Efficacy, Safety and Immunogenicity Study of GlaxoSmithKline(GSK) Biologicals' Candidate Malaria Vaccine 257049 in the Sporozoite Challenge Model in Healthy Malaria-naïve Adults

RTS,S/AS01B administered as 0.5 mL dose at 0 and 1 months and 0.1 mL dose at 7 months for 0,1,7 M Group (delayed fractional dose group). In subjects unprotected in the first challenge, to receive a booster with a fractional dose of RTS,S/AS01B followed by rechallenge. In subjects protected in the first challenge, randomization to receive or not receive a booster with a fractional dose of RTS,S/AS01B followed by rechallenge.

RTS,S/AS01B administered as three doses of 0.5mL given one month apart (0, 1, 2 M group) in the challenge model. In subjects unprotected in the first challenge, to receive a booster with a fractional dose of RTS,S/AS01B followed by rechallenge. In subjects protected in the first challenge, randomization to receive or not receive a booster with a fractional dose of RTS,S/AS01B followed by rechallenge.

"Mosquitoes infected approximately 2-3 weeks earlier that are likely to contain sporozoites in their salivary glands will be allowed to feed on the volunteers. For each volunteer, five mosquitoes will be allowed to feed over five minutes, after which they will be dissected to confirm how many were infected, and the salivary glands scored.~The challenge is scheduled to occur approximately 21 days (3 weeks) after the last vaccination visit (Study Day 196). Volunteers who reconsent for the boost/rechallenge phase will be rechallenged with sporozoite-infected mosquitoes, scheduled to occur approximately 21 days (3 weeks) after the booster dose (Booster Phase Study Day 21)."