Expression, purification and characterization of allelic variants of MSP-1₄₂ from Indian Plasmodium falciparum isolates

Abstract

The C-terminal 19 and 42 kDa fragments of Plasmodium falciparum merozoite surface protein 1 (MSP-1) have shown to be protective in animals against lethal parasite challenge. The MSP-1₁₉ being highly conserved may lack sufficient number of T-cell epitopes in order to elicit a broader response in genetically diverse populations. The inclusion of additional epitopes from the N-terminal MSP-1₄₂ has shown to enhance the protective efficacy of MSP-1₁₉ vaccine. In an attempt to examine the strain specific immunogenicity to MSP-1, we have cloned and expressed three diverse allelic variants of MSP-1₄₂ from Indian P. falciparum isolates in bacteria. Among three alleles, one was extremely rare and not been found before. These purified and refolded recombinant products were recognized by conformation specific monoclonal antibodies and hyper-immune sera. Immunization of mice and rabbits with the purified proteins generated high titer biologically active polyclonal antibodies supporting further development of this vaccine candidate antigen.