ABSTRACT
Malaria is a major cause of mortality and morbidity globally. Great efforts have been made in the prevention and the elimination of malaria, especially in controlling the malaria vector, the mosquito. Another promising approach would be the development of malaria vaccines. Malaria vaccine studies can be focused on the pre-erythrocytic-stage antigens and the blood-stage antigens, and on the transmission blocking agents targeting the malaria gametocytes. The blood-stage antigens are the leading candidates in malaria vaccine development, as the blood-stage parasites are responsible for causing symptomatic malaria. Human acquired immunity largely targets on blood-stage antigens. This review focuses on one of the most extensively studied blood-stage antigen, the merozoite surface protein-1 (MSP-1), specifically on its evaluation and immunogenicity in rodents and primate models, and its safety and immunogenicity in human clinical trials.
Subject(s)
Malaria VaccinesABSTRACT
Malaria causes high global mortality and morbidity annually. Plasmodium knowlesi has been recognised as the fifth human Plasmodium sp. and its infection is widely distributed in Southeast Asia. Merozoite surface protein-119 (MSP-119) appears as a potential candidate for malaria blood stage vaccine as it could induce protective immunity. In this study, codon optimized P. knowlesi MSP-119 (pkMSP-119) was expressed and purified in yeast Pichia pastoris expression system. The purified recombinant protein was further evaluated using Western blot assay using knowlesi malaria, non-knowlesi human malaria, non-malarial parasitic infections and healthy serum samples (n = 50). The sensitivity of purified pkMSP-119 towards detection of knowlesi infection was as 28.6% (2/7). pkMSP-119 did not react with all nonmalarial parasitic infections and healthy donor sera, yet reacted with some non-knowlesi human malaria sera, therefore lead to a specificity of 86.0% (37/43).