Immunogenicity of Malaria Vaccine Candidate - Plasmodium Falciparum Merozoite Surface Protein 5 (PfMSP5) Expressed in Bacillus subtilis

Malaria is one of the major health problems of the world. A number of vaccine candidates have been identified and are at different stages of the clinical trials. Wide spread deployment of malaria vaccines requires a cost effective and scalable production platform. We have chosen a non-pathogenic bacterial host, Bacillus subtilis, to produce a malaria vaccine candidate PfMSP5. Merozoite surface protein 5 (MSP5) is present during the asexual stage of Plasmodium falciparum, and is a recognized target that can be used as a subunit vaccine against blood stages of malaria. PfMSP5 was successfully expressed in B. subtilis and recovered from the culture supernatant in single step (nickel-affinity chromatography) purification. B. subtilis derived PfMSP5 induced very strong immune responses in mouse immunization experiments. The antibodies raised against PfMSP5 were reactive with proteins expressed by the parasite as shown by immunofluorescence. Our results conclude that the B. subtilis is an efficient expression host for the production of the malaria vaccine candidate PfMSP5.