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Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins
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Two T7-like Bacteriophages, K5-2 and K5-4, Each Encodes Two Capsule Depolymerases: Isolation and Functional
Pei-Fang Hsieh1, Hsiao-Hsuan Lin1,2, Tzu-Lung Lin1
1Department of Microbiology, National Taiwan University College of Medicine, Taipei, Taiwan.
Scientific Reports
|July 6, 2017
Summary
Two Klebsiella phages, K5-2 and K5-4, were identified with capsule depolymerase activity. These phages show potential for Klebsiella pneumoniae typing and infection treatment.
Area of Science:
- Microbiology
- Virology
- Biochemistry
Background:
- Klebsiella pneumoniae is an opportunistic pathogen often associated with hospital-acquired infections.
- Bacteriophages offer a promising alternative or adjunct to antibiotics for treating bacterial infections.
- Capsular polysaccharides (CPS) are key virulence factors in K. pneumoniae, influencing host-pathogen interactions.
Purpose of the Study:
- To isolate and characterize bacteriophages targeting specific Klebsiella capsular types.
- To investigate the enzymatic activity of phage-encoded proteins on Klebsiella CPS.
- To evaluate the therapeutic potential of these bacteriophages against K. pneumoniae infections.
Main Methods:
- Isolation and characterization of Klebsiella bacteriophages K5-2 and K5-4.
- Identification and analysis of open reading frames (ORFs) encoding putative capsule depolymerases.
- In vitro enzymatic assays using purified depolymerases and Klebsiella CPS.
- Assessment of phage infectivity on bacterial mutants lacking specific capsule types.
- In vivo efficacy studies in a mouse model of K. pneumoniae infection.
Main Results:
- Phages K5-2 and K5-4 demonstrated dual host specificity for Klebsiella strains with capsular types K30/K69, K5, K8.
- Each phage possessed two ORFs encoding distinct capsule depolymerases with specific activities against K30/K69, K8, and K5 CPS.
- Purified depolymerases cleaved Klebsiella CPS in vitro, liberating monosaccharides.
- Capsule K5 was essential for phage infection, as deletion mutants were resistant to lysis.
- Phage treatment, particularly with K5-4, significantly improved survival in a mouse model of K. pneumoniae K5 infection.
Conclusions:
- Two novel Klebsiella bacteriophages, K5-2 and K5-4, and their encoded tailspike depolymerases exhibit specificities for Klebsiella capsular types K30/K69, K8, and K5.
- These phages and their depolymerases have potential applications in the serotyping of K. pneumoniae strains.
- The characterized bacteriophages demonstrate therapeutic efficacy against K. pneumoniae infections, suggesting their utility in phage therapy.
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