Molecular biology
VIRION
Non-enveloped, with an icosahedral T=3 symmetry, about 35 nm in diameter. The capsid is composed of 180 capsid proteins. T=1 particles composed of 60 capsid proteins, about in diameter 15nm are also observed. Genomic or subgenomic RNA are encapsidated in different particles.
GENOME
Monopartite, linear, single-stranded, positive-sense RNA genome of 7.3 to 8.3 kb. At 5’-terminus a virus protein (VPg)is covalently linked to genome, whereas 3’-terminus is polyadenylated. th
GENE EXPRESSION
The virion RNA is infectious and serves as both genome and viral messenger RNA. ORF1 encodes a polyprotein cleaved into non-structural proteins and capsid protein. ORF2 encodes for a small structural protein (VP10) Cleavage of ORF1 polyprotein by the virus-encoded 3C-like cysteine proteinase yields the mature nonstructural proteins.
REPLICATION
- Virus attaches to host receptors and is internalized.
- Uncoating, and release of the viral genomic RNA into the cytoplasm.
- VPg is removed from the viral RNA, which is then translated into a processed ORF1 polyprotein to yield the mature non-structural proteins involved in RNA transcription.
- Negative-sense complementary ssRNAs are synthesized using the genomic RNAs as a templates.
- New genomic RNA is synthesized using the negative-sense RNA as a template, as well as subgenomic RNA encoding for ORF2 protein.
- Assembly and release of new virions.