Actinovirus

VIRION

Enveloped, spherical. Diameter possibly from 80 to 120nm.

GENOME

Segmented Negative-stranded RNA linear genome, L segment is about 6.5 kb, M segment about 3.9 kb and S segment about 1.4 kb.
Encodes for at least three proteins.

GENE EXPRESSION

The viral RNA dependent RNA polymerase (L) binds to a promoter on each encapsidated segment, and transcribes the mRNA. These are capped by L protein during synthesis using cap snatching . Transcription is terminated by a strong hairpin sequence at the end of each gene. mRNAs are capped by L protein during synthesis.

REPLICATION

CYTOPLASMIC

  1. Virus attaches to host receptors though glycoprotein, and is endocytosed into vesicles in the host cell.
  2. Fusion of virus membrane with the vesicle membrane; ribonucleocapsid segments are released in the cytoplasm.
  3. Transcription, viral mRNAs are capped in the cytoplasm.
  4. Replication presumably starts when enough nucleoprotein is present to encapsidate neo-synthetized antigenomes and genomes.
  5. The ribonucleocapsids buds at Golgi apparatus, releasing the virion by exocytosis.