The Isolated Anti-HBc Reactivity: New Developments/Die Bedeutung des isoliert anti-HBc positiven Befundes: neue Aspekte

Abstract

The presence of isolated antibody to hepatitis B virus (HBV) core antigen (anti-HBc) is the most frequent so-called unusual seroconstellation observed in HBV serology. Its clinical significance is still relatively unclear. In the last decade, its diagnostic significance has been intensively investigated. Actually, false positive results can be excluded through adequate confirmatory testing. Isolated anti-HBc reactivity is generally observed after resolved HBV infection (loss of anti-HBs or low-level anti-HBs). This serological pattern is also very frequently associated with HBsAg negative chronic low-level HBV DNA carriage. The reasons for the absence of HBsAg detection are inhibition of expression by HCV co-infection, and/or low-level HBsAg synthesis under the limit of detection of screening assays, presence of immune complexes and probably also in a minority of cases, HBsAg mutants. While anti-HBc screening of blood donations might further reduce the HBV related residual risk, it is not used worldwide because of its relatively poor cost-effectiveness and the burden of exclusion of donors through non-specific test results. Combined anti-HBc/HBsAg testing with a highly sensitive and specific assay is probably technically achievable and would permit to detect the rare cases of HBV DNA negative potentially infectious donations at a reasonable financial burden.