Yield of HCV and HIV-1 NAT after screening of 3.6 million blood donations in central Europe.

BACKGROUND: HCV and HIV-1 NAT of all blood donations was initiated at our institutions in January 1997 to reduce the residual risk of transfusion-transmitted virus infections. The yield of NAT after testing more than 3.6 million donations in central Europe is reported. STUDY DESIGN AND METHODS: Automated pipetting instruments were used to pool up to 96 donor samples including those that were antibody reactive. To compensate for dilution of the individual donor samples by pooling, viruses were enriched from the pools by centrifugation at 48,000 x g. A commercial PCR (Cobas Amplicor, Roche) and an in-house PCR were applied for HCV and HIV-1 amplification, respectively. RESULTS: Six HCV and 2 HIV-1 PCR confirmed-positive, antibody-negative donations (yield, 1 in 600,000 and 1 in 1.8 million, respectively) were identified. Thirty-nine and 11 multiple-time donors seroconverted for HCV and HIV, respectively, and look-back procedures were initiated. Archived samples from preseroconversion donations were thawed and retested by single-sample PCR and remained negative. The recipients of the blood components were traced and tested. All traced recipients were negative for HCV and HIV antibodies. CONCLUSION: The yield of NAT in central European Red Cross blood donors was less than expected from theoretical calculations for American and German multiple-time donors. Look-back procedures for HCV and HIV indicated that no donation given before seroconversion of the donor was missed by minipool PCR. Sensitivity of minipool PCR testing after virus enrichment seems to be sufficiently high to close the diagnostic window almost completely.

NAT for HBV and anti-HBc testing increase blood safety.

BACKGROUND: Routine HBV PCR screening of blood donations to our institutes was introduced in January 1997 to complete the NAT screening program for transfusion-relevant viruses. Testing was successively extended to customer transfusion services with a total of 1,300,000 samples tested per year. STUDY DESIGN AND METHODS: Minipools of 96 blood donation samples were formed by automatic pipettors. HBsAg-reactive samples were included. HBV particles were enriched from the minipools by centrifugation. Conventional and in-house TaqMan PCRs were successively applied for HBV amplification. Sensitivity reached 1000 genome equivalents per mL for each individual donation. Confirmatory single-sample and single-sample enrichment PCRs were established with sensitivities of 300 and 5 to 10 genome equivalents per mL, respectively. RESULTS: After screening of 3.6 million donor samples, 6 HBV PCR-positive, HBsAg-negative donations were identified. Two samples were from infected donors who had not seroconverted and four were from chronic anti-HBc-positive low-level HBV carriers. Retesting by single-sample PCR of 432 samples confirmed positive for HBsAg identified 37 donations that were negative in minipool PCR. Donor-directed look-back procedures indicated that no infected donor who had not yet seroconverted was missed by minipool PCR. However, recipient-directed look-back procedures revealed two anti-HBc-positive recipients of HBsAg-negative minipool PCR-negative, anti-HBc-positive and single-sample PCR-positive blood components. After testing randomly selected 729 HBsAg-negative minipool PCR-negative, anti-HBc-positive donors by single-sample enrichment PCR, 7 were identified with < or = 10 HBV particles per mL of donor plasma. CONCLUSION: Minipool PCR testing after virus enrichment was sensitive enough to identify HBsAg-negative donors who had seroconverterd and HBsAg-negative, anti-HBc-positive chronic HBV carriers. HBV NAT in conjunction with anti-HBc screening would reduce the residual risk of transfusion-transmitted HBV infection.