Development of multivalent vaccines for porcine epidemic diarrhea (PED)

Why is this project important?

Porcine epidemic diarrhea (PED), caused by PEDV, continues to be a significant threat for the swine industry in Canada and worldwide. The disease is characterized by vomiting, diarrhea, dehydration, and anorexia, causing up to 100% mortality in suckling piglets. It also has a negative impact on the performance of sows.

Pigs surviving PEDV infection have been reported to demonstrate reduced growth rates in the nursery and growing phase. Pigs infected with PEDV during the growing phase tend to have a mild clinical response, such that age to market is typically reduced by at least one week.

These productivity outcomes result in higher feed and energy inputs for the sow herd and growing pigs per unit of pork produced, thereby contributing to an increase in environmental and greenhouse gas emissions per unit of pork. Since PED is a sporadic disease in Canada and the US, often recurring in herds every three to four years, the environmental impact per unit of pork product is ongoing.

While increased biosecurity has been employed to reduce outbreaks and “feedback” autogenous immunization approaches have been used to control infections following an outbreak, the disease has not been eradicated and continues to circulate, particularly in the northern United States and western Canada. Autogenous vaccines are prepared through the isolation and destruction of microorganisms in infected animals and used to provide immunity to those same animals.

At present, there are no safe and effective vaccines available for swine producers. Consequently, science needs to optimize an existing inactivated vaccine to ensure a timely supply to swine producers and to develop a subunit vaccine that can provide protection against two PEDV strains that are currently circulating in North America. A subunit vaccine is a vaccine that contains purified parts of the pathogen that are necessary to elicit a protective immune response.

What will be the benefit of this research?

PED can cause enormous economic losses. As per an estimate in 2016, the loss could be as high as US$300,000 per year for a single 700-sow farrow-to-finishing herd. 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.

In order to help provide Canadian pork producers with a PEDV vaccine, this project is optimizing the production and formulation of the vaccine using processes aligned to commercial production. These processes meet the requirements of the regulatory authorities and facilitate the technology transfer of the production process to potential manufacturers of the vaccine, including VIDO’s Vaccine Development Centre. VIDO is the Vaccine and Infectious Disease Organization at the University of Saskatchewan.

As outbreaks can result in nearly 100% mortality in neonatal pigs, there is a significant animal welfare concern that may be amplified given society’s sensitivity to welfare issues affecting young animals. Certainly, the high mortality rate can also be mentally devastating for farrowing barn workers. The development of a vaccine that is effective for PEDV could contribute to a successful eradication strategy and protect neonates from high morbidity and mortality outcomes.

What will researchers do?

At five weeks of age, piglets will be injected with two doses of vaccine twice with a four-week interval, and saline will be injected as a control. Eight animals will be randomly allocated into the trial groups to allow for statistical analyses. Blood and oral swab samples will be collected on day 0, two weeks after the first dose and three weeks after the second dose.

To optimize the inactivated PEDV vaccine developed by VIDO, researchers will improve virus production efficiency by utilizing cell factories, which are single-celled microorganisms or plant cells optimized to produce the virus more efficiently. They will also test two additional adjuvants (elements added to vaccines in order to improve immune response). These efforts will allow for a smooth transfer to VIDO’s Vaccine Development Centre for small-scale production.

Project status: Project launched in 2023

Collaborators:

• Dr. Colin Strauss, University of Saskatchewan

  
  

• Dr. Heather Wilson, University of Saskatchewan

  
  

• Dr. François Meurens, National Veterinary, Agri-Food and Food School of Nantes-Atlantique