Impact of HCV 3.0 EIA relative to HCV 2.0 EIA on blood-donor screening.

BACKGROUND: In 1996, the Ortho HCV Version 3.0 ELISA Test System (HCV 3.0 EIA) was licensed in the United States for donor screening but was neither mandated nor universally implemented. Data from two studies comparing the differential performance of HCV 3.0 EIA and HCV 2.0 EIA are presented. The first study evaluated the differential performance in a cross-section of screened whole-blood donors after implementation of HCV 3.0 EIA; the second study evaluated the differential performance of HCV 3.0 EIA in plasma donors acutely infected with HCV, identified during routine Abbott HCV 2.0 EIA and HCV NAT (using Roche Ampliscreen plate assay) donor screening. STUDY DESIGN AND METHODS: The first study evaluated HCV 3.0 EIA repeat-reactive donations from four US blood centers, identified during the first 5 months of HCV 3.0 EIA implementation. HCV EIA repeat-reactive donations confirmed by RIBA HCV 3.0 SIA were retested using both Ortho HCV Version 2.0 ELISA Test System and Abbott HCV 2.0 EIA. All EIA-discordant donations were tested by polymerase chain reaction (PCR). In the second study, Abbott HCV 2.0 EIA-nonreactive, HCV PCR-positive donors were enrolled in a follow-up study in which the index and follow-up samples were re-evaluated by HCV 3.0 EIA. RESULTS: In the first study, of 292,459 donations, 501 (0.17%) confirmed HCV 3.0 EIA-reactive donations were identified; 15 (0.005%) were nonreactive by Ortho HCV 2.0 EIA and were all HCV RNA negative. In the second study, Ortho HCV 3.0 EIA retesting of Abbott HCV 2.0 EIA-nonreactive, RNA-positive index donations identified 16 (23%) as 3.0 EIA reactive. In 42 panels with a discordant time of seroconversion, HCV 3.0 EIA sero-conversion preceded HCV 2.0 EIA in all cases (p < 0.001). Two donors with HCV 3.0 EIA-reactive index donations never seroconverted by HCV 2.0 EIA during 160 to 180 days of follow-up. CONCLUSION: These studies demonstrate that HCV 3.0 EIA compared to HCV 2.0 EIA can better detect 1) remote nonviremic HCV infections, 2) acute infection, and 3) HCV antibodies in cases of atypical seroconversion.

Sensitivity of HCV RNA and HIV RNA blood screening assays.

BACKGROUND: The FDA requirement for sensitivity of viral NAT methods used in blood screening is a 95-percent detection limit of 100 copies per mL, whereas the NAT screening system should have a sensitivity of at least 5000 copies per mL per individual donation. According to the Common Technical Specifications of the European Directive 98/79/EC for in vitro diagnostics, viral standard dilutions (calibrated against the WHO standard) should be tested at least 24 times for a statistically valid assessment of the 95-percent detection limit. STUDY DESIGN AND METHODS: Viral standard dilution panels (PeliCheck, VQC-CLB) were prepared for HCV RNA genotypes 1 and 3 and for HIV RNA genotypes B and E. In a multicenter study, 23 laboratories tested the panels all together in 8 to 91 test runs per NAT method. RESULTS: The following 95-percent detection limits (and 95% CIs) were found on the HCV RNA genotype 1 reference panels (shown as geq/mL): Gen-Probe TMA, 85 (64-118); AmpliScreen, 126 (83-225); AmpliScreen with NucliSens Extractor, 21 (13-44); Amplicor with NucliSens Extractor, 69 (50-102), and Amplicor with Qiagen extraction technology, 144 (74-102). On HIV RNA genotype B dilution panels, the following 95-percent detection limits were found (shown as geq/mL): Gen-Probe TMA, 31 (20-52); AmpliScreen, 126 (67-311); AmpliScreen with NucliSens Extractor, 37 (23-69), and NucliSens QL assay, 123 (51-566). HIV RNA genotype E panels were detected with equal sensitivity as HIV RNA genotype B panels. In the Gen-Probe TMA assay, the 50-percent detection limits on HIV RNA type B and type E were 3.6 (2.6-5.0) and 3.9 (2.4-5.8) geq per mL, respectively. The HCV RNA genotype 1 and 3 standards were detected with equal sensitivity. CONCLUSION: The differences in sensitivity between NAT assays can be explained by the input of isolated viral nucleic acid in the amplification reactions. The FDA requirements for sensitivity of NAT blood screening assays can be met by the Gen-probe TMA, as well as by the AmpliScreen assays, particularly when combined with the NucliSens Extractor.