Finatto said pBD-5 holds promise as an alternative to traditional antibiotic treatments—an important factor in global efforts to address the growing threats of antimicrobial resistance and food security for the world's increasing population.
"We currently need antibiotics for animal welfare reasons—we cannot let the animals suffer from treatable diseases," said Finatto. "But the development of this novel molecule is important because it is naturally produced by the pig. We can selectively breed animals that produce more of this protein—essentially creating pigs with stronger innate immunity."
The team's discovery was inspired by their observations of how some pigs developed severe clinical signs of swine dysentery while others in the same herd remained relatively unaffected by the disease.
Through detailed genomic analysis, the researchers identified a region of the swine genome associated with this resilience, which encoded a peptide resembling β-defensins, a family of host defense molecules known for their antimicrobial properties.
Building on this discovery, Finatto and the team synthesized the peptide in the lab. USask researchers completed this challenging task in collaboration with chemistry scientists at the Université du Québec à Montréal. When the researchers exposed pBD-5 to various bacterial strains, the synthesized peptide demonstrated broad-spectrum antimicrobial activity—effectively inhibiting bacterial growth.
"What was really exciting was that when we exposed pig immune cells to pBD-5, we saw changes in gene expression," added Finatto. "The pig's own immune system began to express different immune-related genes, which suggests that pBD-5 not only has antimicrobial properties but also acts as an immunomodulator."
As well, the researchers observed that pBD-5 caused downregulation (a reduction of response) of certain genes in macrophages—immune cells that play a central role in the inflammatory response. By modulating the immune response, pBD-5 could help reduce the damage caused by swine dysentery and other production-limiting diseases.
In addition, pBD-5 appeared to enhance the activity of mitochondria in immune cells, particularly in cells responsible for antibody production. This finding suggests that adding pBD-5 to vaccine formulations could improve their ability to produce antibodies and to provide strong, long-term immunity to pigs.
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