Figure 1.

The genome architecture and the infection cycle of ssRNA phages. (A) The genome architecture of some culturable ssRNA phages. Their genomes contain three core genes: mat (encoding maturation protein), cp (encoding coat protein), and rep (encoding β-subunit of the replicase). (B) The infection cycle of ssRNA phages. The cycle starts with (1) the adsorption of ssRNA phage to the side of the retractile pilus; (2) the retraction of the pilus promotes the entry of gRNA into the host cell; (3) the genome is translated by host ribosomes to manufacture the viral structural proteins, as well as the replicase, which with host factors, synthesizes more of the viral genome; (4) the gRNA is encapsidated by CPs and interacts with the Mat to assemble into mature virions; and (5) the Lys encoded in the gRNA of ssRNA phages induces host lysis to release new viral progeny.