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.