Bacterially expressed and refolded receptor binding domain of Plasmodium falciparum EBA-175 elicits invasion inhibitory antibodies.
Malaria parasites make specific receptor-ligand interactions to invade erythrocytes. A 175 kDa Plasmodium falciparum erythrocyte binding antigen (EBA-175) binds sialic acid residues on glycophorin A during invasion of human erythrocytes. The receptor-binding domain of EBA-175 lies 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 such as Plasmodium vivax Duffy binding protein. We have developed methods to produce recombinant PfF2 in its functional form. Recombinant PfF2 was expressed in Escherichia coli, purified from inclusion bodies, renatured by oxidative refolding and purified to homogeneity by ion-exchange and gel filtration chromatography. Refolded PfF2 has been characterized using biochemical and biophysical methods and shown to be pure, homogenous and functional in that it binds human erythrocytes with specificity. Immunization with refolded PfF2 yields high titre antibodies that efficiently inhibit P. falciparum invasion of erythrocytes in vitro. Importantly, antibodies raised against PfF2 block invasion by a P. falciparum field isolate that invades erythrocytes using multiple pathways. These observations support the development of recombinant PfF2 as a vaccine candidate for P. falciparum malaria.
Pandey
Kailash C
KC
Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, P. O. Box 10504, Aruna Asaf Ali Marg, New Delhi 110067, India.
Singh
Sanjay
S
Pattnaik
Priyabrata
P
Pillai
C R
CR
Pillai
Usha
U
Lynn
Andrew
A
Jain
S K
SK
Chitnis
Chetan E
CE
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood* / Q000276:immunology; D000953:Antigens, Protozoan; D002352:Carrier Proteins / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D004912:Erythrocytes / Q000276:immunology / Q000469:parasitology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006790:Host-Parasite Interactions; D006801:Humans; D017780:Malaria Vaccines / Q000008:administration & dosage / Q000276:immunology; D016778:Malaria, Falciparum / Q000276:immunology / Q000469:parasitology / Q000517:prevention & control; D010963:Plasmodium falciparum / Q000472:pathogenicity*; D011487:Protein Conformation; D017510:Protein Folding; D015800:Protozoan Proteins / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D002352:Carrier Proteins; D017780:Malaria Vaccines; D015800:Protozoan Proteins; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C065668:erythrocyte-binding antigen 175, Plasmodium