[Preliminary study of a recombinant polyvalent vaccine of Plasmodium falciparum and its immunological activity]

A hybrid gene named HGFC coding three protective antigenic epitopes of Plasmodium falciparum and two exogenous T cell activating epitopes was designed and synthesized. A multicopy hybrid gene named HGF-CAC was also constructed. The two genes were cloned into expression vector pWR450-1 and the hybrid fusion proteins containing forgine antigens and beta-galactosidase were expressed in E. Coli. The molecular weights of the fusion proteins were 65KDa and 77KDa respectively. The expression rate was about 35% of total bacterial proteins. The fusion protein could react specifically with mouse and rabbit antibodies against antigens of Plasmodium falciparum. The rabbit immune serum against the purified fusion protein could specifically recognize the antigens of Plasmodium falciparum and effectively inhibit the in vitro development of the parasites. The inhibitory capacity of the immune sera to parasite invasion was enhanced as the amount of the sera increased and the incubation time of the sera with the parasites was prolonged. After 72h incubation at 20% concentration with the parasites, the serum suppressed the multiplication of parasite to a level of 82% and caused degeneration and death of the parasites. The results indicated that the recombinant hybrid antigen of Plasmodium falciparum has immunological activity and protectivity. It is probably a candidate malaria vaccine.