1. PROFICIENCY TESTING OF IN-HOUSE NAT ASSAYS USED FOR BLOOD SCREENING XXI SoGAT International Working Group Meeting on the Standardization of NAT for the Safety Testing of Blood, Tissues and Organs for Blood-Borne Pathogens 28 - 29 May 2009 Brussels, Belgium Paul-Ehrlich-Institut, Langen, Germany WHO Collaborating Centre for Quality Assurance of Blood Products and in vitro Diagnostic Devices Julia Kreß Michael Chudy Micha Nübling

2. 1 German Regulations for NAT Blood Donor Screening  1999: first mandatory NAT was introduced for HCV (< 5.000 IU/mL ID)  2004: NAT was implemented for HIV-1 (< 10.000 IU/mL ID)  HBV NAT is voluntarily performed by many blood donation services  in-house developed NAT assays, CE-marked diagnostic assays (off- label-use) and CE-marked NAT screening assays may be used  assays are validated for the individual pool size (10 to 96 donations)  validation studies are assessed by PEI  NAT systems undergo regular external quality assessment programs organised by PEI  2008: proficiency study for in-house NAT assays: HCV, HIV-1 and HBV

3. 2 In-house NAT Proficiency Study 2008: Objective  verification of the efficiency of in-house NAT assays for the detection of HCV, HIV-1 and HBV in blood donations regarding  analytical sensitivity  genotype / subtype sensitivity  specificity  reproducibility  the participation in the proficiency study is mandatory for HCV and HIV-1 NATs, voluntary for HBV NAT

4. 3 In-house NAT Proficiency Study 2008: Study Design  detection limit of the HCV, HIV-1 and HBV NATs with respect to the pool size  testing panels: calibrated PEI reference preparation, two positive materials and negative plasma  HIV-1-samples: one missed by CTM v1, one with discrepant results  0.5 log dilution series starting with the required minimum sensitivity  characterization of panels by CE-certified NAT screening systems: cobas TaqScreen MPX Test, Procleix Ultrio Assay  dilution of samples individually for each lab simulating the pool size  encoding of labs and samples  sample shipment on dry ice  submission of qualitative results (reactive / non-reactive)

5. 4 In-house NAT Proficiency Study 2008: Participants  Invited laboratories:  in-house NAT screening assays (non-CE-marked / CE-marked)  CE-marked diagnostic assays used for screening (off-label-use)  CE-marked screening system with large pool sizes (48, 96)  HCV: 30 labs 16 in-house NATs, 16 diagnostic assays, 3 cobas TaqScreen MPX (5 labs: 2 different methods)  HIV-1: 30 labs 15 in-house NATs, 15 diagnostic assays, 3 cobas TaqScreen MPX (3 labs: 2 different methods)  HBV: 21 labs 14 in-house NATs, 6 diagnostic assays, 3 cobas TaqScreen MPX (2 labs: 2 different methods)

6. 5 In-house NAT Proficiency Study 2008: HCV Results

7. 6 In-house NAT Proficiency Study 2008: HIV-1 Results

8. 7 In-house NAT Proficiency Study 2008: HBV Results

9. 8 In-house NAT Proficiency Study 2008: Conclusion  all participants meet the PEI sensitivity requirements  in most labs NAT assays show higher sensitivity than required  high specificity: only 1 false-positive result by 1 lab  HIV-1: CTM v1-missed sample was detected by other systems  due to high mutation rates there is a certain amount of risk that infectious donations are missed by HIV-1 NATs  voluntary HBV NAT assays: high sensitivity and specificity  in-house NAT systems and off-label-use systems under proper conditions are still suitable for blood donor screening