Trichovirus (taxid:40276)

VIRION

Non-enveloped, flexuous, filamentous,640-760 nm long and 10-12 nm in diameter.

GENOME

Linear ssRNA(+) genome of 7.5-8.0 kb in size. The 3' terminus is polyadenylated. Encodes for 3 proteins.

GENE EXPRESSION

The virion RNA is infectious and serves as both the genome and viral messenger RNA. RNA-dependent RNA polymerase (RdRp) is translated directly from the genomic RNA. ORF2 protein is translated by subgenomic RNA.

ENZYMES

• RNA-dependent RNA polymerase [Polyprotein]
• Alpha-type capping [Polyprotein]
• Polyprotein major protease (Peptidase C23) [Polyprotein]
• Fe2OG dioxygenase [Polyprotein]

REPLICATION

CYTOPLASMIC

1. Virus penetrates into the host cell.
2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
3. The viral RNA is translated as a monocistronic mRNA to produce the RdRp (encoded by the 5'-proximal ORF).
4. Replication occurs in viral factories. A dsRNA genome is synthesized from the genomic ssRNA(+).
5. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
6. Internal subgenomic promoters are used to transcribe the sgRNAs. Traduction of these sgRNAs yields the capsid and movement proteins.
7. Assembly of new virus particles.
8. Movement protein allows cell-to-cell movement.

Host-virus interaction

Suppression of RNA silencing

Apple chlorotic leaf spot virus 50 kDa movement protein acts as a systemic suppressor of RNA silencing through phloem .