A pocket-factor-triggered conformational switch in the hepatitis B virus capsid

Area of Science:

• Virology
• Structural Biology
• Biochemistry

Background:

• Viral hepatitis, particularly hepatitis B virus (HBV), presents a significant global health challenge.
• Understanding HBV virion morphogenesis is crucial for developing effective antiviral therapies.
• Previous observations suggested a conformational switch in HBV capsids regulates envelopment.

Purpose of the Study:

• To identify the structural basis of regulated capsid envelopment in HBV.
• To investigate the role of capsid conformation in HBV maturation and secretion.
• To propose a mechanism for therapeutic intervention targeting HBV envelopment.

Main Methods:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy was employed to determine capsid structure.
• Analysis focused on the hydrophobic pocket of the HBV core protein and its interactions.
• Investigated the effect of pocket factor binding on capsid conformation.

Main Results:

• A stable alternative conformation of the HBV capsid was identified.
• Structural changes are concentrated in the hydrophobic pocket of the core protein.
• Specific, high-affinity binding of a pocket factor triggers this conformational switch.
• The induced conformational change acts as a maturation signal for envelopment.

Conclusions:

• The "synergistic double interaction" hypothesis explains the regulation of HBV capsid envelopment.
• Identified a potential target for therapeutic strategies aimed at inhibiting HBV envelopment.
• The findings provide insights into the intricate mechanisms of viral maturation.