title: Evaluation of Xpert HIV-1 Qual assay for resolution of HIV-1 infection in samples with negative or indeterminate Geenius HIV-1/2 results.
abstract: BACKGROUND
  Diagnosis of HIV infection is a multistage algorithm. Following screening with 4(th) generation combination immunoassay, confirmation of HIV infection is performed with an antibody assay that differentiates HIV-1 from HIV-2 infection. In the newly updated algorithm, samples that are nonreactive or indeterminate in the differentiation assay are to be tested with an HIV-1 nucleic acid amplification (NAAT) test for resolution. Xpert HIV-1 Qual is a new NAAT assay approved for the identification of HIV infection in whole and dried blood.
  
  
  OBJECTIVE
  To assess the performance of Xpert HIV-1 Qual supplementary assay in resolving the clinical status of serum samples reactive by 4(th) generation immunoassays and indeterminate or negative by Geenius HIV-1/2 confirmatory assay.
  
  
  METHODS
  In a retrospective study, samples from 97 individuals for whom the true HIV-1 status was already known (by follow-up samples) and which were negative or indeterminate by HIV-1/2 Geenius assay were tested with Xpert Qual HIV-1 assay.
  
  
  RESULTS
  Xpert Qual assay correctly classified all 97 samples from HIV-1 positive (n=49) and negative (n=48) individuals. The sensitivity and specificity of Xpert Qual when using the true HIV status as a reference were 100% (92.7-100% at 95% confidence interval [CI] and 92.6-100% at 95% CI, respectively).
  
  
  CONCLUSIONS
  Applying Xpert Qual HIV-1 assay in the new HIV multi-stage diagnostic algorithm correctly classified 100% of HIV-1 infections including 49 from HIV-1 carriers who have not yet seroconverted. With this assay the total time required for acute HIV diagnosis could be significantly reduced.
authors.affiliation: National HIV Reference Laboratory, Central Virology Laboratory, Ministry of Health, Tel-Hashomer, Ramat-Gan, Israel.
authors.forename: Michal
authors.initials: M
authors.lastname: Michaeli
authors.affiliation: National HIV Reference Laboratory, Central Virology Laboratory, Ministry of Health, Tel-Hashomer, Ramat-Gan, Israel.
authors.forename: Marina
authors.initials: M
authors.lastname: Wax
authors.affiliation: National HIV Reference Laboratory, Central Virology Laboratory, Ministry of Health, Tel-Hashomer, Ramat-Gan, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Gozlan
authors.affiliation: National HIV Reference Laboratory, Central Virology Laboratory, Ministry of Health, Tel-Hashomer, Ramat-Gan, Israel.
authors.forename: Aviya
authors.initials: A
authors.lastname: Rakovsky
authors.affiliation: National HIV Reference Laboratory, Central Virology Laboratory, Ministry of Health, Tel-Hashomer, Ramat-Gan, Israel; Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Ella
authors.initials: E
authors.lastname: Mendelson
authors.affiliation: National HIV Reference Laboratory, Central Virology Laboratory, Ministry of Health, Tel-Hashomer, Ramat-Gan, Israel. Electronic address: orna.mor@sheba.health.gov.il.
authors.forename: Orna
authors.initials: O
authors.lastname: Mor
mesh_terms: D015492:AIDS Serodiagnosis; D000465:Algorithms; D015153:Blotting, Western; D015483:HIV Antibodies / Q000097:blood*; D015658:HIV Infections / Q000097:blood / Q000175:diagnosis* / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D015498:HIV-2 / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D007118:Immunoassay; D008403:Mass Screening; D021141:Nucleic Acid Amplification Techniques; D011933:Reagent Kits, Diagnostic; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D015483:HIV Antibodies; D011933:Reagent Kits, Diagnostic
keywords: Geenius; HIV-1 Qual; HIV-1/2 infection; NAAT; Xpert