A universal vaccine candidate against Plasmodium vivax malaria confers protective immunity against the three PvCSP alleles

Malaria is a highly prevalent parasitic disease in regions with tropical and subtropical climates worldwide. Among the species of Plasmodium causing human malaria, P. vivax is the second most prevalent and the most geographically widespread species. A major target of a pre-erythrocytic vaccine is the P. vivax circumsporozoite protein ( Pv CSP). In previous studies, we fused two recombinant proteins representing three allelic variants of Pv CSP (VK210, VK247 and P. vivax -like) to the mumps virus nucleocapsid protein to enhance immune responses against Pv CSP. The objective of the present study was to evaluate the protective efficacy of these recombinants in mice challenged with transgenic P. berghei parasites expressing Pv CSP allelic variants. Formulations containing Poly (I:C) or Montanide ISA720 as adjuvants elicited high and long-lasting IgG antibody titers specific to each Pv CSP allelic variant. Immunized mice were challenged with two existing chimeric P. berghei parasite lines expressing Pv CSP-VK210 and Pv CSP-VK247. We also developed a novel chimeric line expressing the third allelic variant, Pv CSP- P. vivax -like, as a new murine immunization-challenge model. Our formulations conferred partial protection (significant delay in the time to reach 1% parasitemia) against challenge with the three chimeric parasites. Our results provide insights into the development of a vaccine targeting multiple strains of P. vivax .