Animal Health, Animal Welfare, Environment & Sustainability
Producers are sick of pig diseases, and given their impact on production and performance, who can blame them.
Two of the worst offenders today are prime examples of disease fallout.
PEDV causes vomiting, dehydration, anorexia and diarrhea, leading to almost 100 per cent mortality in nursing piglets. While its effect is less severe in sows, it can inhibit their performance, leading to economic loss for producers.
PDCoV is another highly infectious virus. Like PEDV, it causes severe diarrhea, dehydration and even death, affecting pigs of all ages. The clinical signs for both conditions can be hard to spot in finishing, as their symptoms are often attributed to a feed change, ileitis or colitis.
Together, these two diseases pose a significant threat to the sector, harming pig health, animal welfare and producer revenue. Estimates for the economic harm from PEDV alone are as high as US$300,000 annually for an average farm.
In battling viruses, one of the chief weapons is vaccine. While vaccines are complex and technical, the bottom line is simple: they work. Developing effective ones is critical to safeguarding pigs from disease, so Swine Innovation Porc (SIP) is funding a project to support that effort: “Developing a bivalent vaccine for porcine epidemic diarrhea virus (PEDV) and porcine deltacoronavirus (PDCoV).”
The study is part of SIP’s recent call for proposals to address the greatest issues facing the pork sector today. Research priorities were shaped through collaboration with provincial pork organizations and industry stakeholders, ensuring the call for proposals reflects what matters most to the sector.
In response, this project will develop a subunit vaccine that offers strong protection against both viruses.
Subunit vaccines train the immune system by presenting only specific, purified components of a pathogen, such as proteins or sugars. These components are selected because they are recognized by the body’s defenses and can trigger a protective response. Instead of exposing the immune system to the entire disease-causing organism, this approach provides a targeted feature of the pathogen. This allows the immune system to learn how to identify and fight off a threat without encountering the whole pathogen.
“My interest has always been in protecting the pork industry from disease, so I keep my eyes open at all times,” says Dr. Qiang Liu, senior principal scientist with the Vaccine and Infectious Disease Organization (VIDO) at the University of Saskatchewan. “I monitor the disease surveillance reports from Ontario Pork each month, and I noticed that the case numbers were steadily increasing for both PEDV and PDCoV.”
Although enhanced biosecurity measures are effective in containing virus spread to some extent, this approach has not been successful in eradicating the disease, making the availability of effective vaccines the ultimate solution. On top of this, additional variants could emerge, as was demonstrated during the SARS-CoV-2 pandemic.
Just as timing is critical for containing a virus when it hits the barn, the launch of this study is timely for producers.
“The current vaccine landscape for these two diseases is bleak,” Dr. Liu says. “The one that exists for PEDV does not provide complete protection, and there is no licensed vaccine for PDCoV. I can’t find any research out there on a bivalent vaccine either, which makes this a novel project.”
Since PDCoV is milder than PEDV, Dr. Liu thinks people may not take it seriously enough, but he notes that co-infection rates and disease consequences for both are worse than first thought.
Like all good science, this study will evolve in stages to design a bivalent vaccine, progressing systematically from mice to piglets to sows.
“We will begin with mouse and piglet trials to find the best vaccine formulation before proceeding with trials on sows,” Dr. Liu says. “After vaccinating the sows, we will collect 12 neonatal piglets from each sow and challenge them with the two viruses. In doing so, we can evaluate the level of protection conferred by the vaccine.”
To ensure that the final version of the vaccine is available to industry, researchers are collaborating with potential manufacturers by sharing results and technology.
Vaccine research involves many challenges, as finding a formulation that produces a strong immune response is no easy task. But given the many potential benefits of doing so, which include enhancement of animal welfare, better mental health for barn workers and reassurance of consumers, Dr. Liu is excited at the prospects.
“This is sometimes overlooked, but an effective vaccine against PEDV and PDCoV also benefits the environment,” he says. “Because both viruses trigger higher feed and energy inputs for sows, they increase greenhouse gas emissions per unit of pork.”
The three-year term of this study won’t allow for on farm testing of the vaccine, but that remains a key objective given the stakes.
“To put a dollar number on the 2013-14 PEDV outbreak in the U.S., where they lost 10 per cent of the pig population, it would be anywhere from $900 million to $1.8 billion,” says Dr. Liu. “If we can play a part in reducing those numbers, we’ve done our jobs.”