Clostridioides difficile S-Layer Protein A (SlpA) Serves as a General Phage Receptor

Area of Science:

• Microbiology
• Virology
• Infectious Diseases

Background:

• Clostridioides difficile infections pose a significant health challenge, with phage therapy emerging as a potential alternative to antibiotics.
• Developing effective phage cocktails requires understanding phage-host interactions, specifically the receptors phages use to infect C. difficile.
• Current knowledge of C. difficile phage receptors is limited, hindering the rational design of therapeutic strategies.

Purpose of the Study:

• To investigate the role of the C. difficile surface layer protein A (SlpA) as a phage receptor.
• To determine if SlpA is a common receptor for different types of bacteriophages targeting C. difficile.
• To provide foundational data for the rational design of C. difficile phage therapy cocktails.

Main Methods:

• Utilized the epidemic R20291 strain and its S-layer deficient mutant (FM2.5) to assess phage infection resistance.
• Employed complementation experiments by expressing different S-layer cassette types (SLCTs) on the mutant strain.
• Performed domain deletion analysis within SlpA to pinpoint specific binding regions for different phages.

Main Results:

• Absence of SlpA rendered C. difficile completely resistant to infection by specific siphages (ϕCD38-2, ϕCD111, ϕCD146).
• Complementation with specific SLCTs restored susceptibility to different phages, indicating SLCT-type specificity.
• Expression of certain SLCTs conferred susceptibility to previously non-infecting myophages, and SlpA domain deletion affected phage binding.

Conclusions:

• Surface layer protein A (SlpA) is a common and crucial receptor for a wide range of bacteriophages, including both siphages and myophages, targeting C. difficile.
• This finding is a significant step towards understanding phage specificity and will facilitate the rational development of broad-spectrum therapeutic phage cocktails against C. difficile infections.
• The study highlights the importance of SlpA in mediating phage entry, paving the way for more targeted and effective phage-based treatments.