title: Immunological responses to a 39.8kDa Plasmodium vivax tryptophan-rich antigen (PvTRAg39.8) among humans.
abstract: Tryptophan-rich protein from P. yoelii called PypAg3 had shown protection in a murine model. We describe here its P. vivax orthologue named PvTRAg39.8 which is expressed during schizont stages of the parasite. The transcription initiation site was mapped to the -41 nucleotide position from the first AUG codon and thus established the ORF of PvTRAg39.8 which codes for a 322aa long protein. The sequence of this protein is highly conserved among the P. vivax isolates. Recombinant PvTRAg39.8 was expressed in E. coli, purified to electrophoretic homogeneity, and used for immunological studies. A majority of P. vivax-exposed individuals (90%, n=50) contained antibodies against the recombinant PvTRAg39.8. There was a switching of immunoglobulin isotypes against this antigen from IgG1 to IgG4 among individuals from the acute phase of P. vivax infection to convalescence. The PBMCs of 80% of the total 20 P. vivax-exposed individuals showed proliferation when stimulated with this antigen. The cytokine pattern produced by the PBMCs of the P. vivax-exposed individuals, after stimulation with this antigen, indicated a mixed type of immune response with a distinct bias towards the Th2 anti-inflammatory profile. Because of its high natural immunogenicity, conserved nature, and the protective properties of its P. yoelii counterpart, this protein may be a potential candidate for developing the immunotherapeutic reagents.
authors.affiliation: Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
authors.forename: Sheena
authors.initials: S
authors.lastname: Garg
authors.forename: Shyam S
authors.initials: SS
authors.lastname: Chauhan
authors.forename: Neeru
authors.initials: N
authors.lastname: Singh
authors.forename: Yagya D
authors.initials: YD
authors.lastname: Sharma
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D000953:Antigens, Protozoan / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D002874:Chromosome Mapping; D016207:Cytokines / Q000097:blood / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008213:Lymphocyte Activation; D016780:Malaria, Vivax / Q000276:immunology*; D010966:Plasmodium vivax / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D020449:Repetitive Sequences, Amino Acid; D020539:Sequence Analysis, Protein; D014364:Tryptophan / Q000378:metabolism
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D016207:Cytokines; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D014364:Tryptophan