Non-enveloped, flexuous, filamentous, of one (690-720nm) or two (500-600 and 200-300 nm) lengths x 11-15 nm in diameter. Symmetry helical. Presence of characteristic inclusion bodies within infected plant cells.
Monopartite or bipartite, linear, ssRNA(+) genome of 9-10 kb in size. 3’ terminus has a poly (A) tract. 5’ terminus has a genome-linked protein (VPg).
The virion RNA is infectious and serves as both the genome and viral messenger RNA. The genomic RNA (or genome segments) is translated into polyprotein(s) which is subsequently processed by virus-encoded proteases into functional products. P3N-PIPO is expressed by polymerase slippage mechanism from the P3 ORF and probably acts as a movement protein.
Cleavage sites in the family Potyviridae
- 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 into the RdRp protein and structural proteins.
- Replication takes place in cytoplasmic viral factories. A dsRNA genome is synthesized from the genomic ssRNA(+).
- The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
- Virus assembly in the cytoplasm.
- Viral movement protein P3N-PIPO probably mediates virion cell-to-cell transfer.