title: Successful use of Plasma Preparation Tubes™ (PPTs) in the COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 test.
abstract: BACKGROUND
  Since switching to the COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) HIV-1 Test, v. 1.0 from the Amplicor HIV-1 Monitor Test, v. 1.5, an increase in detectable viral load results was noted. We were concerned that this was due to the use of Plasma Preparation Tubes (PPT) in this test.
  
  
  OBJECTIVE
  To assess the impact of different pre-analytical processing conditions on HIV-1 viral load results on the COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) HIV-1 Test.
  
  
  METHODS
  Sixty-three HIV-infected patients were consented and had 3 PPTs and 1 K2EDTA drawn for HIV-1 viral load testing. Three methods of PPT processing were compared against the referent K2EDTA tube which was spun at 1100 × g for 20 min, poured off and frozen; PPT1 was refrigerated with an additional centrifugation prior to testing, PPT2 was processed similarly to EDTA, and PPT3 was centrifuged, frozen and centrifuged again prior to testing.
  
  
  RESULTS
  PPT1 and PPT3 yielded results that were most similar to the referent EDTA processing, with a concordance correlation coefficient (CCC) of 0.80 and 0.85, compared to PPT2 with CCC of 0.37. Both PPT1 and PPT3 involved additional centrifugation prior to testing. In 26 patients with residual samples from the PPT2 processing, 9 (34.6%) were found to have the presence of proviral DNA, which likely contributed to the elevated HIV-1 RNA viral loads in these individuals.
  
  
  CONCLUSIONS
  PPTs can be used in the COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) HIV-1 Test with an additional centrifugation in order to avoid misleading elevated HIV-1 RNA viral loads that may change patient management.
authors: Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, USA. colleen.kraft@emory.edu
authors: Colleen S
authors: CS
authors: Kraft
authors: José Nilo G
authors: JN
authors: Binongo
authors: Eileen M
authors: EM
authors: Burd
authors: Molly E
authors: ME
authors: Eaton
authors: Cindy B
authors: CB
authors: McCloskey
authors: Helen
authors: H
authors: Fernandes
authors: Charles E
authors: CE
authors: Hill
authors: Angela M
authors: AM
authors: Caliendo
mesh_terms: D001800:Blood Specimen Collection / Q000295:instrumentation* / Q000379:methods; D015658:HIV Infections / Q000097:blood / Q000175:diagnosis / Q000821:virology*; D015497:HIV-1 / Q000235:genetics* / Q000302:isolation & purification*; D006801:Humans; D012367:RNA, Viral / Q000097:blood; D019562:Viral Load / Q000379:methods / Q000592:standards
chemical_list: D012367:RNA, Viral