Recombinant chimeric proteins generated from conserved regions of Plasmodium falciparum merozoite surface protein 2 generate antiparasite humoral responses in mice

The merozoite surface protein 2 of P. falciparum is highly polymorphic in n ature, but has regions of almost complete conservation at its N- and C-term ini. We produced a chimeric recombinant protein comprising these regions on ly (hereafter termed NC). Mice immunized with the NC antigen produce antibo dies at levels comparable to those immunized with 1624, a full-length recom binant protein representing MSP2 from P. falciparum. Antisera raised agains t NC recognized P. falciparum schizonts by IFA and a P. falciparum protein of M-r 45 kDa by Western blot. However, antibody specificities were observe d to differ between anti-NC and anti-1624 sera, and this resulted in differ ences in parasite recognition, despite similar levels of antibodies having been produced. The response to the NC antigen was also shown to be restrict ed in some mice (H2-d), but this was overcome by including appropriate T-ce ll help, which was accomplished by creating recombinant protein chimeras th at contained NC and T-helper epitopes from Tetanus toxoid, or MSP1(19) from P. berghei.