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In Vitro Selection and Analysis of Human Immunodeficiency Virus Type 1 Resistant to Derivatives of -2',3'-Didehydro-2',3'-Dideoxy-5-Fluorocytidine

Division of Infectious Diseases, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
Antimicrobial Agents and Chemotherapy (Impact Factor: 4.45). 10/2005; 49(9):3930-2. DOI: 10.1128/AAC.49.9.3930-3932.2005
Source: PubMed

ABSTRACT Serial passage of human immunodeficiency virus type 1 in MT-2 cells in increasing concentrations of the d- and l-enantiomers of beta-2',3'-didehydro-2',3'-dideoxy-5-fluorocytidine (d4FC) resulted in the selection of viral variants with reverse transcriptase substitutions M184I or M184V for l-d4FC and I63L, K65R, K70N, K70E, or R172K for d-d4FC. Phenotypic analysis of site-directed mutants defined the role of these mutations in reducing susceptibility to l- or d-d4FC.

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Available from: Raymond F Schinazi, Sep 02, 2015
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    • "L-β-2′,3′-didehydro-2′,3′-dideoxy-5-fluorocytidine (Elvucitabine, L-d4TC) (Figure 8) is an L-cytidine analog under investigation in phase I/II clinical trials that is more potent than 3TC and that shows no mitochondrial toxicity [75] and an interesting protecting effect on the mitochondrial toxicity due to other NRTIs [76]. L-d4TC resistance profile shows that it selects for M14V RT mutants [77] and has a 10-fold potency reduction on K65R mutant strains [78]. "
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    ABSTRACT: The K65R mutation in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is selected in vitro by many D-nucleoside analog RT inhibitors (NRTI) but has been rarely detected in treated patients. In recent clinical trials, the K65R mutation has emerged frequently in patients experiencing virologic failure on antiretroviral combinations that do not include 3'-azidothymidine (AZT). The reason for this change is uncertain. To gain insight, we examined trends in the frequency of K65R in a large genotype database, the association of K65R with thymidine analog mutations (TAMs) and other NRTI mutations, and the viral susceptibility profile of HIV-1 with K65R alone and in combination with TAMs. Among >60,000 clinical samples submitted for genotype analysis that contained one or more NRTI resistance mutations, the frequency of K65R increased from 0.4% in 1998 to 3.6% in 2003. Among samples with K65R, a strong negative association was evident with the TAMs M41L, D67N, L210W, T215Y/F, and K219Q/E (P<0.005) but not with other NRTI mutations, including the Q151M complex. This suggested that K65R and TAMs are antagonistic. To test this possibility, we generated recombinant HIV-1 encoding K65R in two different TAM backgrounds: M41L/L210W/T215Y and D67N/K70R/T215F/K219Q. K65R reduced AZT resistance from >50-fold to <2.5-fold in both backgrounds. In addition, TAMs antagonized the phenotypic effect of K65R, reducing resistance to tenofovir, abacavir, 2',3'-dideoxycytidine, dideoxyinosine, and stavudine. In conclusion, K65R and TAMs exhibit bidirectional phenotypic antagonism. This antagonism likely explains the negative association of these mutations in genotype databases, the rare emergence of K65R with antiretroviral therapies that contain AZT, and its more frequent emergence with combinations that exclude AZT.
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