Imagine if the pigs in your barn had immune systems better able to fight off disease without vaccines and antibiotics?
Such animals may seem like fantasy, but a recent research discovery suggests it may well be possible.
And, if such animals are bred it could dramatically impact swine disease management.
What is creating the prospect of what might be seen as ‘hyper-immune’ animals is work at the University of Saskatchewan (USask) where a research team has discovered a bacteria-killing molecule that enhances a pig’s immune system response.
USask researchers recently published a paper in Scientific Reports that identified a promising alternative for controlling infectious diseases such as swine dysentery. Porcine β-defensin 5, or pBD-5, is a host defence peptide (HDP) that may help to reduce the industry’s reliance on antibiotics.
Also known as antimicrobial peptides, HDPs are naturally occurring, innate immune molecules found in all complex living organisms. The antimicrobial properties of HDPs allow them to play a vital role in combating pathogens such as bacteria and viruses.
Dr. Arthur Nery Finatto (DVM), a PhD student based at the Western College of Veterinary Medicine (WCVM) and the research paper’s lead author said the research is encouraging because it indicates the disease responses of pigs can be enhanced through exploring the properties of this new molecule.

Finatto told Prairie Hog Country the discovery was initially made as the team worked on swine dysentery, a production-limiting disease that leads to significant economic losses for swine producers.
At present there’s no effective vaccine for the infectious disease, and the only treatment option is antibiotic drugs.
Finatto said pBD-5 holds promise as an alternative to traditional antibiotic treatments.
The use of antibiotics is something Finatto said are currently needed for swine health, citing the need for animal welfare reasons — “not letting animals suffer from treatable diseases.”
But the new discovery may lead to a more naturally occurring answer to swine dysentery.
Development of the recently discovered novel molecule is important because it is naturally produced by the pig, he explained.
Finatto said it was initially discovered after noticing control groups of pigs became infected at different rates, some as soon as day one, some not at all. In analyzing cultures from the gut of the control animals, the individuals showing the highest levels of pBD-5 were the ones which staved off the disease best.
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 defence molecules known for their antimicrobial properties.
Building on this discovery, Finatto and the team synthesized the peptide in the lab.
When the researchers exposed pBD-5 to various bacterial strains, the synthesized peptide demonstrated broad-spectrum antimicrobial activity—effectively inhibiting bacterial growth.
Finatto said they were excited to see that when they exposed pig immune cells to pBD-5 they saw changes in gene expression.
“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,” he said in a UYSask release.
But, a better option may be to selective breed lines which have naturally high levels of the protein — essentially creating pigs with stronger innate immunity, added Finatto.
Given that pigs reproduce rather quickly, Finatto said a line of animals with the enhanced immune system based on selecting for the discovered protein might take only “three to five years,” adding it would be a case of natural selection rather than actually going in and modifying the pig’s genes.
“We’d be selecting pigs that have this trait in their genome,” he said. •
— By Calvin Daniels