Deltaflexivirus

VIRION

Not yet observed (Oct_2018). May be capsidless.

GENOME

Linear ssRNA(+) genome of 6 to8 kb in size. The 5' end may possibly be capped and 3' terminus is polyadenylated. Encodes for 4 to 5 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 by readthrough of a ‘leaky’ stop codon between the helicase and RdRp regions.

REPLICATION

CYTOPLASMIC

  1. Virus penetrates into the host cell.
  2. 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 promoter lean to to transcribe the sgRNA.