Efficiency of human Plasmodium falciparum malaria vaccine candidates in Aotus lemurinus monkeys.

The protective efficacy of several recombinant and a synthetic Plasmodium falciparum protein was assessed in Aotus monkeys. The rp41 aldolase, the 190L fragment of the MSA-1 protein and fusion 190L-CS. T3 protein containing the CS.T3 helper "universal" epitope were emulsified in Freund's adjuvants and injected 3 times in groups of 4-5 monkeys each one. The synthetic polymer Spf (66)30 also emulsified in Freund's adjuvants was injected 6 times. Control groups for both experiments were immunized with saline solution in the same adjuvant following the same schedules. Serology for malaria specific antibodies showed seroconversion in monkeys immunized with the recombinant proteins but not in those immunized with the polymer nor in the controls. Challenge was performed with the 10(5) parasites from the P. falciparum FVO isolate. Neither rp41 nor Spf(66)30 induced protection, whereas 190L induced significant delay of parasitemia. The fusion of the CS.T3 epitope to 190L significantly increased its protective capacity.