Clinical study to assess the efficacy and safety of a new antiretroviral drug (MPC-4326) in patients with Human immunodeficiency virus-1 (HIV-1) infection over a period of 14 days to 72 weeks.

The main purpose of this research study is to evaluate the antiretroviral (how effective the drug is at reducing the amount of HIV in the blood) activity of two different doses of MPC-4326 in HIV-1 positive participants and what, if any, side effects there may be through 14 days of dosing. This study will also evaluate the antiretroviral activity and safety of bevirimat in participants who continue treatment with bevirimat as part of combination highly active antiretroviral therapy for up to 72 weeks. We also want to know how much of the drug gets into your blood stream following oral administration. We are asking participants who will start their treatment for the first time (so called naïve (exposed to treatment for the first time) participants) and who are already on treatment (treatment experienced participants) to participate. If you choose to participate in this study and do not intend to continue MPC-4326 treatment past 14 days, you should not expect any medical benefits from taking part in this study and it is even possible that your HIV could worsen during the study. The potential benefit to society may be information gained on the safety and effectiveness of the study treatment for patients in the future. However, if you choose to participate in this study and intend to continue MPC-4326 treatment past 14 days should your viral load reduction in those first 14 days be at least two-thirds or 66.6% as compared with your viral load value at baseline, then you may have medical benefits from taking part in this study. These possible benefits include a persistent viral load reduction and an improvement in the CD4 count (a blood marker of immune system health) that may occur. As this is an experimental medication, the likelihood of these benefits occurring for you is not yet known.