VIRION
Enveloped, spherical. Diameter from 60 to 300 nm.
GENOME
Segmented Negative-stranded RNA linear genome, L segment is about 6.4 kb, M segment about 2-3 kb and S segment 2 kb.
Encodes for four proteins.
GENE EXPRESSION
M segment is ambisens. The viral RNA dependent RNA polymerase (L) binds to a promoter on each encapsidated segment, and transcribes a messenger RNA. Transcription is terminated by a strong hairpin sequence at the end of each gene. mRNAs are capped, probably by L protein during synthesis.
ENZYMES
REPLICATION
CYTOPLASM
- Virus attaches to host receptors though GP glycoprotein and is endocytosed into vesicles
- Fusion of virus membrane with the vesicle membrane; ribonucleocapsid is released in the cytoplasm.
- Sequential transcription, viral mRNAs are capped in the cytoplasm.
- Replication presumably starts when enough nucleoprotein is present to encapsidate neo-synthetized antigenomes and genomes.
- The ribonucleocapsid interacts with the Z protein under the plasma membrane and buds, releasing the virion.