Fig 1. Phage lytic infection cycle.

The phage infection cycle. This flows counterclockwise in the figure, starting from the upper left. (1) Phage attachment to receptor molecules found on bacteria [29,30] is typically described as processes of virion adsorption [31,32] with uptake involving movement of the virion genome from the phage virion into the bacterial cytoplasm. This can lead to the noted lysogenic cycles (main text) or, in some cases instead, pseudolysogeny [33–35], but as shown, particularly for virulent phages, gives rise to lytic cycles. (2) Synthesis is of phage-specific macromolecules including RNA, DNA, and proteins. Assembly is the process of generation of new virions from those macromolecules as resulting, ultimately, in (3) maturation of virions into adsorption proficient entities. (4) The timing of liberation of virions generally is under phage genetic control [36], though for certain types of phages (not tailed and also not shown), this release occurs chronically rather than lytically [25].