Citrivirus

VIRION

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Non-enveloped, flexuous, filamentous, about 960 nm long and 12 nm in diameter.

GENOME

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Linear ssRNA(+) genome of 8.7 kb in size. The 5' end is capped and 3' terminus is polyadenylated. Encodes 3 ORFs.

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 putative movement protein (ORF2) and capsid (ORF3) proteins are transcribed from 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.
  8. Movement protein allows cell-to-cell movement.

Host-virus interaction

Suppression of RNA silencing

Citrus leaf blotch virus movement protein acts as suppressor of RNA silencing .