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An in vivo mutation from leucine to tryptophan at position 210 in human immunodeficiency virus type 1 reverse transcriptase contributes to high-level resistance to 3'-azido-3'-deoxythymidine.

ABSTRACT: Sequencing of the reverse transcriptase (RT) region of 26 human immunodeficiency virus type 1 (HIV-1) isolates from eight patients treated with 3'-azido-3'-deoxythymidine (AZT) revealed a mutation at codon 210 from TTG (leucine) to TGG (tryptophan) exclusively in association with resistance to AZT. The mutation Trp-210 was observed in 15 of the 20 isolates phenotypically resistant to AZT, being more commonly observed than resistance-associated mutations at codons 67, 70, and 219. Trp-210 was never observed before the emergence of resistance-associated mutations Leu-41 and Tyr-215, and in a sequential series of five isolates from one patient the order of emergence of mutations was found to be Tyr-215, Leu-41, and then Trp-210. Trp-210 was also found in association with the Leu-41, Asn-67, Arg-70, and Tyr-215 resistance genotype. To define the role of Trp-210 in AZT resistance, molecular HIV-1 clones were constructed with various combinations of RT mutations at codons 41, 67, 70, 210, and 215 and tested for susceptibility to AZT. In clones with polymerase genes derived either from HXB2-D or clinical isolates, Trp-210 alone did not increase AZT resistance, whereas in conjunction with Leu-41 and Tyr-215, Trp-210 contributed to high-level resistance (50% inhibitory concentration of >1 microM). In HXB2-D, Trp-210 with Tyr-215 generated a virus with resistance comparable to one with Leu-41, Tyr-215, and Trp-210. Inserting Trp-210 into the genetic context of mutations at codons 41, 67, 70, and 215 further enhanced resistance from a 50% inhibitory concentration of 1.44 microM to 8.41 microM. Molecular modeling of the tertiary structure of HIV-1 RT revealed that the distance between the side chains of Trp-210 (in helix alphaF) and Tyr-215 (in strand beta11a) approximated 4 A (1 A = 0.1 nm), sufficiently close to result in significant energetic interaction between these two aromatic side chains. In conclusion, Trp-210 contributes significantly to phenotypic AZT resistance of HIV-1 by augmenting resistance at least three- to sixfold in the context of two resistant genotypes, and its effect may require an interaction with an aromatic amino acid at position 215.

SUBMITTER: Hooker DJ

PROVIDER: S-EPMC190874 | biostudies-other | 1996 Nov

REPOSITORIES: biostudies-other

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An in vivo mutation from leucine to tryptophan at position 210 in human immunodeficiency virus type 1 reverse transcriptase contributes to high-level resistance to 3'-azido-3'-deoxythymidine.

Hooker D J DJ Tachedjian G G Solomon A E AE Gurusinghe A D AD Land S S Birch C C Anderson J L JL Roy B M BM Arnold E E Deacon N J NJ

Journal of virology 19961101 11

Sequencing of the reverse transcriptase (RT) region of 26 human immunodeficiency virus type 1 (HIV-1) isolates from eight patients treated with 3'-azido-3'-deoxythymidine (AZT) revealed a mutation at codon 210 from TTG (leucine) to TGG (tryptophan) exclusively in association with resistance to AZT. The mutation Trp-210 was observed in 15 of the 20 isolates phenotypically resistant to AZT, being more commonly observed than resistance-associated mutations at codons 67, 70, and 219. Trp-210 was nev ...[more]

PMID: 8892925

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Project description:The development of antiviral drug resistance is an important problem in the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Potent antiretroviral therapy is currently used for treatment, and typically consists of at least two reverse transcriptase (RT) inhibitors. We have previously reported that both drugs and drug-resistant RT mutants can increase virus mutation frequencies. To further assess the contributions of nucleoside RT inhibitors (NRTIs), nonnucleoside RT inhibitors (NNRTIs), and drug-resistant RTs to HIV mutagenesis, a new high-throughput assay system was developed. This assay system was designed to specifically detect frameshift mutations in the luciferase gene in a single virus replication cycle. New drug-resistant RTs were identified that significantly altered virus mutation frequencies. Consistent with our previous observations of NRTIs, abacavir, stavudine, and zalcitabine increased HIV-1 mutation frequencies, supporting the general hypothesis that the NRTIs currently used in antiviral drug therapy increase virus mutation frequencies. Interestingly, similar observations were made with NNRTIs. This is the first report to show that NNRTIs can influence virus mutation frequencies. NNRTI combinations, NRTI-NNRTI combinations, and combinations of drug and drug-resistant RTs led to significant changes in the virus mutation frequencies compared to virus replication of drug-resistant virus in the absence of drug or wild-type virus in the presence of drug. This indicates that combinations of RT drugs or drugs and drug-resistant virus created during the evolution of drug resistance can act together to increase HIV-1 mutation frequencies, which would have important implications for drug therapy regimens. Finally, the influence of drug-resistant RT mutants from CRF01_AE viruses on HIV-1 mutation frequencies was analyzed and it was found that only a highly drug resistant RT led to altered virus mutation frequencies. The results further suggest that high-level drug-resistant RT can significantly influence virus mutation frequencies. A structural model that explains the mutation frequency data is discussed.

Dataset Information

An in vivo mutation from leucine to tryptophan at position 210 in human immunodeficiency virus type 1 reverse transcriptase contributes to high-level resistance to 3'-azido-3'-deoxythymidine.

Publications

An in vivo mutation from leucine to tryptophan at position 210 in human immunodeficiency virus type 1 reverse transcriptase contributes to high-level resistance to 3'-azido-3'-deoxythymidine.

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