Self-assembly of dengue virus empty capsid-like particles in solution

Area of Science:

• Virology
• Structural Biology
• Biochemistry

Background:

• Nucleocapsid (NC) assembly is critical for virus replication, genome protection, and transmission.
• Flaviviruses' envelope structure is known, but their NC organization remains uncharacterized.
• Understanding flavivirus NC assembly is essential for developing antiviral strategies.

Purpose of the Study:

• To investigate the self-assembly mechanism of flavivirus nucleocapsid proteins in solution.
• To characterize a novel dengue virus capsid protein (DENVC) mutant for studying NC assembly.
• To elucidate the thermodynamic principles governing empty capsid formation in flaviviruses.

Main Methods:

• Engineered a DENVC mutant (R85C) by replacing arginine 85 with cysteine in the α4-helix.
• Utilized biophysical techniques to analyze capsid-like particle (CLP) self-assembly in solution.
• Investigated the thermodynamics of capsid assembly and DENVC stability.

Main Results:

• The R85C DENVC mutant spontaneously self-assembles into CLPs without nucleic acids.
• DENVC stability is enhanced by restricting α4/α4' motion, promoting efficient assembly.
• This study achieved the first in-solution assembly of empty flavivirus capsids.

Conclusions:

• The R85C mutant provides a novel system for studying flavivirus NC assembly mechanisms.
• Restricted inter-protein motion is crucial for stabilizing and assembling flavivirus capsids.
• This research opens new avenues for understanding flavivirus structural biology and developing antivirals.