Crystal structure of a nematode-infecting virus

Area of Science:

• Virology
• Structural Biology
• Nematology

Background:

• Orsay virus is the first identified virus naturally infecting Caenorhabditis elegans (a nematode).
• It possesses a bipartite, positive-sense RNA genome and shows relations to nodaviruses.
• Unique molecular features include a capsid-delta fusion protein and ATG-independent translation initiation.

Purpose of the Study:

• To determine the crystal structure of an Orsay virus-like particle.
• To understand the structural basis of Orsay virus unique features.
• To provide a structural framework for studying Orsay virus replication and pathogenesis.

Main Methods:

• Recombinant expression of Orsay virus capsid protein (CP).
• Assembly of virus-like particles.
• X-ray crystallography to determine the 3D structure.
• Structural comparisons with related viruses.

Main Results:

• The Orsay capsid exhibits T = 3 icosahedral symmetry with 60 trimeric surface spikes.
• Each CP consists of an N-terminal arm, an S domain (beta-barrel fold), and a P domain (surface spikes).
• The S domain aligns with plant RNA viruses, while the P domain shows distant relation to caliciviruses, suggesting evolutionary links. N-terminal arm removal impacts capsid stability and genome packaging.

Conclusions:

• The determined structure reveals unique features of the Orsay virus capsid.
• Structural insights suggest evolutionary relationships with plant viruses and potentially other virus families.
• The N-terminal arm is crucial for capsid stability and genome packaging.
• This structural information serves as a foundation for future research on Orsay virus infection mechanisms.