Combination of mutations in human immunodeficiency virus type 1 reverse transcriptase required for resistance to the carbocyclic nucleoside 1592U89

Abstract

The carbocyclic nucleoside 1592U89 is a selective inhibitor of the human immunodeficiency virus (HIV), targeting the reverse transcriptase (RT). In vitro selection studies were undertaken to generate resistant variants with both HIV type 1 (HIV-1) wild-type strain HIV-1 (HXB2) and 3-azido-3-deoxythymidine (AZT)resistant strain HIV-1 (RTMC) . At least two or three mutations in RT were required to produce a 10-fold reduction in susceptibility. The first RT mutation selected was at codon 184, methionine (M) to valine (V), for HIV-1 (HXB2) and HIV-1 (RTMC) , conferring two-and fivefold resistance, respectively. Two additional mutations were selected with HIV-1 (HXB2) , either leucine (L) 74 to V and lysine (K) 65 to arginine (R) (first-passage series) or L74 to V and tyrosine (Y) 115 to phenylalanine (F) (second-passage series). Cloned variants, obtained from the 1592U89 selection, were either double RT mutants 65R/184V and 74V/184V or triple RT mutant 74V/115Y/184V. Molecular clones were constructed with single, double, and triple combinations of these mutations for resistance analysis with different RT inhibitors. Each individual mutation conferred only low-level resistance (two-to fourfold) to 1592U89 in the HXB2 background. Double mutants containing the 184V mutation and triple mutants showed slightly greater levels of resistance to 1592U89 (7-to 11-fold). Some of the 1592U89-resistant variants were cross-resistant with 2,3-dideoxycytidine, 2,3-dideoxyinosine, and (؊)-2-deoxy-3-thiacytidine, but none were resistant to 2,3-didehydro-3-deoxythymidine or AZT.

Selection of a rare resistance profile in an HIV-1-infected patient exhibiting a failure to an antiretroviral regimen including tenofovir DF

“…Conversely, reduced activity has been observed with the K65R mutation, selected by tenofovir in vitro, resulting in a 3-to 4-fold decrease of tenofovir susceptibility. The K65R mutation has also been selected by zalcitabine, didanosine, abacavir and stavudine in vitro but with a rare occurrence in vivo (<2%) (De Antoni et al, 1997;Garcia-Lerma et al, 2003;Gu et al, 1994;Tisdale et al, 1997;Winston et al, 2002Winston et al, , 2004.…”

Antiretroviral drug resistance in HIV-1

“…In vitro resistance to abacavir was associated with Lys65Arg, Leu74Val, Tyr115Phe, and Met184Val [38]. Singly, these mutations increase IC 50 to the drug only minimally, while a combination of three of these mutations confers a 10-fold increase.…”

Nucleoside and nucleotide inhibitors of HIV-1 replication

“…Mutation at position 74 (mostly L74V) is frequently found in patients receiving ddI mono-therapy [48,68,75,76] and also occurs during ABC mono-therapy [56,74]. In the former case, L74V is associated with other mutations (mainly M184V) [77]. The L74V mutation causes virologic failure primarily in patients receiving ddI [75,76,78], but not ABC mono-therapy and prevents antiviral activity when ddI is used for intensification [79].…”

“…Mutation K65R emerges after mono-therapy with ddI [48,80], ddC [80,81] or ABC [74], and during tenofovir intensification [60]. K65R is also frequently selected in cell culture by ABC [77], tenofovir [60] and d4T [82], and its incidence increased recently, mainly in patients receiving tri-therapies excluding AZT [83]. K65R confers intermediate resistance levels to ddI [84], ddC [80,84,85], 3TC [84][85][86], d4T [82], tenofovir [60,87] and ABC when associated with other mutations [77] (fig.…”