Immunogenicity Analysis of Recombinant Plasmodium malariae AMA-1 Antigen as a Potential Vaccine Candidate

Abstract The apical membrane antigen-1 (AMA-1) is a potential candidate for the development of a malaria vaccine targeting Plasmodium parasites. Although studies on the immunogenicity of AMA-1 are abundant for Plasmodium falciparum and Plasmodium vivax, there is a notable scarcity of information for Plasmodium malariae. In this study, we expressed recombinant PmAMA-1 using an Escherichia coli expression system. The integrity of the rPmAMA-1 was verified through western blotting and indirect immunofluorescence assays. The immunogenic characteristics of rPmAMA-1 were assessed in BALB/c mice, utilizing the purified protein emulsified in Freund’s adjuvant. The findings revealed that mice immunized with rPmAMA-1 generated significantly elevated specific IgG antibodies, with IgG1 being the predominant component. The immune responses exhibited Th1 (IL-2, IFN-γ, and TNF-α), Th2 (IL-4, IL-6, and IL-10) and Th17 (IL-17a) phenotypes, but with a notable bias on Th1 response. Furthermore, the antisera against rPmAMA-1 from immunized mice enabled effective recognition of its native counterpart on P. malariae parasites, affirming the correct conformation and folding of the recombinant protein. The immune profiling study strongly suggests that PmAMA-1 would likely evoke a substantial immune response in vivo, positioning it as a promising candidate for vaccine development.