STRUCTURE-BASED MECHANISMS FOR RESISTANCE TO PROTEASE INHIBITORS

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Project 4 goals are to identify and characterize mutations in protease (PR) and Gag-Pol outside of PR that contribute to resistance development against PR inhibitors (PI). Past studies by our program have focused on changes within PR that impart drug resistance. However, recent findings indicate that additional mutations arise in Gag-Pol that complement drug resistance mutations within PR. These secondary mutations occur both within natural cleavage sites and other areas of Gag-Pol. These findings limit the utility of studying resistance mutations solely within PR to direct development of new Pis and imply that nonprotease mutations must be taken into consideration. Therefore, we will investigate the Pi-directed evolution of resistance development in both tissue culture and in sequential samples from patients undergoing PI treatment. We propose four Specific Aims to complete our goals: 1) Identify and determine the relative contributions to drug resistance of mutations in PR and Gag-Pol outside of PR that arise under extreme "ping-pong" protease inhibitor selection in tissue culture. 2) Characterize sequential virus samples from patients identified in the analyses of the clinical data set provided by the Clinical Core that were resistant to selected classes of protease inhibitors and from patients that have been "ping-ponged" during protease inhibitor treatment. 3) Protease mutants generated under Aims 1 and 2 will be used for selection and generation of new inhibitors in collaboration with Project 3 and unique PRs will also be used as targets for fragment screening analyses under Project 2. 4) In collaboration with the Structural & Protein Expression Core, we will perform structural studies on mutant PRs and targeted regions of Gag-Pol to establish a molecular basis for PI resistance identified in Aims 1 & 2. The proposed studies will substantially broaden the scope of our previous studies performed over the past 15 years and will provide invaluable information relevant to understanding and responding to resistance development of PR and Gag-Pol observed using current and future HIV drug therapies. Lay Language: Resistance to HIV drugs is a major problem world-wide. Our studies are directed at determining how drug resistance to HIV occurs and to use this knowledge to develop better drugs that control drug-resistant-HIV and that are more difficult for HIV resistance development.