title: Zidovudine resensitization and dual HIV-1 resistance to zidovudine and lamivudine in the delta lamivudine roll-over study.
abstract: OBJECTIVE
  To study zidovudine resensitization and dual resistance to zidovudine/lamivudine in HIV-1 isolates from nucleoside reverse transcriptase (RT) inhibitor-experienced patients during selective pressure exerted by zidovudine/lamivudine combination therapy.
  
  
  METHODS
  HIV-1 isolates from 29 patients receiving zidovudine/lamivudine combination therapy in the Delta roll-over study were analysed at entry and during a 1 year follow-up period for phenotypic susceptibility to zidovudine and lamivudine in the ANRS PBMC assay. The RT gene from codon 20 to 230 and at codon 333 was analysed by nucleotide sequencing of the corresponding isolates.
  
  
  RESULTS
  HIV-1 isolates from 23 of the 29 patients were phenotypically resistant to zidovudine at baseline; 61% of these patients showed significant zidovudine resensitization during follow-up. The zidovudine IC50 value correlated positively with log10 plasma HIV-1 RNA (P = 0.02) and negatively with the CD4 cell count (P = 0.004). Zidovudine resensitization (related to acquisition of the M184V mutation) was transient, with evolution towards dual resistance to zidovudine and lamivudine in 20 of the 29 patients. The phenotype of certain dually resistant isolates coincided with the emergence of multiple mutations in the 5' part of the RT gene.
  
  
  CONCLUSIONS
  M184V-mediated zidovudine resensitization of HIV-1 is transient in most patients who are given zidovudine/lamivudine combination therapy when zidovudine resistance has already emerged. The subsequent evolution towards dual phenotypic resistance to zidovudine/lamivudine corresponds to complex genotypic profiles.
authors.affiliation: Laboratoire de Virologie, University Hospital of Bordeaux, France. bernard.masquelier@viro.u-bordeaux2.fr
authors.forename: B
authors.initials: B
authors.lastname: Masquelier
authors.forename: D
authors.initials: D
authors.lastname: Descamps
authors.forename: I
authors.initials: I
authors.lastname: Carrière
authors.forename: F
authors.initials: F
authors.lastname: Ferchal
authors.forename: G
authors.initials: G
authors.lastname: Collin
authors.forename: M
authors.initials: M
authors.lastname: Denayrolles
authors.forename: A
authors.initials: A
authors.lastname: Ruffault
authors.forename: B
authors.initials: B
authors.lastname: Chanzy
authors.forename: J
authors.initials: J
authors.lastname: Izopet
authors.forename: C
authors.initials: C
authors.lastname: Buffet-Janvresse
authors.forename: M P
authors.initials: MP
authors.lastname: Schmitt
authors.forename: E
authors.initials: E
authors.lastname: Race
authors.forename: H J
authors.initials: HJ
authors.lastname: Fleury
authors.forename: J P
authors.initials: JP
authors.lastname: Aboulker
authors.forename: P
authors.initials: P
authors.lastname: Yeni
authors.forename: F
authors.initials: F
authors.lastname: Brun-Vézinet
mesh_terms: D019380:Anti-HIV Agents / Q000494:pharmacology*; D018791:CD4 Lymphocyte Count; D004311:Double-Blind Method; D004351:Drug Resistance; D005838:Genotype; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology*; D010641:Phenotype; D012367:RNA, Viral / Q000097:blood; D015215:Zidovudine / Q000494:pharmacology*
chemical_list: D019380:Anti-HIV Agents; D012367:RNA, Viral; D019259:Lamivudine; D015215:Zidovudine; D054303:HIV Reverse Transcriptase