Acute and chronic hepatitis delta virus infection: direct or indirect effect on hepatitis B virus replication?

In a large population of patients, chronic hepatitis delta virus (HDV) infection was usually associated with absence of hepatitis B virus (HBV) replication. However, acute HDV superinfection progressing to chronic HDV infection in two hepatitis B e antigen (HBeAg)-positive HBV carriers and coinfection in two other patients who progressed to chronic HBV (HBeAg-positive) and HDV infection was associated with continuing high-level HBV replication for several years. Thus HDV infection does not always inhibit HBV replication. The hypothesis that the different effects of HDV coinfection and superinfection on HBV replication may stem from variability in the capacity of the host to produce and respond to interferon is discussed.