A Research Study to See if a Change in Therapy for HIV Infection Can Improve the Immune Response to Treatment

Our goal is to determine if a change in therapy to one containing Kaletra can improve the immune response in patients who have previously been immune partial responders or non-responders. We also are interested in knowing if this agent improves immune response by affecting cluster of differentiation 4 (CD4) + T cell death (apoptosis) or by further inhibiting (preventing) ongoing, low-level, viral replication to levels below detection by current viral load measurements. This will help us understand why immune responses to effective antiretroviral therapy are so different and help determine some possible guidelines for managing patients with poor immune responses. Hypothesis: Patients with poor immune responses to HAART who receive Kaletra in place of their current PI or Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs) while continuing their current 2 NRTI backbone will have improved immune response to therapy compared to patients who continue their current regimen.