Study of the HIV gp120/NefTat/AS02A Vaccine to Treat Individuals With Chronic HIV-1 Infection on Highly Active Antiretroviral Therapy (HAART)

Inclusion Criteria: The study will include subjects who meet all of the following criteria: * Male or female, between 18 to 60 years of age at the time of the first vaccination * Informed consent signed prior to all study procedures * No evidence of acute HIV seroconversion in the 12 months prior to the initiation of antiretroviral therapy * Receiving a potent antiretroviral drug regimen for a minimum of 12 consecutive months prior to screening with no interruption of therapy for \> 2 weeks. A potent antiretroviral drug regimen is defined as any of the following: \*two nucleoside reverse transcriptase inhibitors with either a protease inhibitor or a non-nucleoside reverse transcriptase inhibitor; \*a boosted protease inhibitor with either one or two nucleoside reverse transcriptase inhibitors or a non-nucleoside reverse transcriptase inhibitor. * Documented suppressed HIV-1 RNA. Subjects must have plasma HIV-1 RNA values \<50 copies/ml on at least two measurements during the 6 months prior to the study entry. * CD4+ T cell count \>400 cells/mm3 within 45 days of the first vaccination * CD4 count \>200 cells/mm3 at all times * Laboratory values within 45 days prior to the first vaccination that meet the following criteria: * Hemoglobin \>9.0 g/dL; * Absolute neutrophil count ≥ 1000/mm3; * Platelet count ≥ 75,000/mm3; * Prothrombin time (PT) \< 1.2 x upper limit of normal (ULN) and partial thromboplastin time (PTT) \< 1.5 x ULN; * Total serum creatinine \< 1.3 x ULN; * Total serum bilirubin \< 2.0 x ULN; * Alkaline phosphatase, AST (SGOT) and ALT (SGPT) \< 1.5 x ULN. * Negative serologic test for HBsAg * Negative serologic test for antibodies to HCV or negative HCV PCR if anti-HCV antibodies are positive. * Female patient of childbearing potential must: * Have a negative urine pregnancy test (sensitive to 25 IU HCG) immediately prior to vaccination; * Have no intention of conceiving during the entire study period; * Agree to use an effective method of birth control during the entire study period. Effective methods of birth control include: 1. Condoms (male or female) with or without spermicidal agent. Condoms are recommended because their appropriate use is the only contraception method effective for preventing HIV transmission; 2. Diaphragm or cervical cap with spermicide; 3. Intrauterine device (IUD). An IUD is an adequate method of birth control, but increases the risk of pelvic inflammatory disease; 4. An FDA-approved oral contraceptive, provided there is no interaction with the woman's current antiretroviral therapy or other medications; * If participating in sexual activity that could lead to pregnancy, the male subject or his partner must also use contraception. Exclusion Criteria: * HIV-1 RNA \> 50 copies/mL within 6 months of screening. * Received antiretroviral therapy within 12 months of known HIV-1 seroconversion. * History of clinically significant cardiac, pulmonary, gastrointestinal, hepatic, renal, pancreatic, or neurological disease * Recent (\<24 hours) febrile illness on the day of vaccination (temperature \>101 degrees F, oral) * History of CD4 count \<200 cells/mm3. * Female subject who is pregnant or nursing a child * Received any immune globulin or blood products within 3 months prior to vaccination or plans to receive such products during the study * Received any live vaccine within 30 days prior to study vaccination or any inactivated vaccine within 14 days prior to study vaccination * Previously participated in any HIV vaccine clinical trial (unless it is documented that the subject received only placebo) * History of any AIDS defining illness * Any change in antiretroviral drug regimen within 12 weeks prior to screening * Use of any immunomodulatory agents within 30 days prior to study enrollment or planned use during the trial * Active drug or alcohol use or dependence that, in the opinion of the sponsor, would interfere with adherence to study requirements. * Any condition or history of illness which, in the opinion of the investigator, might interfere with the evaluation of the study objectives * Subject has a history of anaphylaxis to any vaccine * Subject has a history of allergy to any adjuvant component * Subject is taking any of the following medications: systemic steroids (inhaled or nasal steroid therapy is permitted), interleukins, systemic interferons (e.g. local injection of interferon alpha for treatment of HPV is permitted) or systemic chemotherapy