title: Quasispecies variant dynamics during emergence of resistance to raltegravir in HIV-1-infected patients.
abstract: OBJECTIVE
  Raltegravir is the first approved inhibitor of HIV-1 integrase (IN). In most patients, raltegravir failure is associated with mutations in the IN gene, through two different genetic pathways: 155 (N155H) or 148 (Q148K/R/H). The objective of this study was to characterize the dynamics of HIV-1 quasispecies variant populations in patients who failed to respond to raltegravir treatment.
  
  
  METHODS
  Bulk genotyping and clonal analysis were performed during the follow-up of 10 patients who failed to respond to raltegravir treatment.
  
  
  RESULTS
  Treatment failed through the 155 pathway in six patients and through the 148 pathway in two patients; two further patients switched from the 155 to the 148 pathway. In the two patients switching from the 155 to the 148 pathway, clonal analysis showed that Q148R/H and N155H mutations were present on different strands, suggesting that these two pathways are independent. This was consistent with our finding that each genetic profile was associated with different secondary mutations. We observed a greater variability among quasispecies associated with the 155 pathway, and IC(50) determinations showed that the fold resistance to raltegravir, relative to wild-type, was 10 for the N155H mutant and 50 for the G140S+Q148H mutant.
  
  
  CONCLUSIONS
  Clonal analysis strongly suggests that the two main genetic pathways, 155 and 148, involved in the development of resistance to raltegravir are independent and exclusive. Moreover, the switch of the resistance profile from 155 to 148 may be related to the higher level of resistance to raltegravir conferred by the 148 pathway and also to the higher instability of the 155 pathway.
authors.affiliation: UPMC Univ Paris 06, F-75005 Paris, France. isabelle.malet@psl.aphp.fr
authors.forename: Isabelle
authors.initials: I
authors.lastname: Malet
authors.forename: Olivier
authors.initials: O
authors.lastname: Delelis
authors.forename: Cathia
authors.initials: C
authors.lastname: Soulie
authors.forename: Marc
authors.initials: M
authors.lastname: Wirden
authors.forename: Luba
authors.initials: L
authors.lastname: Tchertanov
authors.forename: Philippe
authors.initials: P
authors.lastname: Mottaz
authors.forename: Gilles
authors.initials: G
authors.lastname: Peytavin
authors.forename: Christine
authors.initials: C
authors.lastname: Katlama
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Mouscadet
authors.forename: Vincent
authors.initials: V
authors.lastname: Calvez
authors.forename: Anne-Genevieve
authors.initials: AG
authors.lastname: Marcelin
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D019380:Anti-HIV Agents / Q000494:pharmacology / Q000627:therapeutic use*; D016000:Cluster Analysis; D024882:Drug Resistance, Viral; D005838:Genotype; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology*; D019427:HIV Integrase / Q000235:genetics; D015497:HIV-1 / Q000145:classification* / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D020128:Inhibitory Concentration 50; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D011760:Pyrrolidinones / Q000494:pharmacology / Q000627:therapeutic use*; D000068898:Raltegravir Potassium; D017422:Sequence Analysis, DNA
chemical_list: D019380:Anti-HIV Agents; D011760:Pyrrolidinones; D000068898:Raltegravir Potassium; D019427:HIV Integrase; C514801:p31 integrase protein, Human immunodeficiency virus 1