Identification of Caucasian CD4 T cell epitopes on the circumsporozoite protein of Plasmodium vivax. T cell memory.
We have identified a population of Caucasians with a defined past history of infection with Plasmodium vivax malaria. Using purified synthetic peptides overlapping the sequence of the circumsporozoite protein, we determined the percentage of individuals whose T cells proliferated or secreted IFN-gamma in response to peptide stimulation, for both this population and a population of nonmalaria-exposed control individuals. A number of peptides were recognized by both groups, but 11 peptides were uniquely recognized by the exposed population, and thus represented malaria-specific T cell epitopes. CD4 T cells were found to be responsible for the proliferative response. Humans last exposed to vivax sporozoites as long ago as 49 yr responded as well or better to these malaria-specific epitopes as individuals exposed within the previous month. Since such malaria-induced memory response may not be a feature of Plasmodium falciparum infections, and since P. falciparum does not have a persisting hypnozoite stage, our data argue that the persistence of T cell memory to vivax epitopes may result from antigenic persistence in the liver.
Bilsborough
J
J
Molecular Immunology Unit, Queensland Institute of Medical Research, Brisbane, Australia.
Carlisle
M
M
Good
M F
MF
D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D000939:Epitopes / Q000032:analysis*; D006801:Humans; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis; D008875:Middle Aged; D008969:Molecular Sequence Data; D010966:Plasmodium vivax / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000502:physiology
D000939:Epitopes; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan; D007371:Interferon-gamma