title: Prevalence of R5 and X4 HIV variants in antiretroviral treatment experienced patients with virologic failure.
abstract: BACKGROUND
  Antiretroviral therapy (ART) inhibits virus replication. Nevertheless, ART has the disadvantage of generate selective resistance and adverse events. Coreceptor antagonists are a family of antiretroviral drugs that are used with the prior knowledge of patients HIV tropism.
  
  
  OBJECTIVE
  The purpose of this work was to estimate the prevalence of R5 and X4 variants among Chilean patients under antiretroviral therapy and virological failure and investigate variables such as plasma viral load (pVL) and CD4 cell count in the population studied.
  
  
  METHODS
  HIV RNA or proviral DNA was extracted from 454 consecutives patients and tropism testing was performed using a genotypic method performed with Geno2pheno setting a cutoff value for FPR 5.75%.
  
  
  RESULTS
  Among 454 individuals analyzed, 299 (66%) harbouring exclusively R5 variants. They not displayed a better clinical profile than individuals harbouring X4 strains (22%). For R5 patients the median of pVL and CD4 cell count were 268,000copies/mL, and 223cells/μL respectively. For X4 samples the values were 368,000copies/mL and 214cells/μL [P>0.05]). Only, 53 patients (12%) could not be analyzed and were categorized as non-reportable.
  
  
  CONCLUSIONS
  The genotypic method confirmed that R5 strains were more prevalent despite the fact that patients were treatment-experienced for several years. The genotypic strategy proved to be a faster and cost-effective option as compared to phenotypic assays. According to our results, two of every three patients under antiretroviral therapy and with virologic failure harbour R5 strains, and may be candidates for use of a CCR5 antagonist.
authors.affiliation: Laboratorio de Medicina Molecular, Hospital Clínico Universidad de Chile, Santiago, Chile. Electronic address: pferrer40@gmail.com.
authors.forename: P
authors.initials: P
authors.lastname: Ferrer
authors.affiliation: Centro de Biotecnología Acuícola, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile. Electronic address: mario.tello@usach.cl.
authors.forename: M
authors.initials: M
authors.lastname: Tello
authors.affiliation: Laboratorio de Infectología y Virología Molecular, División de Pediatría, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile. Electronic address: lmonteci@med.puc.cl.
authors.forename: L
authors.initials: L
authors.lastname: Montecinos
authors.affiliation: Laboratorio de Medicina Molecular, Hospital Clínico Universidad de Chile, Santiago, Chile. Electronic address: rociotorde@gmail.com.
authors.forename: R
authors.initials: R
authors.lastname: Tordecilla
authors.affiliation: Laboratorio de Medicina Molecular, Hospital Clínico Universidad de Chile, Santiago, Chile. Electronic address: consuefrm@gmail.com.
authors.forename: C
authors.initials: C
authors.lastname: Rodríguez
authors.affiliation: Departamento de Infectología, Complejo Asistencial Barros Luco. Facultad de Medicina, Universidad de Santiago de Chile, and Chilean AIDS Cohort (ChiAC), Santiago, Chile. Electronic address: cabel@vtr.net.
authors.forename: C
authors.initials: C
authors.lastname: Beltrán
authors.affiliation: Laboratorio de Medicina Molecular, Hospital Clínico Universidad de Chile, Santiago, Chile. Electronic address: ascalita@gmail.com.
authors.forename: M A
authors.initials: MA
authors.lastname: Guzmán
authors.affiliation: Laboratorio de Infectología y Virología Molecular, División de Pediatría, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile. Electronic address: mferres@med.puc.cl.
authors.forename: M
authors.initials: M
authors.lastname: Ferrés
authors.affiliation: Laboratorio de Infectología y Virología Molecular, División de Pediatría, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile. Electronic address: cape@med.puc.cl.
authors.forename: C M
authors.initials: CM
authors.lastname: Pérez
authors.affiliation: Laboratorio de Medicina Molecular, Hospital Clínico Universidad de Chile, Santiago, Chile. Electronic address: aafani@vtr.net.
authors.forename: A
authors.initials: A
authors.lastname: Afani
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D023241:Antiretroviral Therapy, Highly Active; D001483:Base Sequence; D018791:CD4 Lymphocyte Count; D005260:Female; D005838:Genotype; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000235:genetics; D015658:HIV Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000821:virology*; D015497:HIV-1 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics; D015995:Prevalence; D019713:Receptors, CCR5 / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000378:metabolism; D015728:Receptors, HIV / Q000378:metabolism; D017211:Treatment Failure; D016896:Treatment Outcome; D019562:Viral Load; D056189:Viral Tropism; D055815:Young Adult
chemical_list: D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments; D019713:Receptors, CCR5; D019718:Receptors, CXCR4; D015728:Receptors, HIV
keywords: AIDS; CCR5; Coreceptors; HIV; Maraviroc; Tropism