The purpose of this study is to see if children and young adults with better immune systems before starting highly active antiretroviral therapy (HAART) do better than those who have weaker immune systems before starting HAART.

HIV infection weakens the immune system's ability to fight other infections and diseases. HAART is a type of anti-HIV therapy shown to improve the immune system of adults. However, not all patients show the same amount of improvement with HAART. Doctors believe that results may depend on how strong a patient's immune system is before starting HAART. Long-term effects of HAART in children and young adults have not yet been studied.

Recent adult clinical trials involving combination HAART, including a protease inhibitor (PI), have demonstrated improvements in somatic immune system functioning. [AS PER AMENDMENT 2/27/01: More recently, similar success has been demonstrated with a PI-sparing regimen, zidovudine, lamivudine, and efavirenz.] Not all individuals, however, experience the same level of immune reconstitution, and oftentimes any improvement is short-lived. Adolescent patients may have a greater potential for immune restoration because of residual thymic tissue and therefore may experience greater long-term virus-free states as compared to adult patients. This study examines the duration of virologic efficacy HAART has on the adolescent HIV-positive population.

Patients begin study by initiating a HAART regimen of a minimum of 3 drugs, at least 1 of which must be a PI [AS PER AMENDMENT 2/27/01: or efavirenz (EFV)]. A variety of drug combinations are used; therefore, patients are grouped according to the classes of drugs in their respective regimen (e.g., 2 nucleoside reverse transcriptase inhibitors [NRTIs] plus 1 PI; 2 NRTIs plus 2 PIs; 1 or 2 NRTIs plus 1 PI plus 1 nonnucleoside reverse transcriptase inhibitor [NNRTI] [AS PER AMENDMENT 2/27/01: ; and 2 NRTIs plus EFV]). At the time of HAART initiation, patients undergo immunologic and virologic assessments in order to determine baseline values. Then, to determine the virologic success or failure of HAART, HIV-1 RNA measurements are taken and compared to initial baseline values. Virologic success equals undetectable HIV-1 RNA at Week 12 [AS PER AMENDMENT 2/27/01: and confirmed at Week 16] or a significant (greater than 1 log) decrease in HIV-1 RNA from baseline to Week 12 [AS PER AMENDMENT 2/27/01: and confirmed undetectable HIV-1 RNA before the next scheduled visit (Week 24)]. Patients are followed for a minimum of 3 years of maintained viral suppression or until they have demonstrated virologic failure. From these values, any correlation that may exist between HIV-1 RNA values and HAART can be deduced. Patients with virologic failure on the initial HAART regimen may be allowed to change to a second HAART regimen. [AS PER AMENDMENT 2/27/01: Patients with virologic success on the second HAART regimen are followed for a minimum of 3 years.] Patients with virologic failure on the second HAART regimen or who voluntarily discontinue HAART are followed using an abbreviated schedule for 3 years.

Inclusion Criteria

Children may be eligible for this study if they:

• Are HIV-positive.
• Are between 8 and 22 years old (consent of parent or guardian required if under 18).
• Have detectable levels of HIV in the blood within 30 days prior to study entry.
• Expect to be on the study for at least 1 year. (This study has been changed by adding this requirement.)
• Are pregnant and are not taking didanosine/stavudine (ddI/d4T) or EFV as part of their HAART regimen. (This study has been changed so that pregnant patients may be eligible if they are not taking ddI/d4T or EFV.)

Exclusion Criteria

Children will not be eligible for this study if they:

• Are taking HAART or more than 1 anti-HIV drug.
• Were infected with HIV before birth, at the time of delivery, or by a blood transfusion during birth.
• Have taken part in the study before.
• Have not responded well to HAART in the past.
• Have taken drugs to boost the immune system such as HIV vaccines, IVIG, or cytokine therapy.
• Have AIDS-related (opportunistic) infection at the time of screening. (This study has been changed so that patients with an AIDS-related infection are ineligible.)
• Are pregnant and are taking ddI/d4T or EFV as part of their HAART regimen. (This study has been changed so that pregnant patients are ineligible if they are taking ddI/d4T or EFV.)