title: Cobas ampliprep/cobas TaqMan HIV-1 v2.0 assay: consequences at the cohort level.
abstract: BACKGROUND
  High-sensitive real-time PCR assays are routinely used to monitor HIV-1 infected subjects. Inter-assay discrepancies have been described at the low viral load (VL) end, where clinical decisions regarding possible virological rebound are based.
  
  
  METHODS
  A retrospective study was performed to analyze frequencies of viral blips after transition to the COBAS Ampliprep/COBAS TaqMan v2.0 HIV-1 assay (Taqman v2.0) in patients with prior undetectable VLs as measured with the Roche Cobas Ampliprep Amplicor HIV-1 Monitor Test, v1.5 (Amplicor) and was evaluated in comparison to a group of patients monitored with the Abbott Real-time HIV-1 assay (Abbott RT) during the same period of time.
  
  
  RESULTS
  85 of 373 patients with VLs below the limit of quantification with Amplicor had VLs >50 copies/mL after transition to the TaqMan v2.0 assay. Among these 74.1% had VLs ranging from 50-499 copies/mL, 22.9% had VLs >500 copies/mL. From 22 patients with initial Taqman v2.0 based VLs exceeding 500 copies/mL, 6 patients had VLs <20 copies/mL after novel VL measurement on a next visit. In our control group with VL quantification using the Abbott RT assay, only 1 patient became detectable and showed a VL of <40 copies/mL after new measurement.
  
  
  CONCLUSIONS
  Transition to the Taqman v2.0 assay was accompanied by an increase of quantifiable HIV-1 VLs in patients with long term viral suppression under antiretroviral therapy that might be attributed to technical shortcomings of the Taqman v2.0 assay. A high test variability at the low VL end but also beyond was observed, making meaningful clinical interpretation of viral blips derived from different assays difficult.
authors.affiliation: Department of Internal Medicine III, Paracelsus Medical University, Salzburg, Austria.
authors.forename: Ninon
authors.initials: N
authors.lastname: Taylor
authors.forename: Katharina
authors.initials: K
authors.lastname: Grabmeier-Pfistershammer
authors.forename: Alexander
authors.initials: A
authors.lastname: Egle
authors.forename: Richard
authors.initials: R
authors.lastname: Greil
authors.forename: Armin
authors.initials: A
authors.lastname: Rieger
authors.forename: Bruno
authors.initials: B
authors.lastname: Ledergerber
authors.forename: Hannes
authors.initials: H
authors.lastname: Oberkofler
mesh_terms: D023241:Antiretroviral Therapy, Highly Active; D015331:Cohort Studies; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology; D015497:HIV-1 / Q000235:genetics* / Q000302:isolation & purification*; D006801:Humans; D011933:Reagent Kits, Diagnostic; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D019914:Taq Polymerase / Q000378:metabolism*; D013997:Time Factors; D019562:Viral Load / Q000235:genetics
chemical_list: D011933:Reagent Kits, Diagnostic; D019914:Taq Polymerase
references.citation: J Virol Methods. 2013 Jan;187(1):1-5
references.pmid: 23098667
references.citation: Ann Intern Med. 1997 Jun 15;126(12):946-54
references.pmid: 9182471
references.citation: Clin Infect Dis. 2009 Jan 15;48(2):260-2
references.pmid: 19113986
references.citation: J Clin Microbiol. 2007 Oct;45(10):3436-8
references.pmid: 17715371
references.citation: BMC Infect Dis. 2012 Apr 24;12:100
references.pmid: 22530816
references.citation: J Clin Virol. 2006 Feb;35(2):197-200
references.pmid: 16253548
references.citation: JAMA. 2005 Feb 16;293(7):817-29
references.pmid: 15713771
references.citation: Clin Infect Dis. 2012 Mar 1;54(5):724-32
references.pmid: 22238167
references.citation: J Clin Microbiol. 2006 Aug;44(8):2963-6
references.pmid: 16891517
references.citation: Curr Opin HIV AIDS. 2006 Mar;1(2):157-61
references.pmid: 19372801
references.citation: J Acquir Immune Defic Syndr. 2007 Apr 15;44(5):500-5
references.pmid: 17259908
references.citation: J Acquir Immune Defic Syndr. 2009 May 1;51(1):3-6
references.pmid: 19247185
references.citation: J Clin Virol. 2012 Apr;53(4):354-5
references.pmid: 22261125
references.citation: J Acquir Immune Defic Syndr. 2010 Aug;54(4):442-4
references.pmid: 20611035
references.citation: Antivir Ther. 2009;14(8):1189-93
references.pmid: 20032549
references.citation: J Clin Microbiol. 2009 Apr;47(4):1238-40
references.pmid: 19193839
references.citation: Science. 1998 Jun 19;280(5371):1866-7
references.pmid: 9669944
references.citation: J Infect Dis. 2012 Apr 15;205(8):1230-8
references.pmid: 22438396
references.citation: J Clin Microbiol. 2011 Jan;49(1):292-7
references.pmid: 21068276
references.citation: Clin Infect Dis. 2005 Dec 1;41(11):1671-4
references.pmid: 16267742
references.citation: J Clin Microbiol. 2009 May;47(5):1543-5
references.pmid: 19297599
references.citation: J Clin Microbiol. 2009 Apr;47(4):889-95
references.pmid: 19193837
references.citation: J Clin Virol. 2006 Apr;35(4):420-5
references.pmid: 16604577
references.citation: Med Microbiol Immunol. 2013 Feb;202(1):67-75
references.pmid: 22699843
references.citation: J Clin Microbiol. 2009 Jul;47(7):2170-4
references.pmid: 19420166