaccine research.