Emesvirus (taxid:2842664)

VIRION

Non-enveloped, spherical virion about 26 nm in diameter with T=3 icosahedral symmetry composed of 178 CP proteins and a single A maturation protein .
PBDe

GENOME

Monopartite, linear, ssRNA(+) genome about 3.5 kb in size. The 5' end is a triphosphate. Encodes 4 proteins.

GENE EXPRESSION

The virion RNA is infectious and serves as both the genome and viral messenger RNA. Encodes for 4 ORFs. Cp protein repress replicase translation by binding a RNA hairpin at the start site of this gene.

ENZYMES

• RNA-directed RNA polymerase

REPLICATION

1. Adsorption to F pili of target cells induces cleavage and release of A maturation protein.
2. Genomic RNA enters the bacterium.
3. Viral proteins are translated.
4. Viral replicase assembles with host proteins (ribosomal protein S1, translation elongation factors EF-Tu and EF-Ts) to form the active RNA polymerase.
5. Replication of genomic RNA into a minus strand, which serves as template to produce new positive strand genomes.
6. Late in infection CP protein bind to a RNA hairpin on the genome, and new virus particles are assembled in the cytoplasm.
7. Release by cell lysis.