Enveloped, spherical, 70-80nm in diameter. The capsid is not icosahedric and bound to the membrane . Envelope glycoproteins are assembled in helical organization .
Vidya Mangala Prasad, Thomas Klose, Michael G. Rossmann
PLoS Pathog. June 2017; 13: e1006377
Vidya Mangala Prasad, Steven D. Willows, Andrei Fokine, Anthony J. Battisti, Siyang Sun, Pavel Plevka, Tom C. Hobman, Michael G. Rossmann
Proc. Natl. Acad. Sci. U.S.A. 10 December 2013; 110: 20105?20110
Monopartite, linear, ssRNA(+) genome of 9.7 kb. The genome is capped and polyadenylated.
The virion RNA is infectious and serves as both genome and viral messenger RNA. The whole genome is translated in a non-structural polyprotein which is processed by host and viral proteases. Structural polyprotein is expressed through a subgenomic mRNA.
- Attachement of the viral E glycoprotein to host receptors mediates clathrin-mediated endocytosis of virus into the host cell.
- Fusion of virus membrane with host endosomal membrane. RNA genome is released into the cytoplasm.
- The positive-sense genomic ssRNA is translated into a polyprotein, which is cleaved into non-structural proteins necessary for RNA synthesis (replication and transcription).
- Replication takes place in cytoplasmic viral factories at the surface of endosomes. A dsRNA genome is synthesized from the genomic ssRNA(+).
- The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
- Expression of the subgenomic RNA (sgRNA) gives rise to the structural proteins.
- Capsid assembly occurs at the Golgi membrane.
- The capsid is envelopped by budding at Golgi membrane where the virion exits the cell.