title: Cross-reactive cellular immune response to circumsporozoite proteins of Plasmodium vivax and P. falciparum in malaria-exposed individuals.
abstract: Acquired immunity against the recombinant circumsporozoite protein of P. falciparum (rPfCS) or P. vivax (rPvCS) was studied in two malarious areas of the Brazilian Amazon. Cellular responsiveness, evaluated by proliferative assays, was detected in about 45% of individuals who had recovered from recent acute malaria infections. Peripheral blood mononuclear cells of individuals whose last malaria infection was by P. vivax responded more to the rCS proteins than those who had P. falciparum. Since in P. vivax infections hypnozoites in the liver retain CS antigen, this stage may have contributed to the increased cellular response. The unexpected result was that in primoinfections by P. falciparum or P. vivax the proliferative response did not correspond to the rPfCS and rPvCS, respectively. Furthermore, among the malaria-exposed individuals, there was a positive correlation between the intensity of the responses to the two rCS proteins. Our results suggest that cross-reactive epitopes exist in the CS protein of P. falciparum and P. vivax. In the areas studied, the frequency of antibodies against rPvCS and/or rPfCS ranged from 43% to 11%. Species-specific antibodies against the CS protein were detected in the primoinfected individuals. Some individuals living in the endemic area but with no clinical history of malaria were positive by serology (8%) or by in vitro proliferation (21%). However, antibodies and cellular responses against rCS were detected only in malaria-exposed individuals, since those living outside the endemic area were all negative.
authors.affiliation: Departamento de Parasitología, Universidade Federal de Minas Gerais, Brazil.
authors.forename: L H
authors.initials: LH
authors.lastname: Carvalho
authors.forename: C J
authors.initials: CJ
authors.lastname: Fontes
authors.forename: A A
authors.initials: AA
authors.lastname: Fernandes
authors.forename: H C
authors.initials: HC
authors.lastname: Marinuzzi
authors.forename: A U
authors.initials: AU
authors.lastname: Krettli
mesh_terms: D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D000953:Antigens, Protozoan / Q000276:immunology*; D002455:Cell Division; D006801:Humans; D007111:Immunity, Cellular; D007074:Immunoglobulin G / Q000276:immunology; D008288:Malaria / Q000097:blood / Q000276:immunology*; D010963:Plasmodium falciparum / Q000276:immunology*; D010966:Plasmodium vivax / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; C041595:circumsporozoite protein, Protozoan