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In this manuscript, we isolate and characterize a phage that displays what we call anti-bacterial hyper-aggressive behavior. This behavior appears ideal for phage therapy of bacterial disease. It includes (1) formation of semi-turbid zones that subsequently clear, (2) formation of miniature satellite plaques, which probably constitute the foundation of the semi-turbid zones, (3) multi-day enlargement of both circular plaques and cleared semi-turbid zones, and (4) non-formation of phage-resistant host colonies. We emphasize the following key details in our response. (1) The semi-turbid zones are asymmetric and occupy an area much larger (2–10x) than the area of circular plaques formed on the same Petri plate (unlike semi-turbid plaques associated with other phenomena, such as lysis inhibition and lysogeny). (2) In the manuscript’s Figure 9d, we note that phage 0524phi7-1 destroys mature colonies of the host (unlike the behavior of other aggressive phages). (3) The asymmetry of semi-turbid zones is a point that we should have emphasized (because it implies non-diffusive, energy-requiring phage transport). (4) The input of energy for phage motion can be physical (to which we add some details for two physical effects); our mentioning of phage swimming is a hypothesis (that is, however, still viable).
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This content will become publicly available on April 1, 2026
Bypassing Evolution of Bacterial Resistance to Phages: The Example of Hyper-Aggressive Phage 0524phi7-1
The ideal bacteriophages (phages) for the treatment of bacterial disease (phage therapy) would bypass bacterial evolution to phage resistance. However, this feature (called a hyper-aggression feature) has never been observed to our knowledge. Here, we microbiologically characterize, fractionate, genomically classify, and perform electron microscopy of the newly isolated Bacillus thuringiensis phage 0524phi7-1, which we find to have this hyper-aggression feature. Even visible bacterial colonies are cleared. Phage 0524phi7-1 also has three other features classified under hyper-aggression (four-feature-hyper-aggressive phage). (1) Phage 0524phi7-1 forms plaques that, although sometimes beginning as semi-turbid, eventually clear. (2) Clear plaques continue to enlarge for days. No phage-resistant bacteria are detected in cleared zones. (3) Plaques sometimes have smaller satellite plaques, even in gels so concentrated that the implied satellite-generating phage motion is not bacterial host generated. In addition, electron microscopy reveals that phage 0524phi7-1 (1) is a myophage with an isometric, 91 nm-head (diameter) and 210 nm-long contractile tail, and (2) undergoes extensive aggregation, which inhibits typical studies of phage physiology. The genome is linear double-stranded DNA, which, by sequencing, is 157.103 Kb long: family, Herelleviridae; genus, tsarbombavirus. The data suggest the hypothesis that phage 0524phi7-1 undergoes both swimming and hibernation. Techniques are implied for isolating better phages for phage therapy.
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- Award ID(s):
- 2409676
- PAR ID:
- 10653918
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- International Journal of Molecular Sciences
- Volume:
- 26
- Issue:
- 7
- ISSN:
- 1422-0067
- Page Range / eLocation ID:
- 2914
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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