Botrexvirus

VIRION

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Non-enveloped, flexuous, filamentous virion, about 720 nm long and 12-13 nm in diameter.

GENOME

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Linear ssRNA(+) genome of about 7 kb in size. The 3' terminus is polyadenylated and the 5' end is capped. Encodes 5 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. The other ORFs are transcribed presumably as monocistronic subgenomic mRNAs (sgRNAs).

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.