Effect of tenofovir subtraction on HIV plasma viraemia, CD4+ T-cell count and resistance in a patient with baseline K65R and M184V mutations.

In vitro, the reverse transcriptase mutation K65R can simultaneously reduce drug susceptibility, replicative capacity and restrict HIV-1 replication. Here, we assessed the effect of tenofovir discontinuation for a patient receiving antiretroviral therapy whose HIV-1 had a dominant K65R/M184V genotype. Although limited by the single-case nature, the data support a hypothesis that there is no HIV viral RNA or CD4+ T-cell count benefit of taking tenofovir for experienced patients with genotypic evidence of K65R/M184V.

Differential impact of thymidine analogue mutations on emtricitabine and lamivudine susceptibility.

The impact of drug resistance-associated mutations on subsequent antiretroviral therapy is an important consideration in managing treatment-experienced, HIV-1-infected patients. Lamivudine (3TC) and emtricitabine (FTC) are structurally related nucleoside reverse transcriptase inhibitors (NRTIs) approved for use in HIV-1-infected individuals. To evaluate whether susceptibility differences exist between lamivudine and emtricitabine, the phenotypic impact of common NRTI resistance-associated mutations was compared in HIV-1 from patient samples with paired FTC and 3TC susceptibility results.

Phenotypic impact of HIV reverse transcriptase M184I/V mutations in combination with single thymidine analog mutations on nucleoside reverse transcriptase inhibitor resistance.

Objectives: To analyse the impact of the M184I/V mutation and individual thymidine-associated mutations (TAM) on nucleoside reverse transcriptase inhibitor (NRTI) phenotypic susceptibility and compare these results with those obtained using commercial and public algorithms.

Design: An HIV genotypic/phenotypic database with over 27 000 samples was used to obtain the median fold change (5-95th percentile) in NRTI phenotypic susceptibility for viruses from patients containing individual TAM with or without the M184I or V mutation and for wild-type patient viruses.

Results: The resulting data indicated that in vitro, individual TAM do not have an equivalent impact on NRTI resistance, with some individual TAM having little or no impact on NRTI resistance (e.

Nucleoside and nucleotide analogue reverse transcriptase inhibitors: a clinical review of antiretroviral resistance.

Although advances in highly active antiretroviral therapy (HAART) have made long-term suppression of HIV an achievable goal of therapy, a substantial proportion of first-line regimens will eventually fail. Successful longterm treatment requires consideration of downstream treatment options at the time of initiating or changing regimens. An understanding of the patterns and interactions of resistance mutations, and the appropriate use of genotypic and phenotypic testing is an important component of successful drug sequencing.