Do plasmid-dependent phages enable the survival of costly plasmids?

Plasmid-dependent phages can enable high-cost plasmid survival by keeping the plasmid at low abundance, neutralizing population-level costs and extending persistence time.

• Why it matters: Plasmid loss can be favored when benefits are temporary but costs persist, yet loss can also drive plasmid extinction, permanently removing plasmid-derived advantages. This work tests a worst-case setting where benefits are infrequent, costs are heavy and unrelieved, and a competitor cannot acquire the plasmid.
• What they did: Using population models of hosts carrying a costly plasmid, the study adds plasmid-dependent phage predation that preferentially targets low-abundance plasmid carriers. It then tracks plasmid persistence and spread when plasmid benefits switch from absent to present.
• The result: Phage predation pins plasmid abundance low, effectively neutralizing plasmid cost at the population level and boosting persistence time. When benefits become available, the plasmid spreads and survives via vertical transmission until benefits subside.

AI summary of the abstract · may contain errors · not medical advice · read the paper.