title: [Resistance of human immunodeficiency virus (HIV) to zidovudine. Genotypic analysis in strains isolated from Chilean patients].
abstract: BACKGROUND
  Resistance of HIV to AZT is the result of mutations in the pol gene that codifies the enzyme reverse transcriptase.
  
  
  OBJECTIVE
  To assess the resistance to antiretroviral drugs in Chilean patients infected with HIV.
  
  
  METHODS
  The presence of mutations was searched in 22 patients infected with HIV. The emergence or persistence of these mutations was studied in sequential samples of 19 patients. The presence of the mutation that confers resistance to didanosine (DDI) was studied in those subjects exposed to the drug. Polymerase chain reaction techniques were used to analyze mutations in codons 41, 70 and 215 of the pol gene (resistance to AZT) and the mutation in codon 71 (resistance to DDI).
  
  
  RESULTS
  On admission, none of the patients without previous exposure to AZT had drug resistance mutations. Seven of 12 patients (58.3%) that had received AZT had mutations in codon 215. In two, they were associated to a mutation in codon 41 and in two, a mutation in codon 70. After a mean follow up of 14 months, 13 of 15 patients (86%) that received AZT had viral strains genotypically resistant to the drug. In nine of these, the resistance was associated with disease progression. None of the 10 patients that received DDI had the mutation in codon 74 that confers resistance to the drug. However, in one of these patients, that never received AZT, a virus with a mutation in codon 215 was detected.
  
  
  CONCLUSIONS
  A high percentage of patients that have received monotherapy with AZT have genotypic resistance to the drug. This resistance is associated with clinical and immunological derangement in 70% of these subjects.
authors.affiliation: Centro de Investigaciones Médicas, Facultad de Medicina, P Universidad Católica de Chile, Santiago de Chile.
authors.forename: P A
authors.initials: PA
authors.lastname: Vial
authors.forename: C
authors.initials: C
authors.lastname: Vial
authors.forename: K
authors.initials: K
authors.lastname: Abarca
authors.forename: M
authors.initials: M
authors.lastname: Noriega
authors.forename: G
authors.initials: G
authors.lastname: Jiménez
authors.forename: J
authors.initials: J
authors.lastname: Labarca
authors.forename: J
authors.initials: J
authors.lastname: Gasep
authors.forename: O
authors.initials: O
authors.lastname: Palacios
authors.forename: C
authors.initials: C
authors.lastname: Pérez
authors.forename: G
authors.initials: G
authors.lastname: Acuña
mesh_terms: D019380:Anti-HIV Agents / Q000627:therapeutic use*; D002677:Chile; D003062:Codon / Q000187:drug effects / Q000235:genetics; D004351:Drug Resistance; D005500:Follow-Up Studies; D005838:Genotype; D006678:HIV / Q000187:drug effects* / Q000235:genetics*; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D011446:Prospective Studies; D015215:Zidovudine / Q000627:therapeutic use*
chemical_list: D019380:Anti-HIV Agents; D003062:Codon; D015215:Zidovudine
vernacular_title: Resistencia del virus de inmunodeficiencia humano (VIH) a zidovudina (AZT): análisis genotípico en cepas aisladas de pacientes chilenos.