title: Immunogenicity of the nonrepetitive regions of the circumsporozoite protein of Plasmodium knowlesi.
abstract: The circumsporozoite antigen (CS) of the simian malarial parasite Plasmodium knowlesi consists of tandemly repeated immunodominant peptide units that are variable and may play a role in evading the immune system. To study the immunogenicity of this antigen in the absence of the immunodominant repeats, the entire nonrepetitive region of the antigen was expressed in Escherichia coli as two fusion proteins with glutathione-S-transferase (GST) representing the amino terminal (GST-CSN) and the carboxy terminal domains (GST-CSC) of the CS antigen. The immunogenicity of these fusion proteins was studied in rabbits and different strains of mice. Antibody raised against both the CSN and CSC domains in both rabbits and every strain of mice recognized the native protein, as detected by immunofluorescence assay (IFA) using P. knowlesi sporozoites. A positive IFA reaction was also obtained with P. vivax sporozoites using antisera raised against the CSC domain. High titer antisera were raised in rabbits against both the domains, whereas mice showed comparatively low titers. On Western blots, mice showed specific response against the CSC domain. In both rabbits and mice, significant titers of antibodies were raised against region II, which has been shown to be the putative sporozoite binding site for hepatocytes in the case of P. falciparum.
authors.affiliation: Molecular Biology Unit, Tata Institute of Fundamental Research, Bombay, India.
authors.forename: S
authors.initials: S
authors.lastname: Sharma
authors.forename: A
authors.initials: A
authors.lastname: Goswami
authors.forename: N J
authors.initials: NJ
authors.lastname: Singh
authors.forename: L
authors.initials: L
authors.lastname: Kabilan
authors.forename: S S
authors.initials: SS
authors.lastname: Deodhar
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis / Q000276:immunology; D000953:Antigens, Protozoan / Q000737:chemistry / Q000276:immunology*; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005455:Fluorescent Antibody Technique; D007106:Immune Sera / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D016790:Plasmodium knowlesi / Q000737:chemistry / Q000276:immunology*; D015800:Protozoan Proteins / Q000737:chemistry / Q000276:immunology*; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007106:Immune Sera; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; C041595:circumsporozoite protein, Protozoan