Inhibition of human cytomegalovirus DNA maturation by a benzimidazole ribonucleoside is mediated through the UL89 gene product.
2-Bromo-5,6-dichloro-1-beta-D-ribofuranosyl benzimidazole (BDCRB) is a member of a new class of benzimidazole ribonucleosides which inhibit human cytomegalovirus (HCMV) late in the replication cycle without inhibiting viral DNA synthesis. We show here that polygenomic concatemeric HCMV DNA does not mature to unit genome length in the presence of BDCRB. To discover the locus of action, virus resistant to BDCRB was selected by serial passage in the presence of the compound. Genetic mapping experiments with BDCRB-resistant virus demonstrated that the resistance phenotype mapped to one amino acid (Asp344Glu; low resistance) or two amino acids (Asp344Glu and Ala355Thr; high resistance) within the product of exon 2 of the HCMV U(L)89 open reading frame. The HCMV U(L)89 open reading frame and its homologs are among the most conserved open reading frames in the herpesviruses, and their products have sequence similarities to a known ATP-dependent endonuclease from the double-stranded DNA bacteriophage T4. These findings strongly suggest that BDCRB prevents viral DNA maturation by interacting with a U(L)89 gene product and that the U(L)89 open reading frame may encode an endonucleolytic subunit of the putative HCMV terminase. Further, since mammalian cell DNA replication does not involve a DNA maturation step, compounds which inhibit viral DNA maturation should be selective and safe.
Underwood
M R
MR
Department of Virology, Glaxo Wellcome Inc., Research Triangle Park, North Carolina 27709, USA. mru43326@glaxowellcome.com
Harvey
R J
RJ
Stanat
S C
SC
Hemphill
M L
ML
Miller
T
T
Drach
J C
JC
Townsend
L B
LB
Biron
K K
KK
D000595:Amino Acid Sequence; D000998:Antiviral Agents / Q000494:pharmacology*; D001483:Base Sequence; D001562:Benzimidazoles / Q000494:pharmacology*; D002460:Cell Line; D002874:Chromosome Mapping; D003587:Cytomegalovirus / Q000187:drug effects* / Q000235:genetics* / Q000502:physiology; D017931:DNA Primers / Q000235:genetics; D004261:DNA Replication / Q000187:drug effects; D004279:DNA, Viral / Q000096:biosynthesis*; D004352:Drug Resistance, Microbial / Q000235:genetics; D005814:Genes, Viral; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010641:Phenotype; D014176:Protein Biosynthesis / Q000187:drug effects; D012263:Ribonucleosides / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism*; D014779:Virus Replication / Q000187:drug effects
C109864:2-bromo-5,6-dichloro-1-beta-D-ribofuranosyl benzimidazole; D000998:Antiviral Agents; D001562:Benzimidazoles; D017931:DNA Primers; D004279:DNA, Viral; D012263:Ribonucleosides; D014764:Viral Proteins