Structure of the mite-transmitted Blackcurrant reversion nepovirus using electron cryo-microscopy

Area of Science:

• Plant virology
• Structural biology
• Molecular biology

Background:

• Blackcurrant reversion virus (BRV) is a significant mite-transmitted pathogen affecting Ribes species, causing blackcurrant reversion disease.
• BRV possesses a single-stranded, bipartite RNA genome enclosed by a capsid protein (CP).

Purpose of the Study:

• To determine the three-dimensional structure of BRV using cryo-electron microscopy (cryoEM).
• To model the BRV capsid protein and understand its structural arrangement.
• To identify potential antigenic sites for diagnostic antibody development.

Main Methods:

• Cryo-electron microscopy (cryoEM) and image reconstruction were employed to determine the BRV structure at 1.7 nm resolution.
• Homology modeling was used to fit the BRV capsid protein structure into the cryoEM reconstruction, comparing it to tobacco ringspot virus (TRSV).
• Peptide antibodies were generated against predicted exposed C-terminal sequences of the BRV CP.

Main Results:

• The cryoEM reconstruction revealed a pseudo T=3 viral capsid structure for BRV, similar to TRSV.
• Homology modeling indicated that the BRV CP's C-terminus is surface-exposed, while the N-terminus is interior.
• Generated antibodies successfully reacted with the virus, confirming the exposed C-terminal epitopes.

Conclusions:

• The determined structure provides insights into the BRV capsid organization.
• Homology modeling is a viable approach for identifying epitopes for diagnostic antibody generation.
• This research supports the development of improved diagnostic testing for BRV in commercial crops.