Inherent symmetry and flexibility in hepatitis B virus subviral particles

Area of Science:

• Virology
• Structural Biology
• Hepatology

Background:

• Chronic hepatitis B virus (HBV) infection is a significant global health issue with high morbidity and mortality.
• Current treatments for HBV infection offer limited virus clearance, often requiring lifelong management.
• The structure and assembly of HBV surface antigen (HBsAg) on the viral envelope are not well understood, hindering therapeutic development.

Purpose of the Study:

• To determine the high-resolution structure of HBsAg.
• To elucidate the assembly mechanisms of HBsAg into subviral particles and virions.
• To provide structural insights into HBsAg's role in HBV infection and potential therapeutic targets.

Main Methods:

• Cryo-electron microscopy (cryo-EM) analysis of HBsAg.
• Processing of extensive datasets to achieve near-atomic resolution.
• Computational modeling to understand HBsAg assembly and interactions.

Main Results:

• Near-atomic resolution (3.7 angstroms) structure of HBsAg was determined.
• HBsAg homodimers were observed to assemble into subviral particles with 2- and 4-like quasisymmetry.
• Structural insights into dense-packing rules, adaptability, and higher-order filament formation of HBsAg were gained.

Conclusions:

• The study provides unprecedented structural detail of HBsAg, a key diagnostic and prognostic marker for HBV.
• Understanding HBsAg assembly mechanisms offers potential targets for novel antiviral strategies against chronic hepatitis B.
• These findings advance our knowledge of HBV virion formation and HBsAg-capsid interactions.