title: Pitfalls of HIV genotypic tropism testing after treatment interruption.
abstract: OBJECTIVE
  The genotypic method is reliable enough for the determination of tropism and largely preferred in Europe. However, careful interpretation is essential when assessing HIV genotypic resistance during treatment interruption (TI) due to the possible disappearance of resistant strains. The results of HIV genotypic tropism testing in such a context remain unknown.
  
  
  METHODS
  First, we studied changes in tropism in patients included in a structured TI assay: the Reverse study. Second, we investigated the unexpected tropism switches from X4 to R5 recorded in our routine database.
  
  
  RESULTS
  Tropism determination was possible in 21 patients of the Reverse study, 9 of whom had an X4 virus (43%) at baseline. Two patients displayed a change of tropism during TI, both switching from X4 to R5. Regarding the database investigation, 7 of the 222 patients with at least two plasma tropism determinations recorded in the database displayed a switch from X4 to R5. TI due to non-compliance at the time of the tropism change was reported for five of these seven patients.
  
  
  CONCLUSIONS
  We have shown that the redistribution of the HIV population caused by TI could potentially result in X4 viruses becoming undetected and inappropriate prescription of a CCR5 receptor antagonist. Therefore, genotypic tropism results should be interpreted with caution in such a context.
authors.affiliation: Université Pierre et Marie Curie, Paris 6, France. marc.wirden@psl.aphp.fr
authors.forename: Marc
authors.initials: M
authors.lastname: Wirden
authors.forename: Cathia
authors.initials: C
authors.lastname: Soulié
authors.forename: Slim
authors.initials: S
authors.lastname: Fourati
authors.forename: Marc Antoine
authors.initials: MA
authors.lastname: Valantin
authors.forename: Anne
authors.initials: A
authors.lastname: Simon
authors.forename: Nadine
authors.initials: N
authors.lastname: Ktorza
authors.forename: Roland
authors.initials: R
authors.lastname: Tubiana
authors.forename: Manuela
authors.initials: M
authors.lastname: Bonmarchand
authors.forename: Luminita
authors.initials: L
authors.lastname: Schneider
authors.forename: Vincent
authors.initials: V
authors.lastname: Calvez
authors.forename: Christine
authors.initials: C
authors.lastname: Katlama
authors.forename: Anne-Genevieve
authors.initials: AG
authors.lastname: Marcelin
mesh_terms: D019380:Anti-HIV Agents / Q000494:pharmacology / Q000627:therapeutic use; D016208:Databases, Factual / Q000639:trends; D005838:Genotype; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D015497:HIV-1 / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D016896:Treatment Outcome; D056189:Viral Tropism / Q000187:drug effects* / Q000502:physiology*
chemical_list: D019380:Anti-HIV Agents