title: [Presence of mutations associated with ganciclovir resistance in cytomegalovirus UL97 gene].
abstract: BACKGROUND
  Long term use of ganciclovir (GCV) is associated with acquired resistance to it. Ninety percent of the responsible mutations occur in cytomegalovirus (CMV) UL 97 gene.
  
  
  OBJECTIVE
  To search for these mutations, comparing nucleotide sequences of CMV-positive samples from post transplant and immunocompromised patients receiving GCV, with sequences of CMV isolates obtained from subjects not exposed to the drug.
  
  
  METHODS
  Codons 440 to 465 of gene UL 97, including the most common mutations causing resistance to GCV, were amplified in 33 plasma samples from patients exposed to GCV and in 15 urine samples of newborns. Both populations and their nucleotide sequences were compared with the prototype strain CMV AD169.
  
  
  RESULTS
  Samples of exposed patients had multiple mutations but only one had a mutation associated with clinical resistance (M460I). Eight subjects had the D605E mutation, whose role in resistance is controversial. The remaining 150 mutations were silent mutations.
  
  
  CONCLUSIONS
  A low frequency of mutations associated with CMV resistance to GCV was found in these exposed and unexposed samples. These mutations may reflect coexistence of multiple genetic variants of CMV. The absence of clinical expression of resistance, even with these mutations, can be explained by the use of GCV for a shorter lapse than that associated with the appearance of resistance.
authors.affiliation: Departamento de Pediatría, Centro de Investigaciones Médicas, Pontificia Universidad Católica de Chile, Chile.
authors.forename: María Angélica
authors.initials: MA
authors.lastname: Oyarzún
authors.forename: Patricia
authors.initials: P
authors.lastname: Bustos
authors.forename: Marcela
authors.initials: M
authors.lastname: González
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Domínguez
authors.forename: Francisco
authors.initials: F
authors.lastname: Aguayo
authors.forename: Bruno
authors.initials: B
authors.lastname: Nervi
authors.forename: Marcela
authors.initials: M
authors.lastname: Ferres
mesh_terms: D000293:Adolescent; D000328:Adult; D000998:Antiviral Agents / Q000494:pharmacology*; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D002677:Chile; D003587:Cytomegalovirus / Q000187:drug effects / Q000235:genetics*; D024882:Drug Resistance, Viral / Q000235:genetics*; D015774:Ganciclovir / Q000494:pharmacology*; D016679:Genome, Viral; D006801:Humans; D016867:Immunocompromised Host; D008875:Middle Aged; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D055815:Young Adult
chemical_list: D000998:Antiviral Agents; D017853:Phosphotransferases (Alcohol Group Acceptor); C075365:ganciclovir kinase; D015774:Ganciclovir