RT Journal Article
SR Electronic
T1 Development of Resistance to 4’-Ethynyl-2-Fluoro-2’-Deoxyadenosine (EFdA) by WT and Nucleoside Reverse Transcriptase Inhibitor Resistant Human Immunodeficiency Virus Type 1
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.09.04.281485
DO 10.1101/2020.09.04.281485
A1 Maria E. Cilento
A1 Eleftherios Michailidis
A1 Tatiana V. Ilina
A1 Eva Nagy
A1 Hiroaki Mitsuya
A1 Michael A. Parniak
A1 Philip R. Tedbury
A1 Stefan G. Sarafianos
YR 2020
UL http://biorxiv.org/content/early/2020/09/04/2020.09.04.281485.abstract
AB 4’-ethynyl-2-fluoro-2’-deoxyadenosine (EFdA, MK-8591, islatravir) is a nucleoside reverse transcriptase translocation inhibitor (NRTTI) with exceptional potency against WT and drug-resistant HIV strains. However, HIV resistance to EFdA is not well characterized. We therefore developed resistance to EFdA by serial passages using progressively increasing concentrations of EFdA. The starting virus was either WT or clinically relevant NRTI-resistant viruses K65R, M184V, and D67N/K70R/T215F/K219Q). In all cases, the selected mutations included M184V. Additional mutations in the RT connection domain (R358K and E399K) and one mutation in the RNase H domain (A502V) were noted. Site-specific mutagenesis validated the role for M184V as the primary determinant for resistance to EFdA; none of the connection domain mutations contributed significantly to phenotypic resistance to EFdA. A novel EFdA resistance mutation was also observed in the background of M184V. The A114S/M184V combination of mutations imparted higher resistance to EFdA (~24-fold) than M184V (−8-fold) or A114S (~2-fold) alone. Virus fitness data suggested that A114S affects HIV fitness by itself and in the presence of M184V. This is consistent with biochemical experiments that showed decreases in the enzymatic efficiency (kcat/Km) of WT RT vs. A114S (2.1-fold) and A114S/M184V/502V (6.5-fold), whereas there was no significant effect of A502V on RT or virus fitness. The observed EFdA resistance of M184V by itself and in combination with A114S combined with the strong published in vitro and in vivo data, confirm that EFdA is an excellent candidate as a potential HIV therapeutic.Competing Interest StatementThe authors declare that H.M. is a coinventor of EFdA.