Clinical Significance

The hepatitis B virus consists of an outer envelope containing host-derived lipids and all S gene polypeptides, the large (L), middle (M), and small (S) surface proteins, also known as pre-S1, pre-S2 and HBsAg. The nucleocapsid contains core proteins HBcAg, a 3.2 kb, circular, partially double stranded viral DNA genome, an endogenous DNA polymerase (reverse transcriptase) enzyme, and protein kinase activity. The hepatitis core antigen comprises 183-185 amino acids.

During an infection with the hepatitis B virus, antibodies to HBcAg are generally formed, which often persist for life. Anti-HBc appears shortly after the onset of infection with hepatitis B virus and can usually be detected in serum soon after the appearance of HBsAg. Anti-HBc antibodies persist both in persons who have recovered from a hepatitis B infection and in those who develop HBsAg-carrier status. Accordingly, they are an indicator of existing or past hepatitis B infection.

In rare cases, an HBV infection can also run its course without the appearance of immunologically detectable anti-HBc (usually in immunosuppressed patients).

Due to the long persistence of anti-HBc following a hepatitis B viral infection, screening for HBV infection may be accompanied by testing for the presence of hepatitis B core antibodies as long as those who test positive are further tested for both HBsAg and anti-HBs to differentiate infection from immunity.

_{Source: Roche cobas Elecsys Anti-HBc II method sheet, V 2.0 2023-06}