{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Hepatitis B virus (HBV), a member of the Hepdnavirus family, is spherical in shape with a diameter of 42 nm. It contains a 27 nm partially double-stranded DNA core enclosed within a lipoprotein coat. There are several important components of the virus: the surface antigen (HbsAg) is expressed on the outer membrane, the core antigen (HbcAg) is a component of the viral nucleocapsid, and the e antigen (HbeAg), a truncated derivative of core protein, serves as an indirect marker of virus replication."}]}]}