Novel and cost-effective refolding of a recombinant receptor binding domain of Plasmodium falciparum EBA-175

•The process used in the present study is novel and cost-effective.•Scale up studies showed sustainable and promising results in refolding efficiency and yield.•Refolded protein is functionally active as revealed by erythrocyte binding and ELISA assays.

Plasmodium falciparum erythrocyte binding antigen (EBA-175), which is a 175 kDa protein, binds with sialic acid residues on glycophorin A during invasion of human erythrocytes. Receptor-binding residues of EBA-175 lie in a conserved, amino-terminal, cysteine-rich region, region F2 of EBA-175 (PfF2), that is homologous to the binding domains of other erythrocyte binding proteins. Recombinant PfF2 was expressed in Escherichia coli, purified from inclusion bodies, renatured by rapid dilution in presence of proline and purified to homogeneity by ion-exchange chromatography. Recombinant PfF2 was refolded at higher concentrations with improved refolding efficiency and yield. The refolded protein was characterized using biochemical methods and shown to be pure, homogenous and functional as it binds human erythrocytes with specificity. Immunization of mice and rabbits with recombinant PfF2 formulated with Freund’s and Montanide ISA720 adjuvants, elicited high and potent antibody responses. These observations support the development of a novel and cost-effective process for production of recombinant PfF2, a blood stage vaccine candidate for P. falciparum malaria.

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