Potent and selective inhibition of human cytomegalovirus replication by 1263W94, a benzimidazole L-riboside with a unique mode of action.
Benzimidazole nucleosides have been shown to be potent inhibitors of human cytomegalovirus (HCMV) replication in vitro. As part of the exploration of structure-activity relationships within this series, we synthesized the 2-isopropylamino derivative (3322W93) of 1H-beta-D-ribofuranoside-2-bromo-5,6-dichlorobenzimidazole (BDCRB) and the biologically unnatural L-sugars corresponding to both compounds. One of the L derivatives, 1H-beta-L-ribofuranoside-2-isopropylamino-5,6-dichlorobenzimidazole (1263W94), showed significant antiviral potency in vitro against both laboratory HCMV strains and clinical HCMV isolates, including those resistant to ganciclovir (GCV), foscarnet, and BDCRB. 1263W94 inhibited viral replication in a dose-dependent manner, with a mean 50% inhibitory concentration (IC(50)) of 0.12 +/- 0.01 microM compared to a mean IC(50) for GCV of 0.53 +/- 0.04 microM, as measured by a multicycle DNA hybridization assay. In a single replication cycle, 1263W94 treatment reduced viral DNA synthesis, as well as overall virus yield. HCMV mutants resistant to 1263W94 were isolated, establishing that the target of 1263W94 was a viral gene product. The resistance mutation was mapped to the UL97 open reading frame. The pUL97 protein kinase was strongly inhibited by 1263W94, with 50% inhibition occurring at 3 nM. Although HCMV DNA synthesis was inhibited by 1263W94, the inhibition was not mediated by the inhibition of viral DNA polymerase. The parent benzimidazole D-riboside BDCRB inhibits viral DNA maturation and processing, whereas 1263W94 does not. The mechanism of the antiviral effect of L-riboside 1263W94 is thus distinct from those of GCV and of BDCRB. In summary, 1263W94 inhibits viral replication by a novel mechanism that is not yet completely understood.
Department of Clinical Virology, GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, NC 27709, USA. kkb21173@gsk.com
Karen K
KK
Biron
Robert J
RJ
Harvey
Stanley C
SC
Chamberlain
Steven S
SS
Good
Albert A
AA
Smith
Michelle G
MG
Davis
Christine L
CL
Talarico
Wayne H
WH
Miller
Robert
R
Ferris
Ronna E
RE
Dornsife
Sylvia C
SC
Stanat
John C
JC
Drach
Leroy B
LB
Townsend
George W
GW
Koszalka
D000998:Antiviral Agents / Q000494:pharmacology* / Q000633:toxicity; D001562:Benzimidazoles / Q000494:pharmacology*; D015415:Biomarkers; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D004279:DNA, Viral / Q000187:drug effects; D004259:DNA-Directed DNA Polymerase / Q000096:biosynthesis / Q000235:genetics; D004351:Drug Resistance; D004352:Drug Resistance, Microbial; D015672:Erythroid Precursor Cells / Q000187:drug effects; D005347:Fibroblasts; D006801:Humans; D019384:Nucleic Acid Synthesis Inhibitors; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D012263:Ribonucleosides / Q000494:pharmacology*; D017422:Sequence Analysis, DNA; D013329:Structure-Activity Relationship; D014779:Virus Replication / Q000187:drug effects*; D004004:Dichlororibofuranosylbenzimidazole / Q000031:analogs & derivatives
D000998:Antiviral Agents; D001562:Benzimidazoles; D015415:Biomarkers; D004279:DNA, Viral; D004259:DNA-Directed DNA Polymerase; D019384:Nucleic Acid Synthesis Inhibitors; D011494:Protein Kinases; D012263:Ribonucleosides; C400401:maribavir; D004004:Dichlororibofuranosylbenzimidazole