Safety and Preliminary Efficacy of the Malaria Vaccine Candidates Falciparum Merozoite Protein-1 (FMP1) and SmithKlineBeecham (SKBB) Candidate Malaria Vaccine RTS,S

The vaccine antigen FMP1 consists of a recombinant histidine-tagged (His6) fusion protein expressed in E. coli. The lyophilized pellet contained per vaccine vial 62.5 μg merozoite surface protein-142 (MSP-142) with 3.1% lactose as cryoprotectant in each 3 ml monodose vial. The pellet was reconstituted with AS02.

The vaccine antigen RTS,S, is a recombinant subunit vaccine produced in, and purified from yeast cells. The final lyophilized pellet contained 62.5 μg RTS,S with 3.15% lactose as cryoprotectant per 3 ml monodose vial. The pellet was reconstituted in AS02 and each 0.5 ml dose contained 50 μg RTS,S.

AS02 adjuvant contains 50 μg monophosphoryl lipid A (MPL) and 50 μg Quillaja saponaria 21 (QS-21), 250 μl of SB62 (oil/water emulsion) in phosphate buffered saline (PBS) per volume of 0.5 ml.

Experimental challenge homologous strain of P.falciparum sporozoites. Mosquitoes infected with malaria approximately 17 to 19 days earlier and that contained sporozoites in their salivary glands. For each volunteer, five mosquitoes were allowed to feed over five minutes, after which they were dissected to confirm how many were infected, and the salivary glands scored.