Nonnucleoside Reverse Transcriptase Inhibitor Hypersusceptibility and Resistance by Mutation of Residue 181 in HIV-1 Reverse Transcriptase

Abstract

Substitutions at residue Y181 in HIV-1 reverse transcriptase (RT), in particular, Y181C, Y181I, and Y181V, are associated with nonnucleoside RT inhibitor (NNRTI) cross-resistance. In this study, we used kinetic and thermodynamic approaches, in addition to molecular modeling, to gain insight into the mechanisms by which these substitutions confer resistance to nevirapine (NVP), efavirenz (EFV), and rilpivirine (RPV). Using pre-steady-state kinetics, we found that the dissociation constant (K d ) values for inhibitor binding to the Y181C and Y181I RT-template/primer (T/P) complexes were significantly reduced. In the presence of saturating concentrations of inhibitor, the Y181C RT-T/P complex incorporated the next correct deoxynucleoside triphosphate (dNTP) more efficiently than the wild-type (WT) complex, and this phenotype correlated with decreased mobility of the RT on the T/P substrate. Interestingly, we found that the Y181F substitution in RT-which represents a transitional mutation between Y181 and Y181I/V, or a partial revertant-conferred hypersusceptibility to EFV and RPV at both the virus and enzyme levels. EFV and RPV bound more tightly to Y181F RT-T/P. Furthermore, inhibitor-bound Y181F RT-T/P was less efficient than the WT complex in incorporating the next correct dNTP, and this could be attributed to increased mobility of Y181F RT on the T/P substrate. Collectively, our data highlight the key role that Y181 in RT plays in NNRTI binding.

HIV MDR is still a relevant issue despite its dramatic drop over the years

“…Concerning specific drug-classes, we found that resistance to PIs, NRTIs and NNRTIs dramatically decreased over time. However, resistance to NNRTIs has been stable at around 25% from 2011 to 2018 and NNRTI-MRMs such as Y181C, associated with wide crossresistance to NNRTIs 18,19 , remained stable at around 4%. Moreover, we found that some rilpivirine and etravirine associated mutations at position 138 of RT increased their prevalence over time, as recently observed 13 .…”

Prevalence of drug resistant HIV‐1 forms in patients without any history of antiretroviral therapy in the Republic of Guinea

“…Among the mutations associated with HIV resistance to nonnucleoside reverse transcriptase inhibitors, a relatively rare, nonpolymorphic V179T mutation has been shown, which is sometimes selected for in patients receiving NNRTIs. This is due to a minimal decrease in the sensitivity to etravirine and rilpivirine 29,31 . Several substitutions were also encountered at position 238: K238T, which reduces susceptibility to nevirapine and efavirenz by about 5‐fold; K238R, which is a common polymorphism that does not reduce susceptibility to NNRTIs 32 ; and K238E, a rare mutation at this position, the effect of which is not well described in the literature.…”

“…This is due to a minimal decrease in the sensitivity to etravirine and rilpivirine. 29,31 Several substitutions were also encountered at position 238: K238T, which reduces susceptibility to nevirapine and efavirenz by about 5-fold; K238R, which is a common polymorphism that does not reduce susceptibility to NNRTIs 32 ; and K238E, a rare mutation at this position, the effect of which is not well described in the literature.…”

Discovery of Benzisothiazolone Derivatives as Bifunctional Inhibitors of HIV-1 Reverse Transcriptase DNA Polymerase and Ribonuclease H Activities

“…Next, we re-purchased hit compounds with IC50 values < 1.0 µM for inhibition of RT RNase H activity that were available in sufficient quantities for further analysis. We assessed their antiviral activity and cytotoxicty in TZM-bl cells, as described previously [13]. Of these compounds, only two 2) (Figure 3)), which both shared the same benzisothiazolone pharmacophore (Figure 3, red), demonstrated robust antiviral activity in the absence of cellular toxicity (Table 1).…”