Coinfecting phages impede each other's entry into the cell

Area of Science:

• Microbiology
• Virology
• Molecular Biology

Background:

• Temperate phages decide between lysis and lysogeny based on environmental virus-host ratios.
• Phage lambda's lysogeny propensity increases with coinfecting viruses, suggesting it infers population ratios.
• This inference relies on accurate mapping between extracellular ratios and intracellular multiplicity of infection (MOI).

Purpose of the Study:

• To investigate the accuracy of the mapping between extracellular phage-to-bacteria ratios and intracellular MOI.
• To understand how phage entry dynamics influence the developmental choice of temperate phages.
• To elucidate the role of phage entry in determining infection outcomes.

Main Methods:

• Simultaneous labeling of phage capsids and genomes to track entry.
• Single-cell infection experiments using a microfluidic device.
• Stochastic modeling to interpret phage entry dynamics.
• Assessing host physiological changes like membrane integrity and potential.

Main Results:

• Extracellular phage-to-bacteria ratios are sampled reliably by phage attachment, but not by entry.
• Phage entry probability and rate decrease with increasing numbers of adsorbed phages.
• Phage attachment perturbs host physiology, compromising membrane integrity and potential.
• Protracted entry of coinfecting phages increases heterogeneity in infection outcomes.

Conclusions:

• The premise of accurate mapping between extracellular ratios and intracellular MOI is faulty.
• Phage entry dynamics, influenced by MOI-dependent host perturbation, significantly impact infection outcomes.
• Entry dynamics play a crucial, previously unappreciated role in bacteriophage infection outcomes.
• Findings apply to multiple phages, including lambda, T5, and P1.