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In vitro selection of mutations in the human immunodeficiency virus type 1 reverse transcriptase that decrease
H Z Bazmi1, J L Hammond, S C Cavalcanti
1Department of Infectious Diseases and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
Antimicrobial Agents and Chemotherapy
|June 20, 2000
Summary
Human immunodeficiency virus type 1 (HIV-1) resistance to (-)-beta-D-dioxolane-guanosine (DXG) was studied. Mutations K65R and L74V were identified, impacting resistance to other drugs and potentially reversing AZT resistance.
Area of Science:
- Virology
- Molecular Biology
- Drug Resistance
Background:
- Nucleoside analog reverse transcriptase inhibitors (NRTIs) are crucial in HIV-1 therapy.
- Development of drug resistance is a major challenge in HIV-1 treatment.
- (-)-beta-D-dioxolane-guanosine (DXG) is a potent HIV-1 reverse transcriptase (RT) inhibitor.
Purpose of the Study:
- To investigate the mechanisms of HIV-1 resistance to DXG.
- To identify specific mutations conferring DXG resistance.
- To assess the cross-resistance and impact of these mutations on other antiretroviral drugs.
Main Methods:
- Serial passage of HIV-1(LAI) in the presence of increasing DXG concentrations.
- Cloning and DNA sequencing of the HIV-1 RT gene from resistant isolates.
- Site-specific mutagenesis to confirm the role of identified mutations.
Main Results:
- Two independent experiments yielded DXG-resistant HIV-1 isolates with 7.3- and 12.2-fold increased EC(50)s.
- The K65R mutation was identified in the first isolate and conferred cross-resistance to several NRTIs but reversed AZT resistance.
- The L74V mutation was identified in the second isolate and also decreased AZT resistance.
Conclusions:
- DXG and certain 2',3'-dideoxy compounds select for overlapping resistance mutations.
- DXG and ddI may not be optimal for combination therapy due to shared resistance pathways.
- Combination therapy with AZT and DXG or its prodrug warrants further investigation due to potential synergistic effects in suppressing AZT resistance.