HIV protease

Class

Protease inhibitor (boosted)

HIV protease is an enzyme encoded by the virus itself. During the late stage of the HIV replication cycle, the virus produces long chains of protein, called polyproteins, from a single set of genetic instructions. These chains are inactive until HIV protease cuts them into individual functional proteins, including the structural and enzymatic components needed to assemble new, infectious virus particles. Protease inhibitors bind to the active site of this enzyme and block that cutting step. Without it, newly budded viral particles remain immature and non-infectious, even though they still form and leave the host cell. This mechanism is central to combination antiretroviral therapy for HIV infection, where protease inhibitors are typically paired with other classes acting at different steps of the viral life cycle to reduce the chance that the virus develops resistance. Many protease inhibitors are given together with a low dose of a second small molecule that itself has little antiviral activity but slows the metabolism of the protease inhibitor, a strategy known as pharmacologic boosting, which raises and sustains blood levels of the primary drug.