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

摘要

P. falciparum Merozoite Surface Protein-I (MSP-I) is a leading erythrocytic-stage vaccine candidate. It is proteolytically processed to several fragments, and may play a role in binding and/or invasion of erythrocytes. During erythrocyte invasion secondary processing on MSP-1(42) gives a 33kDa and a 19kDa fragment (MSP-1(19)). Although, MSP-1(19) is a target for parasite inhibitory mAbs and protective immunity, it appears to lack T-helper epitopes. Since antibody is likely the effector mechanism induced by MSP-(42), it is important to insure that recombinant vaccines based upon this antigen be folded correctly and contain T-helper epitopes that will enhance induction of humoral responses. We developed recombinant MSP-1(42) that was structurally correct based on positive reactivities with conformation-dependent mAbs, including 12. 10,12.8. 7.5, 7.2, and I El. Purification over three chromatographic steps that include nickel affinity chromatography, Q-substituted and CM-substituted resins, yielded protein that was 95% pure and exceeded FDA endotoxin standards. Mice seroconverted following immunization with recombinant MSP-1(42). Safety and immunogenicity testing in Rhesus monkeys revealed that MSP-1(42) /SBAS2, was safe and induced MSP-1(42)-specific antibody responses.