Unpuzzling Friunavirus-Host Interactions One Piece at a Time: Phage Recognizes Acinetobacter pittii via a New K38...

Area of Science:

• Microbiology
• Virology
• Bacteriology

Background:

• Acinetobacter pittii is a significant nosocomial pathogen, often exhibiting multidrug resistance.
• Bacterial capsules are key virulence factors, protecting against phage predation and host immune responses.
• Understanding phage-host interactions is crucial for developing effective phage therapy against Acinetobacter.

Purpose of the Study:

• To isolate and characterize a novel phage targeting Acinetobacter pittii.
• To investigate the phage's mechanism of action, particularly its interaction with bacterial capsules.
• To explore the potential of phage-derived enzymes as novel antibacterial agents.

Main Methods:

• Isolation and characterization of a novel Acinetobacter pittii-infecting phage (vB_Api_3043-K38) from sewage.
• Genomic analysis of the isolated phage.
• Biochemical characterization of the phage's tailspike protein and its depolymerase activity against Acinetobacter K38 capsules.
• Assessment of phage and depolymerase activity against bacterial resistance to phage predation and host serum complement.

Main Results:

• Isolation of the Fri1-like phage vB_Api_3043-K38 with a 41,580 bp dsDNA genome.
• Identification of a novel tailspike with K38 depolymerase activity, specifically degrading Acinetobacter K38 capsules.
• Demonstration that K38 depolymerase treatment renders bacteria resistant to phage predation.
• Observation that K38 depolymerase treatment increases bacterial susceptibility to host serum complement, though it does not synergize with antibiotics.

Conclusions:

• A novel phage-encoded K38 depolymerase was characterized, targeting a previously unexploited Acinetobacter capsule type.
• This depolymerase advances the understanding of phage-host interactions in Acinetobacter.
• The K38 depolymerase shows promise as a potential antibacterial agent against drug-resistant Acinetobacter.