Structural mechanisms of HIV drug resistance.

Antiviral therapy for AIDS has focused on the discovery and design of inhibitors for two main enzyme targets of the human immunodeficiency virus type 1 (HIV)--reverse transcriptase (RT) and protease (PR). Despite several classes of promising new anti-HIV agents, the clinical emergence of drug-resistant variants of HIV has severely limited the long-term effectiveness of these drugs. Genetic analysis of resistant virus has identified a number of critical mutations in the RT and PR genes. Structural analysis of inhibitor-enzyme complexes and mutational modeling studies are leading to a better understanding of how these drug-resistance mutations exert their effects at a structural level. These insights have implications of the design of new drugs and therapeutic strategies to combat drug resistance to AIDS.