Screening of blood donors for human parvovirus B19 and characterization ofthe results

Background and Objectives: Human parvovirus B19 (B19 virus) can be transmit ted through blood transfusion and plasma-derived products. In a previous re port, we utilized the simple hemagglutination method based on the interacti on between the B19 virus and P antigen on human erythrocytes in order to sc reen the blood donors. We called this method receptor-mediated hemagglutina tion (RHA) [Lancet 1995;346:1237-1238]. In this paper, we report on a large -scale screening of the B19 virus by RHA and discuss the results. Materials and Methods: Donor sera from September 1995 to March 1997 and seroconversi on panels were enrolled. Donor sera were examined by RHA for large-scale sc reening. The positive sera in the first screening were then further investi gated by the RHA inhibition test, countercurrent immunoelectrophoresis (CIE ), an enzyme-linked immunosorbent assay, and polymerase chain reaction (PCR ). We also evaluated the infectivity and neutralizing activity of various k inds of sera by the erythroid colony forming unit (CFU-e) assay. To examine the detection limits of the B19 virus by RHA, B19-viremic sera were purifi ed by sucrose gradient ultracentrifugation. Results: Among 257,710 sera spe cimens, 293 sera (0.11%) gave a positive reaction in the first screening us ing RHA. Out of these 293 sera specimens, 31 were positive for PCR, of whic h 28 were also RHA inhibition-positive, and 25 of the 28 CIE-positive. In t he CFU-e injury assay, all the RHA inhibition (+) sera showed a decrease in the number of erythroid colonies. The RHA inhibition (-) PCR (+) B19 antib ody (+) sera did not affect the erythroid colony formation and protected CF U-e from injury by the B19 virus. By measuring the amount of purified B19 p rotein and its RHA titer, the detection limit of the B19 virus by RHA was c alculated to the 0.37+/-0.03 ng/ml. Conclusion: These results suggest that the RHA(+) RHA inhibition (+) sera were infectious in vitro. The combinatio n of RHA and the RHA inhibition test is considered to be useful for the lar ge-scale screening of infectious B19 virus in blood donors with high specif icity.