Transmission Blocking Vaccine for P. vivax Malaria

Principal Investigator : Wang Nguitragool, Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University

Project Status : On-going

Project Summary

Global efforts to curtail the spread of malaria have been very successful. However, one key stumbling block is the proportional rise in the total number of cases of plasmodium vivax. In areas where both p. vivax and plasmodium falciparum coexist, we can see a rise in the number of infections due to p. vivax increase as the number of p. falciparum decrease. This worrying trend suggests that p. vivax is more resistant to malarial control and elimination efforts.  One cause is the greater efficacy in its human to mosquito transmission, and disruption of this process shows great promise in p. vivax control efforts. The Wang team is attempting to produce an mRNA vaccine that induce an antibody response that will help block the transmission of p. vivax from humans to mosquitos which will help slow the spread of p. vivax. The issue with the currently available vaccines is that the immune response they induce is neither strong enough nor durable enough to effectively block the transmission of the p. vivax parasite. Further highlighting the need for a novel vaccine to against p. vivax.  The Wang lab has been making significant progress in developing a P. Vivax transmission blocking vaccine. Early studies using a lipid nanoparticle containing mRNA coding for the surface protein Psv25 have been very promising.  Using 2 doses 4 weeks apart, their vaccine candidate has been shown to produce a significantly stronger antibody titer than traditional protein/adjuvant-based vaccines. Next, the efficacy of blocking transmission was tested using the antibodies produced my immunized mice in P. Vivax infected patient blood.  They found the antibodies were able to effectively block all transmission into the mosquitos.  Based on this promising data, the study is awaiting approval for pre-clinical trials.