DNA immunization by Plasmodium falciparum liver-stage antigen 3 induces protection against Plasmodium yoelii sporozoite challenge

DNA-based immunization of mice by Plasmodium falciparum liver-stage antigen 3 (PfLSA3), a novel highly conserved P. falciparum preerythrocytic antigen , was evaluated. Animals developed a dominant Th1 immune response thigh gam ma interferon T-cell responses and predominance of immunoglobulin G2a) to e ach of three recombinant proteins spanning the molecule. We have exploited the immunological cross-reactivity of PfLSA3 with its putative homologue on sporozoites of the rodent parasite Plasmodium yoelii, and we show for the first time that responses induced by PfLSA3 in mice significantly protect a gainst a heterologous challenge by P. yoelii sporozoites. These results sup port a significant effect of DNA-induced immune responses on preerythrocyti c stages.