Identification and characterization of incomplete hepatitis A virus particles

Area of Science:

• Virology
• Cell Biology

Background:

• Persistent hepatitis A virus (HAV) infections involve the continuous production of viral particles within host cells.
• Understanding the composition and characteristics of these particles is crucial for comprehending viral replication and pathogenesis.

Purpose of the Study:

• To investigate the range and properties of hepatitis A virus particles generated during persistent infections across different cell lines.
• To characterize the physical and structural attributes of infectious virions versus non-infectious particles.

Main Methods:

• Buoyant density centrifugation in cesium chloride (CsCl) gradients.
• Sedimentation analysis using sucrose density gradients.
• Analysis of viral antigen mass and particle composition.

Main Results:

• A uniform profile of HAV particles was observed in most cell lines, with the infectious virion comprising less than 50% of the total viral antigen.
• Non-infectious, empty HAV particles were a major component, exhibiting distinct buoyant densities (1.305 g/ml and 1.20 g/ml CsCl) and sedimentation coefficients (76S and 59S).
• These empty particles demonstrated physical stability and capsid protein composition (VP0, VP1, VP3) similar to poliovirus.

Conclusions:

• Persistent HAV infections predominantly yield non-infectious empty particles alongside infectious virions.
• The characterization of these empty particles provides insights into HAV assembly and stability.
• HAV empty particles share similarities with other picornaviruses, suggesting conserved structural properties.