Developing Innolysins Against Campylobacter jejuni Using a Novel Prophage Receptor-Binding Protein

Area of Science:

• Microbiology
• Bacteriology
• Food Safety

Background:

• Campylobacter contamination in poultry is a primary source of global foodborne gastroenteritis.
• Existing treatments necessitate the development of novel antibacterial agents.
• Previous research established Innolysins (endolysin fused to receptor binding protein) as effective against Escherichia coli.

Purpose of the Study:

• To expand the Innolysin concept for targeting Campylobacter jejuni.
• To identify and characterize a novel receptor binding protein (RBP) for C. jejuni phages.
• To construct and evaluate Innolysins Cj for their antibacterial efficacy against C. jejuni.

Main Methods:

• Identified H-fiber from a CJIE1-like prophage as a novel RBP for C. jejuni.
• Constructed Innolysins Cj by fusing H-fiber to phage T5 endolysin.
• Assessed antibacterial activity of Innolysins Cj in vitro and on contaminated chicken skin under refrigeration.

Main Results:

• Innolysin Cj1 demonstrated bactericidal activity against diverse C. jejuni strains in vitro, achieving up to 1.30 log reduction.
• Innolysin Cj5 was selected as a promising candidate from a library of Innolysins Cj.
• Both Innolysin Cj1 and Cj5 significantly reduced C. jejuni on contaminated chicken skin (1.63 and 1.18 log reduction, respectively).

Conclusions:

• Innolysins Cj are effective antibacterials against Campylobacter jejuni, both in vitro and in situ on food products.
• The H-fiber RBP component recognizes a novel receptor distinct from those targeted by typical lytic phages.
• Further exploration of Campylobacter phage RBPs could expand the arsenal of Innolysins for combating Campylobacter infections.