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 genome and viral messenger RNA. ORF1 encodes for the non-structural polyprotein. Subgenomic RNA encodes for VP1 capsid protein and VP2 minor structural protein which is translated by ribosomal reinitiation. Cleavage of ORF1 polyprotein by the virus-encoded 3C-like cysteine proteinase yields the mature nonstructural proteins.

REPLICATION

CYTOPLASMIC

1. Virus attaches to host receptors and is internalized.
2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
3. 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.
4. Negative-sense complementary ssRNAs are synthesized using the genomic RNAs as a templates.
5. New genomic RNA is synthesized using the negative-sense RNA as a template, as well as subgenomic RNA encoding for structural proteins.
6. Assembly of new virions and release by cell lysis.