Hepatitis Delta Virus (HDV) infections always occur in association with hepatitis B virus (HBV) infections because of their dependence upon the HBV. The hepatitis delta virion is composed of an outer lipoprotein envelope made of the surface antigen of HBV (HBsAg) and an inner ribonucleoprotein structure in which the HDV genome resides. Due to the dependence of HDV on HBV, the presence of HBsAg is necessary for the diagnosis of HDV infection.HDV causes both acute and chronic infections. Asymptomatic and non-progressive illnesses are seen in a minority of cases, but a severe and progressive route to cirrhosis is present in most.