title: The preferential selection of K65R in HIV-1 subtype C is attenuated by nucleotide polymorphisms at thymidine analogue mutation sites.
abstract: OBJECTIVE
  We recently reported the preferential selection of the K65R resistance mutation in subtype C HIV-1 compared with subtype B and showed the underlying mechanism to be dependent on subtype C-specific silent nucleotide polymorphisms, i.e. genomic mutations that change the genotype but not the phenotype. The number of clinical reports demonstrating elevated numbers of K65R nevertheless suggests the existence of factors limiting the increased incidence of K65R mutations. Thus, we investigated the contributions of subtype C-specific silent nucleotide polymorphisms at thymidine analogue mutation (TAM) sites 70, 210 and/or 219 that might reduce the previously described preferential selection of K65R in subtype C HIV-1 associated with subtype C-specific nucleotide polymorphisms at sites 64/65.
  
  
  METHODS
  Cell culture drug selections were performed with various drugs in MT2 cells.
  
  
  RESULTS
  The use of nucleoside/nucleotide reverse transcriptase inhibitors [N(t)RTIs] as single drugs or in combination confirmed the more frequent selection of K65R by multiple N(t)RTIs in a subtype B virus that contained the 64/65 nucleotide polymorphisms of subtype C than in a wild-type subtype B virus. This effect was attenuated in the presence of several silent TAM nucleotide polymorphisms, except when stavudine was employed in the selection protocol.
  
  
  CONCLUSIONS
  These results further demonstrate that stavudine can preferentially select for K65R in subtype C virus and also provide a basis for understanding the importance of silent nucleotide polymorphisms in regard to altered HIV drug resistance profiles.
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Montréal, Québec, Canada.
authors.forename: Cédric F
authors.initials: CF
authors.lastname: Invernizzi
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Coutsinos
authors.forename: Maureen
authors.initials: M
authors.lastname: Oliveira
authors.forename: Rita S
authors.initials: RS
authors.lastname: Schildknecht
authors.forename: Hongtao
authors.initials: H
authors.lastname: Xu
authors.forename: Simani
authors.initials: S
authors.lastname: Gaseitsiwe
authors.forename: Daniela
authors.initials: D
authors.lastname: Moisi
authors.forename: Bluma G
authors.initials: BG
authors.lastname: Brenner
authors.forename: Mark A
authors.initials: MA
authors.lastname: Wainberg
mesh_terms: D019380:Anti-HIV Agents / Q000494:pharmacology*; D002460:Cell Line; D024882:Drug Resistance, Viral; D005838:Genotype; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D020125:Mutation, Missense; D011110:Polymorphism, Genetic; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology; D012641:Selection, Genetic; D013936:Thymidine / Q000235:genetics*
chemical_list: D019380:Anti-HIV Agents; D018894:Reverse Transcriptase Inhibitors; D013936:Thymidine
keywords: K65R resistance mutation; N(t)RTIs; TAMs; cell culture drug selections; nucleotide polymorphisms; subtype differences B/C