(formerly named Leviviridae)
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 .
Monopartite, linear, ssRNA(+) genome about 3.4-4.3 kb in size. The 5' end is a triphosphate. Encodes 3 (Allelovirus) or 4 proteins (Levivirus).
The virion RNA is infectious and serves as both the genome and viral messenger RNA. Encodes 4 ORFs. Cp protein represses replicase translation by binding a RNA hairpin at the start site of this gene.
Lysis protein is expressed by suppression of termination of an UGA nonsense codon in Allolevivirus genus.
- Adsorption to F pili of target cells induces cleavage and release of the maturation protein.
- Genomic RNA enters the bacterium.
- Viral proteins are translated.
- Viral replicase assembles with host proteins (ribosomal protein S1, translation elongation factors EF-Tu and EF-Ts) to form the active RNA polymerase.
- Replication of genomic RNA into a minus strand, which serves as template to produce new positive strand genomes.
- Late in infection CP protein bind to a RNA hairpin on the genome, and new virus particles are assembled in the cytoplasm.
- Release by cell lysis.