Targeting Type IV Secretion System Proteins to Combat Multidrug-Resistant Gram-positive Pathogens

Area of Science:

• Microbiology
• Immunology
• Vaccinology

Background:

• Antibiotic resistance spread by conjugative plasmids in gram-positive pathogens necessitates novel treatments.
• The protein TraM, encoded by the pIP501 conjugative plasmid, is investigated for its potential role in combating infections.

Purpose of the Study:

• To evaluate the protein TraM as a potential vaccine candidate against gram-positive pathogens.
• To assess the efficacy of anti-TraM antibodies in vitro and in vivo.

Main Methods:

• In vitro opsonophagocytic killing assays using anti-TraM antiserum.
• Western blot and opsonophagocytic inhibition assays to confirm antibody specificity.
• Conjugative transfer experiments to determine TraM's role in plasmid transfer.
• In vivo immunization studies in mice to evaluate vaccine efficacy.

Main Results:

• Anti-TraM antiserum demonstrated in vitro opsonophagocytic killing of pIP501-carrying strains.
• Antibodies showed cross-reactivity against clinically relevant enterococcal and staphylococcal strains.
• TraM was confirmed as essential for pIP501 conjugative transfer.
• Immunization with TraM or anti-TraM antiserum significantly reduced bacterial liver burden in mice.

Conclusions:

• TraM is essential for conjugative transfer of the pIP501 plasmid.
• TraM is a promising vaccine candidate against enterococci and other gram-positive pathogens.
• Targeting TraM offers a potential strategy to combat antibiotic resistance.