Molecular biology

VIRION

Non-enveloped, icosahedral, 25-30 nm in diameter, with icosahedral pseudo T=3 symmetry.

GENOME

Bi-partite linear ssRNA(+) genome of 7 kb for RNA1 and 3.3 kb for RNA2. The 3’terminus is polyadenylated.

GENE EXPRESSION

The virion RNA are infectious and serves as both the genome and viral messenger RNA. Both RNA encode a single polyprotein thatis processed to yield the mature proteins.

REPLICATION

CYTOPLASMIC

1. Virus penetrates into the host cell.
2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
3. The viral RNA is translated to produce polyproteins which are processed by viral proteases.
4. Negative-sense complementary ssRNAs are synthesized using genomic RNAs as a template.
5. New genomic RNA are synthesized using the negative-sense RNAs as template.
6. Formation of new virus particles.