Genetic restriction of the murine humoral response to a recombinant Plasmodium vivax circumsporozoite protein.

The antibody response of inbred and congenic strains of mice immunized with a recombinant Plasmodium vivax circumsporozoite protein was investigated. Only mice of the H-2k and H-2a haplotypes developed antibodies that react with P. vivax sporozoite in an indirect immunofluorescence assay and with the recombinant protein in enzyme-linked immunosorbent assay. Congenic recombinant strains were used to map Ir gene control to the I-Ak locus. A similar pattern of genetic restriction was found when congenic strains were immunized with a carrier-free synthetic peptide corresponding to the repeat region of the P. vivax circumsporozoite protein. The results suggest that the ability of T helper cells to recognize a T cell epitope(s) in the repeat region of the P. vivax circumsporozoite protein is genetically restricted.