Beet yellows virus: the importance of being different

Area of Science:

• Virology
• Plant Pathology
• Molecular Biology

Background:

• Beet yellows virus (BYV) is the type member of the genus Closterovirus, family Closteroviridae.
• It belongs to the alphavirus-like supergroup of positive-strand RNA viruses.
• BYV primarily affects sugar beet and spinach, with a broad host range impacting approximately 120 species across 15 families.

Purpose of the Study:

• To describe the taxonomic relationship, physical properties, and protein composition of Beet yellows virus (BYV).
• To identify the primary hosts and suitable propagation species for BYV.

Main Methods:

• Taxonomic classification based on established viral families and supergroups.
• Description of virion structure, including dimensions, RNA content, and protein components.
• Identification of viral genes (ORFs) and their encoded proteins, including structural and functional roles.

Main Results:

• BYV virions are flexuous filaments (approx. 1300 nm x 12 nm) containing ~15.5 kb RNA and five proteins.
• The major capsid protein constitutes ~95% of the virion length, with other proteins forming the tail.
• Viral proteins include RNA replicase, membrane proteins, and structural components, encoded by ORFs 1a-8.

Conclusions:

• BYV possesses a complex structure with distinct protein components essential for its virion assembly.
• Understanding BYV's biology is crucial for managing its impact on economically important crops like sugar beet and spinach.
• The virus's broad host range necessitates careful monitoring in agricultural settings.