Resistance of human immunodeficiency virus type 1 to acyclic 6-phenylselenenyl- and 6-phenylthiopyrimidines.
Acyclic 6-phenylselenenyl- and 6-phenylthiopyrimidine derivatives are potent and specific inhibitors of human immunodeficiency virus type 1 (HIV-1). The development of in vitro resistance to two derivatives, 5-ethyl-1-(ethoxymethyl)-(6-phenylthio)-uracil (E-EPU), was evaluated by serial passage of HIV-1 in increasing concentrations of inhibitor. HIV-1 variants exhibiting > 500-fold resistance to E-EPSeU and E-EPU were isolated after sequential passage in 1, 5, and 10 microM inhibitor. The resistant variants exhibited coresistance to related acyclic 6-substituted pyrimidines and the HIV-1-specific inhibitors (+)-(5S)-4,5,6,7-tetrahydro-5- pyrimidines and the HIV-1-specific inhibitors (+)-(5S)-4,5,6,7-tetrahydro-5- methyl-6-(3-methyl-2-butenyl)imidazo[4,5,1-jk]benzodiazepin-2(1H)- thione (TIBO R82150) and nevirapine, but remained susceptible to 3'-azido-3'-deoxythymidine, 2',3'-dideoxycytidine, 2',3'-dideoxyinosine, and phosphonoformic acid. DNA sequence analysis of reverse transcriptase (RT) derived from E-EPSeU-resistant virus identified a Tyr (TAT)-to-Cys (TGT) mutation at either codon 188 (Cys-188; 9 of 15 clones) or codon 181 (Cys-181; 5 of 15 clones). The same amino acid changes were found in RT from E-EPU-resistant virus, but the Cys-181 mutation was more common (9 of 10 clones) than the Cys-188 mutation (1 of 10 clones). Site-specific mutagenesis and production of mutant recombinant viruses demonstrated that both the Cys-181 and Cys-188 mutations cause resistance to E-EPSeU and E-EPU. Of the two mutations, the Cys-188 substitution produced greater E-EPSeU and E-EPU resistance. The predominance of the Cys-188 mutation in E-EPSeU-resistant variants has not been noted for other classes of HIV-1 specific RT inhibitors. HIV-1 resistance is likely to limit the therapeutic efficacy of acyclic 6-substituted pyrimidines if they are used as monotherapy.
Department of Medicine, University of Pittsburgh School of Medicine, Pennsylvania.
M H
MH
Nguyen
R F
RF
Schinazi
C
C
Shi
N M
NM
Goudgaon
P M
PM
McKenna
J W
JW
Mellors
D000998:Antiviral Agents / Q000494:pharmacology*; D004351:Drug Resistance / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D009154:Mutation; D016566:Organoselenium Compounds / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014498:Uracil / Q000031:analogs & derivatives* / Q000494:pharmacology; D015215:Zidovudine / Q000494:pharmacology
D000998:Antiviral Agents; D016566:Organoselenium Compounds; C071166:5-ethyl-1-ethoxymethyl-6-(phenylthio)uracil; C091742:5-ethyl-1-(ethoxymethyl)-6-(phenylselenenyl)uracil; D015215:Zidovudine; D014498:Uracil