 The HIV vaccine to be administered during this study consists of three recombinant HIV clade B viral antigens: the envelope glycoprotein gp120 and two regulatory proteins, Nef and Tat.The antigens are formulated in a proprietary adjuvant, AS02A, comprised of two immunostimulants in an oil-in-water emulsion gp120NefTatAS02A. The vaccine and the adjuvant are manufactured and provided for the study by GlaxoSmithKline Biologicals, Rixensart, Belgium. The drugs will be given by intramuscular IM injection at a standard dose of 20 mg together with 0.5 ml of the AS02A adjuvant. 