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Updated: Jun 16, 2026

Rapid Screening of HIV Reverse Transcriptase and Integrase Inhibitors
Published on: April 9, 2014
N348I in reverse transcriptase provides a genetic pathway for HIV-1 to select thymidine analogue mutations and
Jessica Radzio1, Soo-Huey Yap, Gilda Tachedjian
1Department of Medicine, University of Pittsburgh School of Medicine, PA, USA.
Objective:
Several nonnucleoside (e.g. Y181C) and nucleoside (e.g. L74V and M184V) resistance mutations in HIV-1 reverse transcriptase are antagonistic toward thymidine analogue mutations (TAMs) that confer zidovudine (ZDV) resistance. The N348I mutation in the connection domain of reverse transcriptase also confers ZDV resistance; however, the mechanisms involved are different from TAMs. In this study, we examined whether N348I compensates for the antagonism of the TAM K70R by Y181C, L74V and M184V.
Design And Methods:
The ZDV monophosphate and ribonuclease H activities of recombinant-purified HIV-1 reverse transcriptase-containing combinations of K70R, N348I and Y181C, L74V or M184V were assessed using standard biochemical and antiviral assays.
Results:
As expected, the introduction of the Y181C, L74V or M184V mutations into K70R HIV-1 reverse transcriptase significantly diminished the ATP-mediated ZDV monophosphate excision activity of the enzyme. However, the N348I mutation compensated for this antagonism on RNA/DNA template/primers by significantly decreasing the frequency of secondary ribonuclease H cleavages that reduce the overall efficiency of the excision reaction.
Conclusion:
The acquisition of N348I in HIV-1 reverse transcriptase - which can occur early in therapy, oftentimes before TAMs - may provide a simple genetic pathway that allows the virus to select both TAMs and mutations that are antagonistic toward TAMs.
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