title: Dendritic keratitis caused by an acyclovir-resistant herpes simplex virus with frameshift mutation.
abstract: OBJECTIVE
  To report a case of acyclovir-resistant herpes simplex virus (HSV) keratitis after long-term, inconsistent use of topical acyclovir and fluorometholone.
  
  
  METHODS
  A 70-year-old man with dendritic keratitis caused by an acyclovir-resistant HSV strain was examined. The 50% inhibitory concentration of different antiviral agents against the isolated virus and the DNA sequence of viral thymidine kinase were determined.
  
  
  RESULTS
  The 50% inhibitory concentration of acyclovir and trifluorothymidine for the isolated HSV strain was 13.75 and 0.28 microg/mL, respectively, indicating that the virus was resistant to acyclovir. DNA sequencing of the viral thymidine kinase revealed that this virus had a frameshift mutant with a G insertion in the 7Gs homopolymer. Topical trifluorothymidine was effective, and the epithelial lesion was completely resolved within 2 weeks.
  
  
  CONCLUSIONS
  A typical form of dendritic keratitis was caused by an acyclovir-resistant HSV with frameshift mutation in a 7Gs homopolymer region.
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Shitsukawa, Toon-City, Ehime, Japan. zhangwei@m.ehime-u.ac.jp
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shiraishi
authors.forename: Ichiroh
authors.initials: I
authors.lastname: Shimamura
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Inoue
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ohashi
mesh_terms: D000212:Acyclovir / Q000627:therapeutic use*; D000368:Aged; D000998:Antiviral Agents / Q000627:therapeutic use*; D004279:DNA, Viral / Q000032:analysis; D024882:Drug Resistance, Viral; D016368:Frameshift Mutation; D006801:Humans; D007635:Keratitis, Dendritic / Q000188:drug therapy / Q000821:virology*; D008297:Male; D018139:Simplexvirus / Q000187:drug effects* / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D013937:Thymidine Kinase; D000212:Acyclovir