Communication between viruses guides lysis–lysogeny decisions

Abstract

Temperate viruses can become dormant in their host cells, a process called lysogeny. In every infection, such viruses need to decide between the lytic and the lysogenic cycles, i.e., whether to replicate and lyse their host or to lysogenize and keep the host viable. Here we show that viruses (phages) of the spBeta group use a small-molecule communication system to coordinate lysis-lysogeny decisions. During infection of its Bacillus host cell, the phage produces a 6aa communication peptide that is released to the medium. In subsequent infections, progeny phages measure the concentration of this peptide and lysogenize if the concentration is sufficiently high. We found that different phages encode different versions of the communication peptide, demonstrating a phage-specific peptide communication code for lysogeny decisions. We termed this communication system the “arbitrium” system, and further show that it is encoded by 3 phage genes: aimP, producing the peptide, aimR, the intracellular peptide receptor, and aimX, a negative regulator of lysogeny. The arbitrium system enables an offspring phage to communicate with its predecessors, i.e., to estimate the amount of recent prior infections and hence decide whether to employ the lytic or lysogenic cycle.

Mixing alters the lytic activity of viruses in the dark ocean

“…2009, Erez et al. 2017). Increases in FIC relative to the controls coincided with increases in VP (Figs.…”

“…2009, Erez et al. 2017). Also, the level of lysogeny in viral communities at the surface may be influenced by environmental parameters such as temperature, trophic conditions, or drastic changes in salinity (e.g., Williamson and Paul 2004, 2006, Cissoko et al.…”

Ecological and Evolutionary Benefits of Temperate Phage: What Does or Doesn't Kill You Makes You Stronger

“…Key among these are the insertion/excision events. The benefits of lysogeny versus lysis are likely to depend on the prevailing environmental conditions, for example, prophage insertion is more likely when the multiplicity of infection is high [62] (when the availability of hosts is limited), whereas excision is induced by the bacterial SOS response [63] (when the probability of vertical transmission in that host is low).…”

Phage particles do not communicate with each other or make decisions to either lyse or lysogenize their host cells

“…In a recent paper published in Nature, the sensational claim was made that phage particles of the SPbeta group are able to communicate with each other by allegedly producing an hexapeptide that is released in the culture medium [3]. Progeny phages were said to be able to measure the concentration of this peptide and if the concentration was sufficiently high, the phages would decide to lysogenize their bacterial host cells instead of killing them by lysis.…”

“…The original aim of the Erez et al study [3] was to investigate whether Bacillus subtilis bacteria infected with the phi3T phage were able to secrete peptides that would alert other B subtilis cells to the impending likelihood of phage infection, which would allow these cells to choose the lysogenic option and avoid the deadly lytic cycle. When it was found that the infected bacteria did produce a signalling hexapeptide, the authors ascribed its synthesis to the infecting phage, assuming that viruses synthesize peptides in order to communicate with other virus particles !…”