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Published on: October 1, 2007
Therapeutic Application of Bacteriophage PHB02 and Its Putative Depolymerase Against Pasteurella multocida Capsular
Yibao Chen1,2,3, Erchao Sun1,2,3, Lan Yang1,2,3
1State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.
Abstract:
Phage PHB02 specifically infects Pasteurella multocida capsular serogroup A strains. In this study, we found that capsule deletion mutants were not lysed by PHB02, suggesting that the capsule of P. multocida serogroup A strains might be the primary receptor. Based on sequence analysis, a gene encoding a phage-associated putative depolymerase was identified. The corresponding recombinant depolymerase demonstrated specific activity against capsular serogroup A strains but did not strip capsule deletion mutants. In vivo experiments showed that PHB02 was retained at detectable levels in the liver, spleen, kidneys, lung, and blood, at 24 h post-administration in mice. Depolymerase plus serum significantly reduced the number of viable wild-type P. multocida strain HB03 cells (3.5-4.5 log decrease in colony-forming units). Moreover, treatment with phage or purified depolymerase resulted in significantly increased survival of mice infected with P. multocida HB03, and an absence of increase of eosinophils and basophils or other pathological changes when compared with the control group. These results show that phage PHB02 and its putative depolymerase represent a novel strategy for controlling P. multocida serogroup A strains.
Insights
Phage PHB02 targets Pasteurella multocida serogroup A by recognizing its capsule. Its depolymerase enzyme offers a promising new approach for controlling this bacterium, enhancing mouse survival in studies.
Area of Science:
- Microbiology
- Bacteriology
- Virology
- Animal Health
Background:
- Pasteurella multocida is a significant bacterial pathogen affecting various animal species.
- Serogroup A strains of P. multocida possess a capsule crucial for virulence.
- Bacteriophages are viruses that infect bacteria and are being explored as therapeutic agents.
Purpose of the Study:
- To investigate the host range and receptor of phage PHB02 against Pasteurella multocida.
- To characterize the function of a putative depolymerase enzyme encoded by phage PHB02.
- To evaluate the therapeutic potential of phage PHB02 and its depolymerase against P. multocida infections in vivo.
Main Methods:
- Phage infection assays with wild-type and capsule deletion mutants of P. multocida.
- Sequence analysis to identify phage-associated genes, including a putative depolymerase.
- Recombinant depolymerase activity assays and in vivo efficacy studies in a mouse infection model.
Main Results:
- Phage PHB02 specifically infects P. multocida capsular serogroup A strains, with the capsule identified as the likely receptor.
- A phage-encoded depolymerase was identified and shown to specifically degrade the serogroup A capsule.
- Treatment with phage PHB02 or its depolymerase significantly reduced bacterial load and increased survival rates in infected mice, with no observed adverse pathological effects.
Conclusions:
- Phage PHB02 utilizes the P. multocida serogroup A capsule as its primary receptor.
- The phage-associated depolymerase is a key factor in phage infection and can be used therapeutically.
- Phage PHB02 and its depolymerase represent a novel and effective strategy for controlling P. multocida serogroup A infections.
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