Hepatitis delta: the virus and the disease

Area of Science:

• Virology
• Molecular Biology
• Hepatology

Background:

• Hepatitis delta virus (HDV) shares biological and structural similarities with plant viroids and satellite RNA viruses.
• HDV RNA exhibits autocleavage and autoligation properties, characteristic of ribozymes, found in conserved domains homologous to viroids.
• The established pathobiology of delta hepatitis posits that HDV requires hepatitis B virus (HBV) for infection and is highly pathogenic.

Purpose of the Study:

• To investigate the role of HDV in latent infections and its interaction with HBV.
• To explore a potential third pathobiological mechanism for delta hepatitis development.

Main Methods:

• Analysis of biological and structural properties of HDV RNA.
• Investigation using a liver transplantation model to study HDV infection dynamics.
• Observation of disease reactivation upon HBV reintroduction in the liver graft.

Main Results:

• HDV RNA possesses catalytic properties, identifying it as the first mammalian ribozyme.
• Evidence suggests HDV can establish latent, asymptomatic infections independent of HBV.
• Disease reactivation in the liver transplantation model occurred only after HBV superinfection of a latent HDV state.

Conclusions:

• HDV RNA functions as a ribozyme, highlighting a link between plant and mammalian RNA viruses.
• HDV may establish latent infections without requiring HBV co-infection.
• HBV superinfection of a latent HDV infection represents a novel and significant pathobiological mechanism for delta hepatitis.