Modified thawing process yielded a high number of viable-intact erythrocytic stages of the longterm cryopreserved plasmodium vivax malaria

Abstract

Cryopreservation is an important technique for long-term starage of malaria for use in the laboratory as well as preservation of field isolates. For decades, freezing medium containing glycerolyte has been the solution of choice for preservation of the parasites. The current technique available for the preservation of P. falciparum and P. vivax demonstrate successful cryopreservation of parasites in the early stages of the life cycle from both cultureadapted parasites and infected blood samples taken directly from the host. However, parasites in mature stages cannot be preserved by the standard thawing technique. Low recovery of parasites following the freezing and thawing process may be a selective event favoring mutant subpopulation; therefore, it is essential that the preservation technique used is capable of preserving parasites at all stages of its life cycle. In this study, we introduce a modified method of malaria parasite cryopreservation that results in significantly higher parasite recovery of all stages (p<0.001). Higher percentage of mature parasites was recovered from both malarial spices of P. falciparum and P. vivax, when compared the modified thawing method to the standard method (p<0.001). This modified thawing method will enhance opportunity for research in P. vivax strain allowing successful maintenance of long-term in vitro culture, assessment of drug effectiveness and vaccine development studies.