Description
Hepatitis B virus (HBV) is an enveloped, double-stranded DNA virus belonging to the Hepadnaviridae family and is recognized as the major cause of blood transmitted hepatitis together with hepatitis C virus (HCV). Infection with HBV induces a spectrum of clinical manifestations ranging from mild, inapparent disease to fulminant hepatitis, severe chronic liver diseases, which in some cases can lead to cirrhosis and carcinoma of the liver. Classification of a hepatitis B infection requires the identification of a number of serological markers expressed during three phases (incubation, acute and convalescent) of the infection. Now several diagnostic tests are used for screening, clinical diagnosis and management of the disease. Hepatitis B "core" antigen (HBcAg) is a major component of the viral structure. HBcAg is composed of a single polypeptide of about 17 kD that is released upon disaggregation of the core particles; the antigen contains at least one immunological determinant. Antibodies to HBcAg (anti-HBc total antibody, and IgM) appear shortly after the appearance of HBsAg and persist for life both in persons who have recovered from a hepatitis B infection and in those who develop HBsAg-carrier status but in rare cases, a HBV infection can also run its course without the appearance of immunologically detectable anti-HBc (usually in immunosuppressed patients). Anti-HBc is a marker of acute, chronic or resolved HBV infection and screening for anti-HBc provides with information on the prevalence of the disease in different groups. In clinical diagnosis, the detection of anti-HBc is an important diagnostic marker and together with other hepatitis B test permits the diagnosis and management of the disease. In the absence of other hepatitis B markers (HBsAg-negative persons), anti-HBc may be the only indication of an existing hepatitis B viral infection