This is a pilot study designed to determine a dose and schedule of Tucaresol that can be administered to HIV-1 infected subjects on HAART (highly active antiretroviral therapy) with viral suppression without occurrence of significant adverse events and that results in significant changes in cell mediated immunity.

Inclusion Criteria:

• Currently on licensed triple combination therapy, which is defined as two nucleoside analogues (2 NRTI) (excluding Abacavir) and a protease inhibitor (PI) (including boosted PI regimens) or non nucleoside reverse transcriptase inhibitor (NNRTI).
• Must be on the same treatment for at least 3 months prior to study without plans to alter therapy for the next 3 months.

Plasma HIV-1 RNA (ribonucleic acid)< 50 copies/mL at screening with a documented history of continuous suppression defined as: the last two readings < 50 copies/mL for a period of at least 3 months prior to screening.

• Documented CD4+ lymphocyte cell count =350 cells/ml at screening with at least one reading =350 cells/mL in the preceding 3 months and CD4 nadir >200 cells/ml.

HBsAg (human hepatitis B Virus surface antigen) and HCV-Ab (human hepatitis C Virus antibody) negative.

Exclusion Criteria:

• History of hyperimmune or allergic reactions to drug treatment within 3 months prior to study.