Molecular biology
VIRION
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.
GENE EXPRESSION
The virion RNA is infectious and serves as both the genome and viral messenger RNA. The genome encodes a polyprotein (ORF1). One or two smaller ORFs are expressed from a subgenomic RNA. Cleavage of ORF1 polyprotein by the virus-encoded 3C-like cysteine proteinase yields the mature nonstructural proteins. The 3’-end terminal ORF encodes a basic protein (and the capsid protein). Vesiviruses are apparently unique among the caliciviruses in that the ORF2 encodes a capsid precursor protein that is proteolytically processed by the viral proteinase to yield the mature capsid protein.
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 RNAs are synthesized using the negative-sense RNAs as templates.
- Expression of sgRNA yields the basic protein (and capsid protein).
- Assembly and release of new virions.