The goals of this application are to understand to what extent replication fitness influences the emergence of HIV variants resistant to non-nucleoside reverse transcriptase inhibitors (NNRTIs), and to delineate the underlying biochemical mechanisms for how drug resistance mutations interact to influence replication fitness. NNRTI-resistant variants of HIV, usually cross-resistant to other NNRTIs, develop rapidly if viral replication is not suppressed. We have shown that HIV replication fitness, as measured in cell culture, is reduced in NNRTI-resistant mutants that are infrequent clinically, even though they confer higher levels of resistance than the most common mutant, K103N. These poorly replicating mutants also reduce RNase H cleavage by reverse transcriptase. Two mutants, G190S and A, also reduce priming from tRNA(Lys,3), raising the question of whether defects in RNA priming also contribute to the reduced fitness of NNRTI- resistant mutants. We also have shown that the nucleoside (nRTI) resistance mutation L74V compensates for the reduced fitness of K103N+L100I, but does not improve its reduced RNase H cleavage rates. Published studies by others have shown that L74V reduces RNA priming. We therefore propose that L74V can compensate for the reduced RNase H activity of poorly replicating, highly NNRTI-resistant variants by improving steps in reverse transcription, such as strand transfer and strand displacement synthesis, that compensate for RNase H cleavage defects. We postulate that selection for highly NNRTI-resistant variants that have improved fitness from compensatory nRTI resistance mutations can lead to early virologic failure. These studies have important implications for the more rational design of nRTI-NNRTI combination regimens. During the next funding period, we plan to: 1. Evaluate the association of nRTI and NNRTI resistance mutations in clinical samples. 2. Determine the effects of nRTI resistance mutations on the replication fitness and drug resistance of NNRTI-resistant mutants. 3. Characterize the biochemical basis for how L74V improves the fitness of NNRTI-resistant variants. Relevance: The proposed studies will evaluate what factors lead to the development of drug resistant strains of HIV, how changes in reverse transcriptase function affect replication of HIV, and whether combinations of drugs can be chosen to influence which drug resistant strains develop.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI041387-12
Application #
8054996
Study Section
AIDS Discovery and Development of Therapeutics Study Section (ADDT)
Program Officer
Ussery, Michael A
Project Start
1998-04-01
Project End
2013-04-30
Budget Start
2011-05-01
Budget End
2013-04-30
Support Year
12
Fiscal Year
2011
Total Cost
$370,170
Indirect Cost
Name
University of Rochester
Department
Internal Medicine/Medicine
Type
Schools of Dentistry
DUNS #
041294109
City
Rochester
State
NY
Country
United States
Zip Code
14627
Wang, Jiong; Li, Dongge; Bambara, Robert A et al. (2013) Reverse transcriptase backbone can alter the polymerization and RNase activities of non-nucleoside reverse transcriptase mutants K101E+G190S. J Gen Virol 94:2297-308
Wang, Jiong; Li, Dongge; Bambara, Robert A et al. (2013) L74V increases the reverse transcriptase content of HIV-1 virions with non-nucleoside reverse transcriptase drug-resistant mutations L100I+K103N and K101E+G190S, which results in increased fitness. J Gen Virol 94:1597-607
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Wang, Jiong; Zhang, Gang; Bambara, Robert A et al. (2011) Nonnucleoside reverse transcriptase inhibitor-resistant HIV is stimulated by efavirenz during early stages of infection. J Virol 85:10861-73
Ma, Jingming; Dykes, Carrie; Wu, Tao et al. (2010) vFitness: a web-based computing tool for improving estimation of in vitro HIV-1 fitness experiments. BMC Bioinformatics 11:261
Wang, Jiong; Bambara, Robert A; Demeter, Lisa M et al. (2010) Reduced fitness in cell culture of HIV-1 with nonnucleoside reverse transcriptase inhibitor-resistant mutations correlates with relative levels of reverse transcriptase content and RNase H activity in virions. J Virol 84:9377-89
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Wang, J; Liang, H; Bacheler, L et al. (2010) The non-nucleoside reverse transcriptase inhibitor efavirenz stimulates replication of human immunodeficiency virus type 1 harboring certain non-nucleoside resistance mutations. Virology 402:228-37
von Wyl, Viktor; Ehteshami, Maryam; Demeter, Lisa M et al. (2010) HIV-1 reverse transcriptase connection domain mutations: dynamics of emergence and implications for success of combination antiretroviral therapy. Clin Infect Dis 51:620-8

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