Molecular biology
VIRION
Non-enveloped, flexuous, filamentous, of 720-850 nm long and 12-15 nm in diameter. Symmetry helical. Presence of characteristic inclusion bodies within infected plant cells.
GENOME
Monopartite, linear, ssRNA(+) genome of 10 kb in size. 3’ terminus has a poly (A) tract. 5’ terminus has a genome-linked protein (VPg).
GENE EXPRESSION
The virion RNA is infectious and serves as both the genome and viral messenger RNA. The genomic RNA is translated into polyproteins which are subsequently processed by the action of three viral-encoded proteinases into functional products.
REPLICATION
CYTOPLASMIC
- Virus penetrates into the host cell.
- Uncoating, and release of the viral genomic RNA into the cytoplasm.
- The viral RNA is translated to produce a polyprotein which is processed by viral proteases.
- A negative-sense complementary ssRNA is synthesized using the genomic RNA as a template.
- New genomic RNA is synthesized using the negative-sense RNA as a template.
- Formation of new virus particles.