Project 4 goals are to identify and characterize mutations in protease (PR) and Gag-Pol outside of PR thatcontribute to resistance development against PR inhibitors (PI). Past studies by our program have focusedon changes within PR that impart drug resistance. However, recent findings indicate that additionalmutations arise in Gag-Pol that complement drug resistance mutations within PR. These secondarymutations occur both within natural cleavage sites and other areas of Gag-Pol. These findings limit the utilityof studying resistance mutations solely within PR to direct development of new Pis and imply that nonproteasemutations must be taken into consideration. Therefore, we will investigate the Pi-directed evolutionof resistance development in both tissue culture and in sequential samples from patients undergoing PItreatment. We propose four Specific Aims to complete our goals: 1) Identify and determine the relativecontributions 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 frompatients identified in the analyses of the clinical data set provided by the Clinical Core that were resistant toselected classes of protease inhibitors and from patients that have been 'ping-ponged' during proteaseinhibitor treatment. 3) Protease mutants generated under Aims 1 and 2 will be used for selection andgeneration of new inhibitors in collaboration with Project 3 and unique PRs will also be used as targets forfragment screening analyses under Project 2. 4) In collaboration with the Structural & Protein ExpressionCore, we will perform structural studies on mutant PRs and targeted regions of Gag-Pol to establish amolecular basis for PI resistance identified in Aims 1 & 2. The proposed studies will substantially broaden thescope of our previous studies performed over the past 15 years and will provide invaluable informationrelevant to understanding and responding to resistance development of PR and Gag-Pol observed usingcurrent and future HIV drug therapies.Lay Language: Resistance to HIV drugs is a major problem world-wide. Our studies are directed atdetermining how drug resistance to HIV occurs and to use this knowledge to develop better drugs thatcontrol drug-resistant-HIV and that are more difficult for HIV resistance development.
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