• anti-HBc assays;
  • anti-HBs;
  • blood screening;

Background and Objectives  Since voluntary introduction of hepatitis B virus (HBV) minipool nucleic acid amplification technology (NAT) at the German Red Cross, the expected residual risk of a transfusion-associated HBV infection has been estimated to be 1 : 500 000 – about 10 times higher than for human immunodeficiency virus (HIV) or hepatitis C virus (HCV) infection. Donors demonstrating chronic positivity for antibody to hepatitis B core antigen (anti-HBc), negativity for hepatitis B surface antigen (HBsAg) and polymerase chain reaction (PCR)-negative with a low virus load are a major cause of this increased risk.

Materials and Methods  Ten-thousand blood donors from our blood-donation centre were screened for anti-HBc using the current PRISM® HBc and the new PRISM® HBcore assay to evaluate the diagnostic sensitivity and specificity of these tests. PRISM® HBc- or PRISM® HBcore-reactive samples were further analysed using seven additional tests for anti-HBc, two tests for antibody to hepatitis B surface antigen (anti-HBs), one test for antibody to hepatitis B envelope antigen (anti-HBe) and three HBV NAT assays.

Results  From a total of 10 000 donors, nine and 14 samples were reactive only in the PRISM® HBc and the PRISM® HBcore, respectively, whereas 165 samples were reactive in both anti-HBc assays. Further analysis of these 188 anti-HBc-reactive specimens in a total of nine different anti-HBc assays revealed concordant results for 162 (86·2%) specimens. Sample cut-off values for anti-HBc were significantly (P < 0·01) lower for anti-HBc-only reactive samples compared with specimens that were also reactive for anti-HBs or anti-HBe.

Conclusions  Both PRISM anti-HBc assays revealed that ≈ 1·8% of non-prescreened blood donors from Germany were reactive for anti-HBc. Although sensitivity was comparable between both assays, specificity was increased significantly with the PRISM® HBcore. High anti-HBc sample cut-off values were indicative for reactivity in other HBV parameters and for concordant results in the nine different anti-HBc assays. Look-back investigations are necessary to estimate the infection risk both of anti-HBc-only positive and of anti-HBc/anti-HBs-positive blood transfusions.