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SoGAT 24-05-2005 24 May 2005 Are conversion factors to international units assay related? Marco Koppelman, Henk Reesink, Nico Lelie, Theo Cuypers
SoGAT 24-05-2005
24 May 2005
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
Generic silica extraction‘Boom’ Technology
Cobas AmplicorNuclisens
SoGAT 24-05-2005
Procleix Ultrio HIV-1, HCV, and HBV
ResultsLuminometer
DetectionWater bath
TMAWater baths
PipettingTECAN 2
SampleProcessing
TCS
Specific Capture of Target
SoGAT 24-05-2005
AmpliPrep TNAI Cobas AmpliScreen HIV/HCV/HBV
Generic magnetic silica extraction
AmpliPrep Cobas Amplicor
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)
IU/mL Multi-Prep
Ampli-Prep
Ultrio
n=24 n=24 n=63
40 100% 100% 100 %
20 100 % 100 % 100 %
10 100 % 100 % 98 %
5 90 % 96 % 76 %
2.5 86 % 71 % 58 %
1.25 71 % 50 % 27 %
0.63 33 % 46 % 13 %
0.31 36 % 13 % 6 %
0.16 9 % 13 % 8 %
0.08 0 % 0 % 0 %
log (dilution)
50%
% positive
log (dilution)
50%
% positive
log (dilution)
50%
% positive
SoGAT 24-05-2005
Analytical Sensitivity Procleix Ultrio test*
Reference material
50% detection limit 95% detection limit
WHO-IS N1 IU/mL 95%CI IU/mL 95% CI HIV-1 IS2 48 3.4 2.4 - 4.7 26 16 - 58 HCV IS 63 0.9 0.7 - 1.0 4.6 3.7 - 6.5 HBV IS 63 1.9 1.5 - 2.6 11 7.3 - 22 PeliCheck ref. panel
N geq/mL 95%CI geq/mL 95%CI
PeliCh. HIV-1 48 5.7 4.3 - 7.6 65 41 - 119 PeliCh. HCV 48 13 9.0 - 20 86 50 - 204 PeliCh. HBV 48 34 26 - 44 328 213 - 586 1 Number of repeats per dilution 2 Discriminatory HIV-1 test
*Multicenter study; Assal (BC-Tours), Chudy (PEI), Garcia de Villaescusa (BC-Madrid),
Koppelman (Sanquin). Transfusion in press.
SoGAT 24-05-2005
0 2 4 6 8log (dilution)
Conversion Factor between two data-sets
95%
50%
% positivePotency calculated with SPSS
SoGAT 24-05-2005
Conversion factors IU to Geq
AmpliScreen
WHO
studies Ultrio1 AmpliPrep2 MultiPrep2 AmpliCor3
HIV-1 1 1.7 (1.2-4.3) 1.6 (0.9-2.7) - -
HCV 3.8 17.0 (5.8-84) 9.4 (3.3-43) - 5.1 (3.1-9.1)
HBV 7.4 20.7 (9.1-60) 12.5 (5.4-40) 11.0 (4.9-33) -
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
Standard Nucleic acid extraction
method 50% limit of detection 95% limit of detection
HBV-IS AmpliPrep 1.0 IU/mL (0.7-1.3) 6.7 IU/mL (4.3-13) MultiPrep 0.7 IU/mL (0.5-1.0) 5.2 IU/mL (3.3-10) MultiPrepa 1.3 IU/mL (0.9-1.7) 5.5 IU/mL (4.0-10) HCV-IS AmpliPrep 2.9 IU/mL (1.7-5.5) 23 IU/mL (11-106) MultiPrepa 7.3 IU/mL (2.2-10) 29 IU/mL (21-86) HIV-1-IS AmpliPrep 18 IU/mL (13-26) 187 IU/mL (108-422) MultiPrepa 22 IU/mL (13-29) 78 IU/mL (60-137) HBV-PeliCheck AmpliPrep 12 geq/mL (8.2-18) 123 geq/mL (68-301) MultiPrep 8.2 geq/mL (5.4-13) 101 geq/mL (52-295) MultiPrep 8.0 geq/mL (6.0-13) 100 geq/mL (55-291) HCV-PeliCheck AmpliPrep 36 geq/mL (17-65) 289 geq/mL (142-1061) MultiPrepb 9.9 geq/mL (6.3-15) 77 geq/mL (43-203) HIV-1-PeliCheck AmpliPrep 28 geq/mL (20-41) 183 geq/mL (108-434) MultiPrepb 6.6 geq/mL (4.4-10) 92 geq/mL (49-238) a data from kit insert. b data from Lelie et al. Transfusion et al. 2002; 42: 527-536.
SoGAT 24-05-2005
Conversion factors IU to Geq
AmpliScreen
WHO
studies Ultrio1 AmpliPrep2 MultiPrep2 AmpliCor3
HIV-1 1 1.7 1.6 - -
HCV 3.8 17.0 9.4 - 5.1
HBV 7.4 20.7 12.5 11.0 -
1Koppelman et al. Transfusion 2005 in press.
2Koppelman et al. 2005 Submitted.
3Cuypers et al.; Biologicals. 1999 27 303-14.
