Renu Sharma et al CHEMICAL SYNTHESIS OF HISTIDINE RICH PROTEIN (HRP-2) ANTIGEN PEPTIDE FROM PLASMODIUM FALCIPARUM AND DETECTION OF ITS IMMUNOGENICITY

Malaria is the one of the most prevalent human infections in the world. It causes significant morbidity and mortality worldwide, including countries with mainly imported malaria. Malaria parasite Plasmodium falciparum is the most common cause of severe and life threatening malaria and accounts over 1 million deaths every year. Microscopy of Giemsa-stained thick & thin films remains the current gold standard for diagnosis. Although it has good sensitivity and allows species diagnosis, it is time consuming, required equipments & skilled personnel. Antigen tests based on antigen capture assay are capable of detecting fewer parasites and of producing the results more quickly. Such antigen which is shown promising results is plasmodium falciparum histidine rich protein-2 (PfHRP-2). HRP-2 is contained tendem repeats of the sequences AHH & AHHAAD and has B-cells epitopes that allows its detection. In this study chemically HRP-2 antigen peptides were synthesized by solid phase technique and purified by HPLC gel chromatography. Microsphere (PLGA &PVA) entrapped peptides are injected to mice and rabbits subsequent booster doses. The high titre/affinity antibodies raised against these peptide antigens were estimated by indirect ELISA technique. The peptide specific peak absorbance varied from 0.6 to 2.6. The variation in the titre of antibody generated in mice and rabbits depend upon the individual immune responsive capacity. Incremental increase in antibody titre with microscope delivery may result in sustained release of the antigen. Our studies show that chemically synthesized peptides of PfHRP-2 delivered in microsphere were able to generate immune response that can be quantified. This paves for development of tools for early diagnosis of malaria.