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Updated: Jun 13, 2025

Author Spotlight: Investigating Bacteriophage-Induced Immune Responses in Gnotobiotic Mice
Published on: January 26, 2024
Multi-strain phage induced clearance of bacterial infections
Jacopo Marchi1, Chau Nguyen Ngoc Minh2, Laurent Debarbieux3
1Department of Biology, University of Maryland, College Park, MD, USA.
Abstract:
Bacteriophage (or 'phage' - viruses that infect and kill bacteria) are increasingly considered as a therapeutic alternative to treat antibiotic-resistant bacterial infections. However, bacteria can evolve resistance to phage, presenting a significant challenge to the near- and long-term success of phage therapeutics. Application of mixtures of multiple phage (i.e., 'cocktails') have been proposed to limit the emergence of phage-resistant bacterial mutants that could lead to therapeutic failure. Here, we combine theory and computational models of in vivo phage therapy to study the efficacy of a phage cocktail, composed of two complementary phages motivated by the example of Pseudomonas aeruginosa facing two phages that exploit different surface receptors, LUZ19v and PAK_P1. As confirmed in a Luria-Delbrück fluctuation test, this motivating example serves as a model for instances where bacteria are extremely unlikely to develop simultaneous resistance mutations against both phages. We then quantify therapeutic outcomes given single- or double-phage treatment models, as a function of phage traits and host immune strength. Building upon prior work showing monophage therapy efficacy in immunocompetent hosts, here we show that phage cocktails comprised of phage targeting independent bacterial receptors can improve treatment outcome in immunocompromised hosts and reduce the chance that pathogens simultaneously evolve resistance against phage combinations. The finding of phage cocktail efficacy is qualitatively robust to differences in virus-bacteria interactions and host immune dynamics. Altogether, the combined use of theory and computational analysis highlights the influence of viral life history traits and receptor complementarity when designing and deploying phage cocktails in immunocompetent and immunocompromised hosts.
Insights
Phage therapy uses viruses to kill bacteria. Using phage cocktails, especially in immunocompromised patients, can improve treatment outcomes and prevent bacteria from developing resistance to multiple phages simultaneously.
Area of Science:
- Microbiology
- Virology
- Computational Biology
Background:
- Antibiotic resistance is a growing threat, driving interest in phage therapy as an alternative treatment.
- Bacteria can evolve resistance to bacteriophages (phages), challenging the long-term efficacy of phage therapeutics.
- Phage cocktails, mixtures of multiple phages, are proposed to mitigate the emergence of phage-resistant bacterial mutants.
Purpose of the Study:
- To investigate the efficacy of phage cocktails against bacterial infections using theoretical and computational models.
- To analyze how phage cocktails perform compared to single-phage treatments, considering factors like bacterial resistance and host immunity.
- To explore the impact of phage traits and receptor complementarity on therapeutic outcomes in both immunocompetent and immunocompromised hosts.
Main Methods:
- Development and application of computational models simulating in vivo phage therapy.
- Utilizing a two-phage cocktail model inspired by Pseudomonas aeruginosa and phages LUZ19v and PAK_P1, which target different surface receptors.
- Performing Luria-Delbrück fluctuation tests to confirm the low probability of simultaneous resistance evolution.
Main Results:
- Phage cocktails targeting independent bacterial receptors enhance treatment outcomes, particularly in immunocompromised hosts.
- Cocktails significantly reduce the likelihood of bacteria evolving simultaneous resistance to multiple phages.
- Therapeutic efficacy is robust across variations in phage-bacteria interactions and host immune responses.
Conclusions:
- Phage cocktails offer a promising strategy to overcome bacterial resistance in phage therapy.
- The design of effective phage cocktails should consider viral life history traits and receptor complementarity.
- Computational modeling is a valuable tool for optimizing phage cocktail deployment in clinical settings.
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