Inclusion Criteria:

• Twelve to 24 years of age, regardless of the mode of transmission.
• Subjects must have been on a stable HAART regimen containing at least one PI and two NRTIs and no NNRTI for at least 3 months and be willing to continue the PI-containing regimen throughout the study period.
• Acceptable viral load defined as at least three plasma HIV-1 RNA levels ≤ 400 copies/ml within 12 months of study entry and no plasma HIV-1 RNA levels > 400 copies/ml within 6 months of entry date employing any clinically available viral load assay.
• Pre entry plasma HIV-1 RNA level <200 copies/ml by ultra-sensitive assay (Roche 1.5) within 30 days of study entry, performed in an assigned PACTG core virology laboratory.
• CD4+ T cell count >350 cells/microL within 30 days of study entry.
• Ability of subject and parent or legal guardian (when appropriate) to give written informed assent/consent and permission respectively.

• Subjects currently enrolled in ATN 015 Version 2.0 are eligible as follows:

  • Subjects randomized to standard continuous therapy (control arm). These subjects are eligible to be enrolled in ATN 015 Version 3.0 as new subjects if they meet the entry criteria for ATN Version 3.0. If eligible, they will be followed for the full 48 weeks.
  • Subjects randomized to short cycle therapy (experimental arm). These subjects are eligible to rollover to ATN 015 Version 3.0 and continue on SCT if they have not met a study endpoint. These subjects may not have a viral load value that meets a study endpoint (viz. a confirmed viral load of >400 copies/ml) and will continue on the intensive monitoring until they have completed 24 weeks when they will enter the less intensive 24 week phase of the study.
• Female subjects must be non-pregnant and willing to remain on effective contraception for the duration of the study. (Examples of acceptable forms of birth control include but are not limited to any form of hormonal contraception along with a barrier method, double barrier method, tubal ligation, or abstinence if it is the choice of the subject.)

Exclusion Criteria:

• On a HAART regimen containing an NNRTI or a HAART regimen with Abacavir (including Trizivir®).
• On any prohibited medication at the time of screening. Subjects with underlying reactive airway disease who are on either inhaled or brief, intermittent systemic steroids can be considered but their status must be reviewed with the protocol chair or vice chair through the standard ATN protocol query process.
• Active HIV-related opportunistic infection or any malignancy at the time of screening. (Female subjects who have been treated adequately for cervical dysplasia or CIN are eligible for study unless they are on systemic immunosuppressive therapy).
• Current treatment for known or suspected active serious bacterial infection.
• Pregnancy.
• Any laboratory abnormalities Grade 3 or greater as defined in Appendix III at the time of screening.
• Subjects receiving pharmacological treatment for elevated cholesterol and triglyceride levels.

If a candidate fails the eligibility criteria (inclusion or exclusion), she or he may be screened again for eligibility after a period of 30 days.