title: Heterogeneity and evolution of thymidine kinase and DNA polymerase mutants of herpes simplex virus type 1: implications for antiviral therapy.
abstract: BACKGROUND
  Infections caused by acyclovir-resistant isolates of herpes simplex virus (HSV) after hematopoietic stem cell transplantation (HSCT) are an emerging concern. An understanding of the evolutionary aspects of HSV infection is crucial to the design of effective therapeutic and control strategies.
  
  
  METHODS
  Eight sequential HSV-1 isolates were recovered from an HSCT patient who suffered from recurrent herpetic gingivostomatitis and was treated alternatively with acyclovir, ganciclovir, and foscavir. The diverse spectra and temporal changes of HSV drug resistance were determined phenotypically (drug-resistance profiling) and genotypically (sequencing of the viral thymidine kinase and DNA polymerase genes).
  
  
  RESULTS
  Analysis of 60 clones recovered from the different isolates demonstrated that most of these isolates were heterogeneous mixtures of variants, indicating the simultaneous infection with different drug-resistant viruses. The phenotype/genotype of several clones associated with resistance to acyclovir and/or foscavir were identified. Two novel mutations (E798K and I922T) in the viral DNA polymerase could be linked to drug resistance.
  
  
  CONCLUSIONS
  The heterogeneity within the viral populations and the temporal changes of drug-resistant viruses found in this HSCT recipient were remarkable, showing a rapid evolution of HSV-1. Drug-resistance surveillance is highly recommended among immunocompromised patients to manage the clinical syndrome and to avoid the emergence of multidrug-resistant isolates.
authors: Laboratory of Virology, Rega Institute for Medical Research, K U Leuven, Minderbroedersstraat 10, Leuven, Belgium.
authors: Graciela
authors: G
authors: Andrei
authors: Aspasia
authors: A
authors: Georgala
authors: Dimitri
authors: D
authors: Topalis
authors: Pierre
authors: P
authors: Fiten
authors: Michel
authors: M
authors: Aoun
authors: Ghislain
authors: G
authors: Opdenakker
authors: Robert
authors: R
authors: Snoeck
mesh_terms: D000212:Acyclovir / Q000494:pharmacology; D000328:Adult; D004279:DNA, Viral / Q000032:analysis / Q000235:genetics; D024921:Drug Resistance, Multiple, Viral; D019143:Evolution, Molecular; D005260:Female; D015774:Ganciclovir / Q000494:pharmacology; D015751:Genes, pol; D018740:Genetic Heterogeneity; D005838:Genotype; D018380:Hematopoietic Stem Cell Transplantation; D018259:Herpesvirus 1, Human / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000473:pathology; D009154:Mutation; D010641:Phenotype; D013283:Stomatitis, Herpetic / Q000188:drug therapy* / Q000473:pathology / Q000821:virology; D013937:Thymidine Kinase / Q000235:genetics*
chemical_list: D004279:DNA, Viral; D013937:Thymidine Kinase; D015774:Ganciclovir; D000212:Acyclovir