title: Emergence of resistance to carbocyclic oxetanocin G in herpes simplex virus type 1 and genetic analysis of resistant mutants.
abstract: OBJECTIVE
  To elucidate the potentiality of emergence of drug-resistance to carbocyclic oxetanocin G (C.OXT-G), a new effective antiviral drug for herpetic keratitis during treatment and the mechanism of this drug resistance.
  
  
  METHODS
  A C.OXT-G resistant strain (C.OXT-Gr) was established by serially propagating the herpes simplex virus (HSV) -1 in African green monkey kidney (VERO) cells in the presence of C.OXT-G. After the drug sensitivity assay and the thymidine kinase (TK) activity assay, the molecular basis for the drug resistance was studied using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and PCR direct sequencing technology.
  
  
  RESULTS
  After the 10th passage in 10 microm C.OXT-G, the ED50 of the C.OXT-Gr was 17.08-fold greater than that of the original strain on the average and the TK activities of these resistant strains were extremely reduced. PCR-SSCP analysis on TK gene of the wild HSV-1 and the C.OXT-Gr showed altered migration patterns in part 3 and part 4, while PCR-SSCP analysis on DNA polymerase gene showed no difference among the viruses. Sequence analysis revealed a deletion of G at position of 430 that caused frameshift, resulting in premature termination in the TK gene.
  
  
  CONCLUSIONS
  The drug resistance to C.OXT-G may appear during the treatment due to the deficiency of TK activity caused by a single mutation in the TK gene of HSV-1.
authors.affiliation: Department of Ophthalmology, Affiliated Hospital of Nantong Medical College, Nantong 226001, China. gongyp@pub.nt.jsinfo.net
authors.forename: Nan
authors.initials: N
authors.lastname: Hu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shiota
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002522:Chlorocebus aethiops; D004279:DNA, Viral / Q000235:genetics; D024882:Drug Resistance, Viral; D017353:Gene Deletion; D006147:Guanine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D018259:Herpesvirus 1, Human / Q000201:enzymology / Q000235:genetics*; D009154:Mutation; D019384:Nucleic Acid Synthesis Inhibitors; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D013937:Thymidine Kinase / Q000235:genetics* / Q000378:metabolism; D014709:Vero Cells
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D019384:Nucleic Acid Synthesis Inhibitors; D006147:Guanine; C063638:lobucavir; D013937:Thymidine Kinase