Phasivirus

VIRION

Enveloped, spherical. Diameterabout 130nm.

GENOME

Segmented Negative-stranded RNA linear genome, L segment is about 6.8kb, M segment about 4.1kb and S segment about 1.3kb. Encodes for three proteins.

GENE EXPRESSION

Transcription is made in cytoplasm by viral RNA dependent RNA polymerase (L) binding to a promoter on each encapsidated segment.

REPLICATION

CYTOPLASMIC

  1. Virus attaches to host receptors though Gn-Gc glycoprotein dimer, 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.