Long-lasting protective immunity against rodent malaria parasite infectionat the blood stage by recombinant BCG secreting merozoite surface protein-1

Previously, we constructed a recombinant live BCG (rBCG) secreting a 15 kDa C-terminal region of MSP-1 from Plasmodium yoelii (MSP-1(15)) and succeede d in the induction of more efficient protective immunity against parasite i nfection than observed with artificial adjuvants (Matsumoto S, Yukitake H, Kanbara H, Yamada T. Recombinant Mycobacterium bovis bacillus Calmette-Guer in secreting merozoite surface protein 1 (MSP-1) induces protection against rodent malaria parasite infection depending on MSP-1-stimulated interferon gamma and parasite-specific antibodies. J Exp Med 1998;188:845-54 [1]). In this study, we examined the endurance of the protective effects. The prote ctive effect generated by rBCGMSP-1(15) was observed even 9 months after fi nal immunization, whereas the effects of immunization by MSP-1(15) together with incomplete Freund adjuvant (IFA) were found to last only 4 months. (C ) 1999 Elsevier Science Ltd. All rights reserved.