The purpose of this study is to examine how the immune systems of HIV-infected patients react to 2 anti-HIV drug combinations.

Patients are randomized to two study arms for at least 48 weeks of treatment. Arm A receives SQV SGC plus RTV plus two NRTIs of choice. Arm B receives EFV plus two NRTIs of choice. NRTIs approved for study use are stavudine (d4T), didanosine (ddI), zidovudine (AZT), lamivudine (3TC), Combivir, and zalcitabine (ddC). Abacavir is excluded. The following immunology variables and HIV-1 viral characteristics will be evaluated during study visits: CD4 and CD8 cell counts; naive and memory T-cells; T-cell activation markers (HLA-DR and CD38); T-cells expressing T helper 1- (TH1-) and T helper 2- (TH2-) associated intracytoplasmic cytokines; anti-CD3 T-cell activation responses; T-cell receptor V Beta repertoire; cytotoxic T-lymphocyte (CTL) activity levels; lymph node histology (optional); HIV-1 qualitative microcultures and viral phenotyping for non-syncytium-inducing (NSI) and syncytium-inducing (SI) viral isolates. Laboratory determinations, adverse effects, neurological exams (including mental status evaluations), and lipodystrophy parameters (including fasting lipid profile and physical parameters) also are evaluated.

Inclusion Criteria

Patients may be eligible for this study if they:

• Are HIV-positive.
• Have a viral load of at least 5,000 copies/ml and a CD4 cell count greater than 75 cells/mm3.
• Are at least 16 (need consent of parent or guardian if under 18).
• Are able to complete the study.

Exclusion Criteria

Patients will not be eligible for this study if they:

• Have ever taken anti-HIV medications.
• Are pregnant or breast-feeding.