Serum hepatitis B surface antigen

Hepatitis B virus surface antigen (HBsAg) refers to the small spherical particles and tube-shaped particles contained in the shell part of the hepatitis B virus. It is now divided into eight different subtypes and two mixed subtypes. Hepatitis B virus surface antigen appears in the blood circulation of patients at the early stage of hepatitis B virus infection and can last for months, years, or even life. However, during the window period of the so-called hepatitis B virus infection, the surface antigen of hepatitis B virus can be negative, and serological markers such as hepatitis B virus core antibodies can be positive.