Extracellular Actin Is a Receptor for Mycoplasma hyopneumoniae

Area of Science:

• Veterinary Microbiology
• Cell Biology
• Host-Pathogen Interactions

Background:

• Mycoplasma hyopneumoniae causes significant losses in swine production by damaging lung tissue.
• Current treatments rely heavily on antibiotics, highlighting the need for alternative strategies.
• The specific host receptors targeted by M. hyopneumoniae for lung colonization remain largely unknown.

Purpose of the Study:

• To identify novel host receptors utilized by Mycoplasma hyopneumoniae for adherence and colonization of porcine lung epithelial cells.
• To investigate the role of extracellular actin as a potential receptor for M. hyopneumoniae.

Main Methods:

• Surface biotinylation and 3D-Structured Illumination Microscopy (3D-SIM) to detect extracellular actin.
• Monoclonal antibody blocking assays to assess the role of beta-actin in M. hyopneumoniae adhesion.
• Microtiter plate binding assays, affinity chromatography, and ligand blotting to characterize M. hyopneumoniae-actin interactions.
• Characterization of actin-binding regions within the M. hyopneumoniae P97 adhesin.

Main Results:

• Extracellular beta-actin was identified on porcine epithelial cells (PK-15).
• M. hyopneumoniae demonstrated dose-dependent binding to monomeric G-actin.
• Monoclonal antibodies targeting beta-actin significantly inhibited M. hyopneumoniae colonization.
• Over 100 M. hyopneumoniae proteins were found to interact with actin, with P97 adhesin showing high-affinity binding.

Conclusions:

• Extracellular actin serves as a significant receptor for M. hyopneumoniae attachment and colonization in swine lungs.
• The P97 adhesin plays a key role in mediating this interaction through specific actin-binding regions.
• Targeting extracellular actin presents a promising avenue for developing novel interventions against mycoplasmal pneumonia in pigs.
• Extracellular actin may represent a broadly important bacterial receptor.