Antimicrobial Peptides and Salivary Proteins

Antimicrobial agents from living beings hold the promise of helping with efforts to reduce infections. Two separate research efforts indicate sufficient potential to warrant more research and, hopefully, application: One uses a genetically engineered variant of a protein found in human saliva to reduce Candida infections; the other applies the antimicrobial peptides found in fish gills to kill E. coli pathogens.

Boston University professor, Dr. Frank Oppenheim led a team that genetically engineered a variant of the human saliva protein, histatin 3, which is known to have antimicrobial—both antifungal and antibacterial—properties. The study, Anti-candidal activity of genetically engineered histatin variants with multiple functional domains, demonstrated that duplicating active functional domains in the amino acid sequence can enhance their antifungal properties. Histatin preparations have already demonstrated their effectiveness in reducing Candida infections in AIDS patients. Antibacterial and antifungal mouthwash is one possible application. Genetically enhanced histatins could also be used to address skin infections.

Meanwhile, researchers at Worchester Polytechnic Institute in Massachusetts hope to adapt the fish gill antimicrobial peptide to create bacteria-killing surfaces. Such surfaces may help reduce healthcare-acquired infections. Fish have evolved powerful defenses, including the antimicrobial peptide Chrysophsin-1 to trap and kill water-borne pathogens before they enter the bloodstream. The researchers’ study, Creating Antibacterial Surfaces with the Peptide Chrysophsin-1 is part of their effort to understand the biochemical mechanics of the pathogen-trapping process.

Using two different methods to attach the peptide to silicon and gold surfaces, the researchers then measured how well the bound peptides killed E. coli, a bacterial pathogen. When the peptides were absorbed directly into the gold and silicon crystals, and thus were lying flat on the surface, they killed 34 percent of the culture’s bacteria. However, when the peptides were glued so that the peptides seemed to be standing on their ends, they killed 82 per cent of the bacteria. Next on their research agenda is to adapt the process to titanium, stainless steel, and plastic, materials that are commonly used in food preparation and healthcare.

The peptide Chrysophsin-1, found in fish gills, is being studied for its antimicrobial properties and possible role in infection reduction in healthcare settings.