hepatitis B core antigen (HBcAg)

Hepatitis B core antigen (HBcAg) is a protein found inside the hepatitis B virus. It appears in infected liver cells and helps the immune system recognize the virus. Because HBcAg is not typically found in the blood, testing for it indicates an active infection within the liver. Its presence suggests the virus is actively replicating, prompting the body’s immune response. Understanding HBcAg helps doctors determine the stage of infection and whether the virus is ongoing, guiding treatment decisions.