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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Engineered phages evade the complete defense repertoire of highly phage-resistant MRSA clinical isolates
Sarah M Voss1, Katharine C King1, Devin J Hunt1
1Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Abstract:
Phage therapy is a re-emerging approach for antimicrobial-resistant bacterial infections. However, the narrow host range of most phages remains a major barrier to the success and wider adoption of phage therapy. Although receptor incompatibility is often assumed to define phage-host specificity, we demonstrate that anti-phage defense systems are major determinants of host range in Staphylococcus aureus. Using a methicillin-resistant S. aureus (MRSA) clinical isolate as a model, we characterized the targeting profiles of its 15 defense systems and, for the first time, generated therapeutic phages that evade the full defense repertoire of a multi-phage-resistant strain. In particular, we show that defense-guided phage recombination is a powerful tool that leverages the modular design of phage genomes to replace targeted with untargeted components. Our holistic approach unveils defense synergies that constrain phage evasion and redundancies that allow the simultaneous evasion of multiple defenses. Finally, we show that an engineered phage cocktail prevents the emergence of phage resistance in the model and a second clinical strain with similar defenses. Our work provides a blueprint for translating our expanding knowledge of defense system identity and mechanism into the rational design of effective, next-generation phage therapeutics.
Insights
Phage therapy faces challenges due to limited host range. This study reveals that bacterial defense systems, not just receptor incompatibility, dictate phage effectiveness, offering a new strategy for developing broad-acting phage therapeutics.
Area of Science:
- Microbiology
- Genetics
- Immunology
Background:
- Phage therapy is a promising alternative for treating infections caused by antibiotic-resistant bacteria.
- The narrow host range of bacteriophages (phages) limits their therapeutic application.
- Bacterial anti-phage defense systems are increasingly recognized as critical factors in phage-host interactions.
Purpose of the Study:
- To investigate the role of anti-phage defense systems in determining the host range of phages targeting *Staphylococcus aureus*.
- To engineer therapeutic phages capable of evading comprehensive defense mechanisms in multi-drug resistant strains.
- To develop strategies for overcoming phage resistance in bacterial pathogens.
Main Methods:
- Characterization of 15 defense systems in a methicillin-resistant *S. aureus* (MRSA) clinical isolate.
- Generation of therapeutic phages engineered to evade identified defense systems.
- Utilizing defense-guided phage recombination to replace targeted phage components.
- Construction and testing of phage cocktails against MRSA and a second clinical isolate.
Main Results:
- Bacterial defense systems, rather than receptor incompatibility, are major determinants of phage host range in *S. aureus*.
- Successfully generated phages that evade the complete defense repertoire of a multi-defense *S. aureus* strain.
- Identified defense synergies that hinder phage evasion and redundancies that permit simultaneous evasion of multiple defenses.
- An engineered phage cocktail prevented the emergence of phage resistance in two clinical *S. aureus* strains.
Conclusions:
- Bacterial defense systems play a crucial role in limiting phage efficacy and represent key targets for engineering broader-spectrum phage therapeutics.
- Defense-guided phage recombination is an effective strategy for overcoming bacterial defenses and designing next-generation phage therapies.
- A rational, defense-informed approach to phage cocktail design can prevent the emergence of phage resistance, enhancing therapeutic outcomes.
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