Drug resistance may develop in HIV infected patients who take anti-HIV drugs, but most patients do well if they continue taking them. The purpose of this study is to test the effectiveness of a short, intensified course of anti-HIV drugs for controlling HIV infection in adults who have virus resistant to multiple drugs.

While an HIV infected patient is taking highly active antiretroviral therapy (HAART), drug-resistant HIV may emerge; however, it has been observed that HIV viral loads while on HAART are usually lower than baseline levels. Expansion of the T cell population during early HAART may explain this phenomenon. It is hoped that a short but aggressive HAART regimen to treatment-experienced patients who have drug-resistant virus will produce immune cells that will better control drug-resistant virus. This study will determine if a 6-month HAART regimen intensified by enfuvirtide (T-20) is effective in eliciting a stronger immune response against drug-resistant virus.

This study will last 48 weeks. All participants will receive T-20 as part of a HAART intensification regimen; HAART other than T-20 will not be provided by the study. There will be 17 study visits. Prior to beginning treatment intensification, participants will have weekly study visits for three weeks. Once treatment intensification has started, participants will be followed weekly for four weeks, then weekly for four weeks after treatment intensification, then monthly thereafter. Blood collection will occur at each visit.

Inclusion Criteria:

• HIV viral load of more than 1000 copies/ml
• On stable antiretroviral therapy
• Have multidrug resistance

Exclusion Criteria:

• Require immunomodulatory drugs