Antibody to hepatitis B core antigen.

Two distinct antigen-antibody systems are associated with the hepatitis B virus (HBV): hepatitis B surface antigen (HBs Ag) and antibody (anti-HBs) and the more recently described hepatitis B core antigen (HBc Ag) and antibody (anti-HBc). Testing of serial serum samples from patients with type B hepatitis demonstrates the regular occurrence of anti-HBc during the course of this disease. In general, highest titers of anti-HBc are seen with prolonged circulation of HBs Ag as in the chronic carrier state. Titers of anti-HBc begin to fall with recovery from HBV infection and anti-HBc appears to be shorter lived than anti-HBs. As such, anti-HBc testing is important in documenting the occurrence of infection with HBV and is of great value in epidemiologic studies and in evaluating the safety and efficacy of hepatitis B immune globulin and HBV vaccines.