Hepatitis D virus is hepatotropic. Replication within hepatocytes results in cytotoxicity and direct liver damage. Hepatocellular necrosis and inflammation that occurs as result of HDV infection present similarly to the pathology of other acute and chronic viral hepatitis.
Direct pathogenesis of HDV is poorly understood and controversy exists over the direct pathogenic effects of the virus on the liver versus immune-mediated liver damage.
Both cellular and humoral immunity are induced by HDV co-infection and super infection. Antibodies are produced against HDV antigens and Hepatitis B virus surface antigens because HbsAg is the external antigen & viral attachment protein for HDV.
Re-infection with HDV have yet to be reported, which suggests some form of immunity after resolution of acute infection.
FIGURE from Fields Virology, 5th ed, 3039. Acute hepatitis D progressing to chronic hepatitis B virus infection.