Validation of the NucliSens Extractor in combination with the hepatitis C virus Cobas Amplicor 2.0 assay in four laboratories in the Netherlands utilizing nucleic acid amplification technology for blood screening.

BACKGROUND AND OBJECTIVES: Since July 1 1999, four laboratories in the Netherlands have been routinely screening plasma minipools for the release of labile blood components utilizing hepatitis C virus nucleic acid amplification technology (HCV NAT). This report describes the performance evaluation of the HCV NAT method and the quality control results obtained during 6 months of routine screening. MATERIALS AND METHODS: Plasma minipools of 48 donations were prepared on a Tecan Genesis robot. HCV RNA was isolated from 2 ml of plasma by using the NucliSens Extractor and amplified and detected with the Cobas HCV Amplicor 2.0 test system. For validation of the test system the laboratories used viral quality control (VQC) reagents of CLB. RESULTS: Initial robustness experiments demonstrated consistent detection of PeliSpy HCV RNA samples of 140 genome equivalents/ml (geq/ml) in each station of the installed Nuclisens Extractors. Further 'stress' tests with a highly viraemic sample of approximately 5 x 10(6) geq/ml did not contaminate negative samples processed on all Extractor stations in subsequent runs. In the validation period prior to July 1999, 1021 pools were tested with the following performance characteristics: 0.1%, initially false reactive; 0.89%, failure of internal control detection; 0.97%, no eluate generated by the Extractor; and 100% reactivity of the PeliSpy 140 geq/ml control in 176 Extractor runs and a 98% reactivity rate of the PeliSpy 38 geq/ml control in 102 test runs. By testing the PeliCheck HCV RNA genotype 1 dilution panels 49 times, an overall 95% detection limit of 30 geq/ml ( approximately 8 IU/ml) and a 50% detection limit of 5 geq/ml was found by the four laboratories. In the first 6 months of routine screening, the minimum requirement for invalid results (2%) was exceeded with some batches of silica and NucliSens Extractor cartridges. From November 1999 to February 2000, the manufacturer (Organon Teknika) improved the protocol for silica absorption of the Nuclisens Extractor -- the cartridge design as well as the software of the Extractor. During the next 6 months of observation in 2000, the percentages of false initial reactives and invalids were 0.05% and 1.4%, respectively, in 8962 pools tested. Of these invalid results, 0.74% and 0.66% were caused by Extractor failure and negative internal control signals, respectively. The PeliSpy HCV RNA 'stop or go' run control of 140 geq/ml was 100% reactive, but invalid in 16/1375 (1.2%) of cases. The PeliSpy run control of 38 geq/ml for monitoring sensitivity of reagent batches was reactive in 95% of 123 samples tested. CONCLUSIONS: Each of the four HCV NAT laboratories in the Netherlands have achieved similar detection limits that are well below the sensitivity requirements of the regulatory bodies. After improvement of the NucliSens Extractor procedure, the robustness of the test system has proved to be acceptable for routine screening and timely release of all labile blood components.

Risk factors and anti-HBc reactivity among first time blood donors.

BACKGROUND AND OBJECTIVES: The usefulness of testing for antibody to hepatitis B core antigen (anti-HBc) as a surrogate marker for non-A, non-B hepatitis can no longer be clearly established in the face of anti-hepatitis C virus testing. Application of anti-HBc testing in blood donors for detection of hepatitis B in addition to hepatitis B surface antigen testing (HbsAg) is a matter of debate. MATERIALS AND METHODS: We examined the serology and risk analysis data in a group of first-time blood donors. In 1.48% of 16,081 donors, anti-HBc reactivity was found. We invited a study group of 112 donors for extensive interviewing about the risk of blood transmissible diseases, and for serological testing. A control group of 240 first-time donors was studied as well. RESULTS: In the study group, the age was older (p < 0.001), a history of liver disease was more frequent (p < 0.001), and the donor (p < 0.001) or the donor's partner (p < 0.05) had either stayed longer in an HBV-endemic area or had been born in one. Combining these with the serological results, we found that strong anti-HBc reactivity was related to hepatitis B risk factors in HBsAg-negative donors. CONCLUSIONS: Anti-HBc testing in HbsAg-negative first-time donors makes it possible to identify hepatitis B risk factors with a prevalence of 0.02%. Our findings also stress the importance of including the history of the donor's partner(s) in the risk analysis before blood donation.

Intensification of donor interviewing procedures: a feasibility study.

OBJECTIVE: To determine the feasibility and acceptability for the blood donor of an intensified blood donor interviewing procedure on high-risk factors for infectious diseases. To answer the question whether an intensified blood donor interviewing procedure would lead to an unacceptable loss of blood donors. DESIGN: Feasibility study. SETTING: Red Cross Bloodbank Rotterdam. DONORS: Study group of 240 first-time donors. INTERVENTIONS: Intensified donor interviewing techniques by direct questioning and workload assessment. RESULTS: Intensified interviewing was welcomed by 88-91% of first-time donors and rejected by 2-5%. On the question whether the intensified interviewing procedure should be the standard approach of the blood bank the answer was positive in 76-82% of first-time donors and negative in 11-14%. No blood donors indicated that this would be a reason to withdraw from blood donation. The workload for the blood bank physician increased by approximately 30%. CONCLUSION: The approach of intensified donor interviewing techniques in first-time donors is acceptable both to the donors and the blood bank workload.