Production of a Recombinant E. coli Expressed Malarial Vaccine from the C-Terminal Fragment of Plasmodium Falciparum 3D7 Merozoite Surface Protein-1

Abstract

Abstract : Malarial blood stage antigens can produce humoral immunity by induction of protective antibodies to epitopes on surface antigens on parasites. The merozoite surface protein-1 (MSP1) of P. falciparum is a major blood-stage vaccine candidate. MSP1 may play a role in binding and/or infection of erythrocytes by merozoites (parasites) during red blood cell invasion. The C-terminal fragment of MSP1, MSP1(sub 19), is highly conserved among all known strains of P. falciparum. immunization with recombinant proteins that have native-like conformations may elicit long-lasting protective immunity that mimics the natural immunity. We have used bacterial expression to tightly regulate transcription and translation of MSP1(sub 42). Plasmids that encode MSP1(sub 42) were prepared and tested for their ability to express recombinant protein. A three column purification scheme that included Ni(+2) metal chelate chromatography, anion and then cation exchange chromatography, yielded greater than 95% pure MSP1(sub 42). Immunoreactivity with mAbs showed that recombinant MSP1(sub 42) was conformationally similar to native MSP1. The objectives were to develop recombinant MSP1(sub 42) molecules that were structurally correct, to develop fermentation and purification processes that could be scaled-up for large-scale processes, and ultimately, to advance these products into human clinical trials.