Cryo-Electron Microscopy Structure of Seneca Valley Virus Procapsid

Area of Science:

• Structural virology
• Picornaviridae family
• Virus-based therapeutics

Background:

• Seneca Valley virus (SVV) forms naturally occurring empty capsids (procapsids) with potential for stable virus-like particles.
• SVV is a livestock pathogen with potential therapeutic applications, particularly in treating small-cell lung cancers due to preferential tumor cell infection.
• The function and formation of procapsids remain unclear, despite their occurrence in some viral infections.

Purpose of the Study:

• To investigate the structure of SVV procapsids using cryo-electron microscopy.
• To describe the transition of capsid protein VP0 to its cleaved forms, VP4 and VP2.
• To understand the role of RNA in procapsid stabilization and acid stability.

Main Methods:

• Cryo-electron microscopy was employed to determine the high-resolution structure of SVV procapsids.
• Structural comparison between procapsids and full SVV virions.
• Analysis of SVV receptor binding to procapsids to confirm native antigenicity.

Main Results:

• The SVV procapsid structure was elucidated, revealing the transition of VP0 to VP4 and VP2.
• Evidence of SVV receptor binding to the procapsid, confirming its native antigenicity.
• An internal RNA cage was identified, contributing to the stabilization and increased acid stability of the procapsid.

Conclusions:

• SVV procapsids possess native antigenicity and are stabilized by an internal RNA cage, enhancing their acid stability.
• Understanding procapsid formation and behavior can lead to the development of SVV-based vaccines for the agricultural industry.
• Modified procapsids hold promise for targeted in vivo delivery of therapeutics, particularly for cancer treatment.