Successful vaccination against intracellular pathogens, including liver-stagePlasmodium falciparum,will require induction of strong antigen-specific lymphocyte responses. The multiple epitope (ME)-thrombospon-din-related adhesion protein (TRAP) construct includes CD8+ and CD4+ cell epitopes from pre-erythrocyticP. falciparumantigens fused in-frame to the entire pre-erythrocytic antigen TRAP. Three carriers for this constructplasmid DNA and 2 recombinant nonreplicating poxviruses (modified vaccinia virus Ankara [MVA] and fowlpox strain 9 [FP9])were administered at 3-week intervals in a heterologous prime-boost combination to 29 Gambian men aged 18-45 years. Doses of DNA -TRAP, MVA -TRAP, and FP9 -TRAP were 2 mg and 1.5 X 108 and 1 X 108 plaque-forming units, respectively. DNA -TRAP was injected intramuscularly; MVA -TRAP and FP9 -TRAP were injected intradermally. There were no clinically relevant laboratory abnormalities and no severe or serious adverse events related to vaccination. DNA/MVA and FP9/MVA regimens were the most potent inducers of circulating effector cells seen to date in sub-Saharan Africa. Twelve months after the final vaccination, a single booster vaccination expanded the effector cell pool to a similar or higher magnitude than that after the primary vaccinations. These results highlight optimized combination regimens with general relevance to the development of vaccines targeting intracellular pathogens.