Immunogenicity and antigenicity of the N-term repeat amino acid sequence of the Plasmodium falciparum P126 antigen.

The P126 protein, a parasitophorus vacuole antigen of Plasmodium falciparum has been shown to induce protective immunity in Saimiri and Aotus monkeys. In the present work we investigated its immunogenicity. Our results suggest that the N-term of P126 is poorly immunogenic and the antibody response against the P126 could be under a MHC restricted control in C57BL/6(H-2b) mice, which could be problematic in terms of a use of the P126 in a vaccine program. However, we observed that a synthetic peptide, copying the 6 octapeptide repeat corresponding to the N-term of the P126, induces an antibody response to the native molecule in C57BL/6 non-responder mice. Moreover, the vaccine-P126 recombinant induced antibodies against the N-term of the molecule in rabbits while the unprocessed P126 did not.