v) Outlines of the study : In the proposed study, we aim at evaluating tolerability, safety, immunogenicity and efficacy of Cenv3 peptide vaccine in 112 healthy volunteers as a placebo controlled open labeled phase 1 clinical trial. Tolerability and safety parameters include clinical signs ( acute and chronic), biochemical assays ( hepatic and renal functions as well as other metabolic parameters) and hematological tests ( all blood cell parameters). Both humoral and cellular responses to the immunization protocols will be evaluated. Neutralizing capacities of specific Abs generated in response to the vaccine will also be determined after vaccination.