title: Performance Evaluation of the New HIV-1 Quantification Assay, Xpert HIV-1 Viral Load, on a Wide Panel of HIV-1 Variants.
abstract: To evaluate the quantification performance of the new Cepheid GeneXpert HIV-1 viral load assay, on a wide panel of HIV-1 variants.
  
  
  
  Clinical performance was evaluated relative to the Abbott RealTime HIV-1 assay on 285 HIV-1 seropositive samples selected to cover the assays quantification range (40 copies/mL-10,000,000 copies/mL), and included RNA undetectable or detected seropositive samples. The panel comprised 120 subtype B, 150 non-B, and 15 nontypable clinical samples; serial dilutions of 18 viral supernatants representative of the divergent viruses of HIV-1 groups N, O, and P were also tested.
  
  
  
  Based on samples selected according to the Abbott assay viral loads (VL), the Cepheid assay detected or quantified 222/285 (78%) samples and the Abbott assay 240/285 (84%). Xpert yielded VLs for 162 (76%) of the 213 quantifiable samples with Abbott. This difference corresponded to 51 samples with VL >40 copies/mL by the Abbott assay (all below 200 copies/mL) but detected (n = 40) or undetectable (n = 11) by the Cepheid assay. VL of samples quantifiable by both assays (n = 162) showed very strong correlation, with a Spearman correlation coefficient of 0.985 and a Bland-Altman's mean of differences of -0.01. Performance for quantification of the non-M samples showed very good correlation, with significantly higher values with Cepheid for the group N and 2 group O samples.
  
  
  
  Our study showed that the Xpert HIV-1 VL assay offered very good performance for detection and quantification of the current HIV-1 genetic diversity; differences reported at the threshold could be an issue and requires further evaluations. The practicability of this new assay makes it suitable for low-income countries, where it could facilitate and improve follow-up of patients, as well as for high-income regions.
authors.affiliation: *Laboratoire de Virologie Associé au Centre National de Référence du VIH, Département de Microbiologie, Hôpital Charles Nicolle, CHU de Rouen, Rouen, France; †GRAM, Equipe d'Accueil 2656, Faculté de Médecine-Pharmacie, Institut de Recherche et d'Innovation en Biomédecine, Université de Rouen, Rouen, France; and ‡COREVIH Haute-Normandie, Hôpital Charles Nicolle, CHU de Rouen, Rouen, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Gueudin
authors.forename: Adeline
authors.initials: A
authors.lastname: Baron
authors.forename: Elodie
authors.initials: E
authors.lastname: Alessandri-Gradt
authors.forename: Véronique
authors.initials: V
authors.lastname: Lemée
authors.forename: Thomas
authors.initials: T
authors.lastname: Mourez
authors.forename: Manuel
authors.initials: M
authors.lastname: Etienne
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Plantier
mesh_terms: D014644:Genetic Variation; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000235:genetics* / Q000302:isolation & purification*; D006801:Humans; D012367:RNA, Viral / Q000235:genetics; D011933:Reagent Kits, Diagnostic / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019562:Viral Load
chemical_list: D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic