A recombinant multi-epitope, multi-stage malaria vaccine candidate expressed in Escherichia coli

To construct and evaluate a recombinant multi-epitope, multistage malaria vaccine candidate expressed in Escherichia coli (E. coli).

A hybrid gene (HGF) encoding several putative immunodominant T or T/B epitopes from MSP-1, MSP-2, Pf155/RESA of Plasmodium falciparum (P. falciparum) and two immune-stimulating epitopes from interleukin-1 and tetanus toxin was synthesized. Two copies of HGF and a copy of gene encoding Pattaroyo's Spf66 were connected together to construct a sandwich hybrid gene HGFSP. The gene was cloned into an expression vector pWR450-I for production of a fusion protein with beta-galactosidase. Efficacy of this vaccine candidate in inducing specific immunity against malaria parasites was evaluated.

Immunization of different species of animals with purified recombinant peptide showed that the peptide was able to induce remarkable antibody response to the immunized peptide as well as falciparum malaria parasites. The epitopes included in the construct could induce antibodies against the intact parasite proteins as demonstrated by western blotting, indicating the epitopes retained their antigenicity in the new peptide construct. Antibodies from animals immunized with recombinant HGFSP peptide exhibited good ability in inhibition of the in vitro growth of malaria parasites, augmentation of phagocytosis of the parasites or infected RBC by phagocytes, and facilitation of antibody dependent cell mediated cytotoxicity to the cultured malaria parasites.

The recombinant peptide seems to be a potential candidate which is valuable for further investigation.