Korea vaccinia viral vectored vaccine expressing 33 kDa fragment of Plasmodium vivax merozoite surface protein 1 elicited strong humoral immune responses in mice

Abstract

Vivax malaria is the most widely distributed human malaria in the world. Relapse and recurrence in temperate regions are major issues related to vivax malaria. Until now, no adequate vaccines for vivax malaria were developed. In this study, a recombinant attenuated Korea vaccinia virus (KVAC103) expressing the 33 kDa fragment of merozoite surface protein-1 (PvMSP133), the most abundant surface protein of Plasmodium vivax, was generated and evaluated for its potential as an anti-malarial vaccine. The PvMSP133-expressing virus (KVAC-PvMSP133) was generated in Vero cells by homologous recombination with KVAC103 and then purified. The vaccine was inoculated twice with 3-week intervals into the mice subcutaneously. Next, cellular and humoral immune responses in the mice were examined. KVAC-PvMSP133 elicited weak CD3+, CD4+, and CD8+ T-cell responses in the spleen of vaccinated mice. However, the production of PvMSP133-specific IgG was significantly increased in the peripheral blood of the mice. Among the immunoglobulin subtypes, IgG2b showed the strongest effects. Serial KVAC- PvMSP133 vaccination elicited strong humoral immune responses rather than cellular immune responses in mice. KVAC103 vector expressing Plasmodium antigen(s) and antibodies elicited by the vaccination can be used as a platform for producing protective anti-malarial vaccine.