In vitro suppression of k65r reverse transcriptase-mediated tenofovir- and adefovir-5′-diphosphate resistance conferred by the boranophosphonate derivatives

Abstract

9-[2-(Boranophosphonomethoxy)ethyl]adenine diphosphate (BH 3-PMEApp) and (R)-9-[2-(boranophosphonomethoxy)propyl]adenine diphosphate (BH3-PMPApp), described here, represent the first nucleoside phosphonates modified on their α-phosphates that act as efficient substrates for the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). These analogues were synthesized and evaluated for their in vitro activity against wild-type (WT), K65R, and R72A RTs. BH 3-PMEApp and BH3-PMPApp exhibit the same inhibition properties as their nonborane analogues on WT RT. However, K65R RT was found hypersensitive to BH3-PMEApp and as sensitive as WT RT to BH 3-PMPApp. Moreover, the presence of the borane group restores incorporation of the analogue by R72A HIV RT, the latter being nearly inactive with regular nucleotides. The BH3-mediated suppression of HIV-1 RT resistance, formerly described with nucleoside 5′-(α-p-borano)- triphosphate analogues, is thus also conserved at the phosphonate level. The present results show that an α-phosphate modification is also possible and interesting for phosphonate analogues, a result that might find application in the search for a means to control HIV RT-mediated drug resistance. Copyright © 2007, American Society for Microbiology. All Rights Reserved.