Molecular biology

VIRION

Non-enveloped, bacilliform with a T=1 icosahedral symmetry, about 50 nm length and 20 nm large.

GENOME

Linear, ssRNA(+) genome of 4 kb. The genome contains four major and three minor ORFs.

GENE EXPRESSION

Genomic RNA serves as both the genome and viral messenger RNA. ORF2 is a polyprotein which is possibly auto-cleaved by the ORF2 viral protease. ORF3 encodes the RNA dependent RNA polymerase and may betranslatted by frameshift as an ORF2-ORF3 polyprotein. The single capsid protein is translated from a subgenomic RNA (ORF4).

REPLICATION

CYTOPLASMIC

1. Virus penetrates into the host cell.
2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
3. Genomic RNA is translated to produce replication proteins.
4. An antigenomic complementary ssRNA is synthesized using the genomic RNA as a template.
5. Using antigenomic RNA as a template, new genomic RNAs are synthesized as well as subgenomic RNAs encoding for capsid protein.
6. Assembly of new virus particles.