A dual-antigen mRNA-lipid polyplex vaccine elicits durable multistage immunity and sterile protection against malaria in mice

Malaria remains one of the most devastating infectious diseases worldwide, predominantly caused by Plasmodium falciparum. Although the RTS,S and R21 vaccines have demonstrated partial efficacy, durable and broad protection across multiple parasite life stages remains an unmet need. Here, we report the development of a lipid-polyplex (LPP)-formulated mRNA vaccine platform targeting both the pre-erythrocytic and blood stages of P. falciparum. We designed mRNA constructs encoding the circumsporozoite protein (PfCSP) and the reticulocyte-binding protein homolog 5 (PfRH5), delivered either individually or as dual-antigen tandem forms. The optimized construct, RH5-T2A-CSP (Mal05), exhibited efficient antigen expression and elicited high-titer, durable antibodies capable of inhibiting sporozoite invasion and erythrocytic growth in vitro. In murine models, Mal05 induced robust Th1-biased CD4⁺ and CD8⁺ T-cell responses and conferred 100% sterile protection against challenge with transgenic Plasmodium berghei expressing PfCSP. Collectively, these findings demonstrate that dual-antigen mRNA-LPP vaccination can establish a potent, multistage immunological barrier by integrating neutralizing antibody activity with strong cellular immunity. Mal05 therefore represents a promising next-generation vaccine candidate with the potential to achieve both pre-erythrocytic and blood-stage protection. More broadly, this work highlights the potential of LPP-based mRNA technology for developing multistage vaccines against complex parasitic pathogens.