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Are conversion factors to international units assay related?. Marco Koppelman, Henk Reesink, Nico Lelie, Theo Cuypers. NAT test system for comparison. NucliSens Extraction Cobas Amplicor HCV Procleix Ultrio (Chiron/Gen-Probe) HIV-1, HCV, and HBV Multiprep Cobas AmpliScreen HBV
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Are conversion factors to international units assay related? Marco Koppelman, Henk Reesink, Nico Lelie, Theo Cuypers SoGAT 24-05-2005
NAT test system for comparison • NucliSens Extraction Cobas Amplicor HCV • Procleix Ultrio (Chiron/Gen-Probe) HIV-1, HCV, and HBV • Multiprep Cobas AmpliScreen HBV • AmpliPrep TNAI Cobas AmpliScreen HIV vrs 1.5 • AmpliPrep TNAI Cobas AmpliScreen HCV vrs2.0 • AmpliPrep TNAI Cobas AmpliScreen HBV SoGAT 24-05-2005
NucliSens Extraction Cobas Amplicor HCV Cobas Amplicor Nuclisens Generic silica extraction ‘Boom’ Technology SoGAT 24-05-2005
Procleix Ultrio HIV-1, HCV, and HBV Pipetting TECAN 2 Sample Processing TCS Detection Water bath TMA Water baths Results Luminometer Specific Capture of Target SoGAT 24-05-2005
AmpliPrep TNAI Cobas AmpliScreen HIV/HCV/HBV AmpliPrep Cobas Amplicor Generic magnetic silica extraction SoGAT 24-05-2005
Reference materials • Serial dilutions of the WHO International standards for: • HBV genotype A * (NIBSC 97/746) • HIV-1 genotype B* (NIBSC 97/656) • HCV genotype 1* (NIBSC 96/790) • *IU: Calibrated in WHO Collaborative Studies. • PeliCheck reference panels for • HBV genotype A# (S2184) • HIV-1 genotype B# (S2092) • HCV genotype 1# (S2088) • #Geq: Calibrated with Bayer bDNA SoGAT 24-05-2005
Analytical sensitivityWHO International Standard HBV DNA (97/746) SoGAT 24-05-2005
Analytical Sensitivity Procleix Ultrio test* *Multicenter study; Assal (BC-Tours), Chudy (PEI), Garcia de Villaescusa (BC-Madrid), Koppelman (Sanquin). Transfusion in press. SoGAT 24-05-2005
Conversion Factor between two data-sets Potency calculated with SPSS % positive 95% 50% 0 2 4 6 8 log (dilution) SoGAT 24-05-2005
Conversion factors IU to Geq 1Koppelman et al. Transfusion 2005 in press. 2Koppelman et al. 2005 Submitted. 3Cuypers et al.; Biologicals. 1999 27 303-14. SoGAT 24-05-2005
Conversion factors between IU and copies/ml are assay specific • Conversion factors of the WHO collaborative studies; the mean of different nucleic acid extraction techniques and amplification/detection systems (considerable interlaboratory variation) • Molecular composition of the reference material • Physical composition reference materials. Liquid versus lyophilized reference materials • Commutability of reference materials; knowledge of molecular characteristics of preparations is necessary • Preliminary conclusion: conversion factors from IU to VQC-geq assay specific SoGAT 24-05-2005
Conversion factor Dutch guilder to Euro What was the conversion factor between Euro and Guilder in 2001? It makes no difference! SoGAT 24-05-2005
Analytical Sensitivity AmpliScreen HIV-1/HCV/HBVAmpliPrep MultiPrep SoGAT 24-05-2005
Conversion factors IU to Geq 1Koppelman et al. Transfusion 2005 in press. 2Koppelman et al. 2005 Submitted. 3Cuypers et al.; Biologicals. 1999 27 303-14. SoGAT 24-05-2005