Malaria, caused by the Plasmodium parasite, remains a relentless and destructive infectious disease, disproportionately affecting children in Sub-Saharan Africa, due in part to the absence of a highly effective, widely deployable malaria vaccine. Lipid nanoparticle (LNP) vaccines are a promising approach for vaccine development, especially against pathogens such as Plasmodium, which have proven historically difficult to vaccinate against. When coupled with the glycolipid adjuvant 7DW8-5 at a 5ug LNP to 0.5ug adjuvant ratio, malaria-targeting LNP formulations confer protection in mouse models. However, the optimal vaccine-to-adjuvant ratio and the mechanisms underlying 7DW8-5-mediated protection remain unclear. Here, we present a study that aims to refine dosing strategies and elucidate the role of CD8+ T and NKT cells in adjuvant-induced protection in a human-translatable mouse model. Different groups of mice will be vaccinated with varying LNP-to-adjuvant ratios, and immune response will be assessed via ELISPOT 28 and 56 days post-vaccination. Furthermore, we will use ELISA to reveal variations in innate immune response between groups 3 hours after vaccine administration. In parallel, we will investigate the necessity of CD8+ T cells and/or NKT cells in protecting from malaria challenge. Mice will be vaccinated using the standardized LNP-to-adjuvant ratio and treated with depletion antibodies targeting CD8+T or NKT cells 24 hours before challenge with Plasmodium sporozoites. Protection will be assessed via blood smear analysis. Our findings will reveal optimal dosing strategies for malaria-specific LNP vaccines and provide insight into the immunological mechanisms behind 7DW8-5-driven protection. This research will contribute to the development of effective nanoparticle-based malaria vaccines — a necessary innovation to help relieve the global malaria burden.

Malaria is a mosquito-borne infectious disease caused by Plasmodium parasites and in 2023 caused an estimated 597,000 deaths. Although two currently approved malaria vaccines are available, they offer insufficient protection in endemic populations, which prompts the need for new vaccines. Here we tested several lipid nanoparticle (LNP) vaccines and quantified the number of surviving parasites in vaccinated mice challenged with Plasmodium yoelii sporozoites. To quantify surviving parasites, we utilized the Plasmodium 18S rRNA reverse transcription PCR assay, which is a highly sensitive assay that can quantify the amount of Plasmodium parasites in liver or blood samples. The assay works by amplifying and detecting parasite 18S rRNA in a sample through specific primers, probes and quenchers for mouse GAPDH mRNA and pan-Plasmodium 18S rRNA and can be used to quantify the burden of Plasmodium in a sample. Through the 18S assay, we identified LNP formulations that most effectively protected against rodent malaria. Notably, these LNPs required the adjuvant 7DW85 to be protective.  In the absence of the adjuvant, fewer mice vaccinated with LNPs were protected against rodent malaria. Together, we identified our leading LNP vaccines, which we continue to optimize with the goal of attaining sterile protection against rodent malaria.