Characterization of amino acids Arg, Ser and Thr at position 70 within HIV-1 reverse transcriptase

Abstract

Objectives:

The amino acid position 70 in HIV-1 reverse transcriptase (RT) plays an important role in nucleoside RT inhibitor (NRTI) resistance. K70R is part of the thymidine analog mutations, but also other amino acid changes have been associated with NRTI resistance, such as K70E and K70G. In this study, we investigated the in vivo selection of the HIV-1 RT mutations K70S and K70T and their in vitro effect on drug resistance and replication capacity.

Methods:

Recombinant viruses with RT mutations were generated to measure the in vitro drug susceptibility and replication capacity. Bayesian network analysis and three-dimensional modeling were performed to understand the selection and impact of the RT70 mutations.

Results:

K70S and K70T were found at a low frequency in RTI-experienced HIV-1 patients (0.10% and 0·20%). Baeyesian network learning identified no direct association with the in vivo exposure to any specific RTI. However, direct associations of K70S with mutations within the Q151M-complex and of K70T with K65R were observed. In vitro phenotypic testing revealed only minor effects of K70R/S/T as single mutations, associated with Q151M and within the context of the Q151M-complex.

Discussion:

These results suggest that the selection of K70S/T and their phenotypic impact are influenced by the presence of other mutations in RT. However, the low impact on in vitro phenotype here observed, alongside with the low in vivo prevalence, the exclusive direct association with known major RTI mutations and the unknown correlation with in vivo response, do not yet necessitate the inclusion of K70S/T in drug resistance interpretation systems.

Keywords:

• HIV-1
• Resistance
• Mutation
• Reverse transcriptase

Acknowledgements

The authors would like to thank Yoeri Schrooten and Gertjan Beheydt for outstanding technical assistance. Kris Covens was supported by a PhD grant of the Institute for the Promotion of Innovation through Sciences and Technology in Flanders (IWT). This work was supported by the Fonds voor Wetenschappelijk Onderzoek Vlaanderen (grant no. G.0692·14N), by the European Community’s Seventh Framework Program (FP7/2007–2013) under the project ‘Collaborative HIV and Anti-HIV Drug Resistance Network (CHAIN)’ (no. 223131), by KU Leuven (Program Financing no. PF/10/018), by the AIDS Reference Laboratory of Leuven that receives support from the Belgian Ministry of Social Affairs through a fund within the Health Insurance System, and by the Canadian Institutes of Health Research through funding to Matthias Götte. Molecular graphics images were produced using the UCSF Chimera package from the Resource for Biocomputing, Visualization, and Informatics at the University of California, San Francisco (supported by NIH P41 RR001081).

This work has been partly presented at the 17th Conference on Retroviruses and Opportunistic Infections, San Francisco, CA, USA, February 16–19, 2010.