Question

Which virus has emerged as a model system to study capsid assembly?

• A. Hepatitis B virus
• B. Pox virus
• C. Rabies virus
• D. Picorna virus

Hint:

The HBV core protein spontaneously self-assembles in vitro into 120-dimer icosahedral capsids.
This provides a highly predictable and clean system to study macromolecular thermodynamics.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Viral capsids are highly symmetrical macromolecular protein shells that package the viral genome.
Studying how these capsids assemble is crucial for understanding viral lifecycles and developing antiviral therapeutics.

Step 2: Detailed Explanation:
The Hepatitis B Virus (HBV) (A) has emerged as an exceptionally valuable model system to study capsid assembly.
The HBV core protein (Cp) is a relatively small homodimeric protein that can self-assemble in vitro in the absence of nucleic acids or other cellular scaffolding proteins.
Under appropriate ionic strength and temperature, purified Cp dimers spontaneously assemble into stable, spherical icosahedral capsids (\(T=4\) or \(T=3\) symmetry).
This robustness makes HBV the premier model system for biophysical, thermodynamic, and structural studies of self-assembly.
These studies have helped researchers model protein-protein interactions and design assembly-directed antivirals.
Other viruses like Poxvirus are too complex, while Rabies virus has an asymmetrical bullet-shaped helical nucleocapsid, making them less suitable as simple self-assembly models.

Step 3: Final Answer:
Hepatitis B virus has emerged as a model system to study capsid assembly.