Arbitrium phages can manipulate each other’s lysis - lysogeny decisions

Summary Many viruses can switch between lytic replication and dormancy (or lysogeny). It was recently discovered that some viruses that infect bacteria (known as bacteriophage, or phage) employ peptide-based (“arbitrium”) communication systems to optimise their lysis/lysogeny switch: high peptide concentrations signal a lack of susceptible hosts and trigger lysogeny, while low peptide concentrations signal an abundance of uninfected hosts and prompt lysis. Here we demonstrate that Arbitrium-phages belonging to different species and genera can influence each others’ infection dynamics by secreting similar communication peptides, leading to early lysogenisation of the signal-receiving phage, and elevated fitness of the signal-emitting phage. Antagonistic coevolution between signal emitting and signal receiving phages to manipulate each other’s infection behaviours may explain the rapid diversification of arbitrium systems and their frequent horizontal exchange to escape the noise of cross talk.