VIRION
Enveloped, spherical. Diameter of about 150 nm.
GENOME
Negative-stranded RNA linear genome, about 17 kb in size. Encodes for nine proteins.
GENE EXPRESSION
The viral RNA dependent RNA polymerase binds the encapsidated genome at the leader region, then sequentially transcribes each genes by recognizing start and stop signals flanking viral genes. mRNAs are capped and polyadenylated by the L protein during synthesis. The V protein is produced through RNA editing and the C protein is produced by Leaky scanning of The P mRNA.
ENZYMES
- RNA-dependent RNA polymerase [L]
- Mononega-type capping
- RNA TPase, GTase, N7 Mtase, 2'O Mtase [L]
- Neuraminidase [HN]
REPLICATION
CYTOPLASMIC
- Attachment to host cell surface receptors through HN glycoprotein.
- Fusion with the plasma membrane; ribonucleocapsid is released in the cytoplasm.
- Sequential transcription, viral mRNAs are capped and polyadenylated in the cytoplasm.
- Replication presumably starts when enough nucleoprotein is present to encapsidate neo-synthetized antigenomes and genomes.
- The ribonucleocapsid binds to the matrix protein and buds via the host ESCRT complexes occurs at the plasma membrane.