Development of an oral vaccine to protect piglets against infection with Porcine Epidemic Diarrhea Virus

Why is this project important?

PED (Porcine Epidemic Diarrhea) is a highly contagious viral disease of swine, causing diarrhea and vomiting in pigs and significant mortality in nursing piglets.

On farms that are only growing market hogs, PED causes mild diarrhea that resolves within a few days. These pigs rarely die from the disease, but may take longer to get to market. Farms that have sows and piglets are severely affected, as up to 100% of nursing piglets may die over a 3 to 5-week period, until the herd develops immunity. This can result in the loss of one month’s production of piglets. As well, producers that experience a PED outbreak may choose to clear out all of their animals, clean everything thoroughly and start over. With no effective PED vaccine currently available, the industry needs an affordable vaccine that is efficient and easy to apply.

What will researchers do?

Researchers will try two different approaches in developing a PED vaccine, both using a plant-based system to deliver it.

• First, they will devise a method to harness the power of VLPs (virus-like particles) to combat the virus. VLPs are a versatile, safe, and highly effective vaccine platform.

• The second strategy involves use of a PED virus spike protein. This protein plays an important role in limiting virus attachment and fusion to target cells.

Finally, scientists will conduct a proof-of-concept safety and efficacy trial, including piglet challenge, in a small number of pregnant sows.

What will be the benefit of this research?

To date, any potential vaccines for PED have been so expensive and cumbersome to apply that they are not widely used. This project aims to produce a PED vaccine at the lowest possible cost to farmers. Because the vaccine will be contained in plant tissue, it will also be simple to use. Farmers need only dry the plant, crumple it up and scatter it around the feed for sows. By giving one application a month before the sow gives birth and a second one two weeks later, growers should achieve a high level of protection in the milk that sows are feeding to their piglets.

Additionally, the provision of a PED vaccine in this manner will serve as a test that could pave the way for use with other pig health challenges. For pathogens that affect the GI tract of pigs, such as rotavirus (a common disease of the small intestine), this vaccine could be equally effective in protecting pig herds.

Apart from the expense to farmers when PED strikes, there is the ongoing cost of stringent practices to prevent the virus from entering their farm. While biosecurity remains a high priority, an effective vaccine could serve as an alternative to more extreme and expensive countermeasures for PED.

What has been done so far?

Thus far, researchers have been examining the structure of the PED virus spike protein and extracting pieces that could aid in vaccine development. This has allowed them to create a number of potential vaccine candidates that will soon be tested. Through the use of nanoparticles (tiny particles of matter), scientists are poised to begin a study on mice, injecting them with various vaccine candidates to immunize against disease and determine which vaccines produce a neutralizing response. Assuming that one or more of the vaccines are successful in that regard, researchers will then move on to assess their effectiveness on pigs.

Project status: Currently in progress. Results expected in 2028.

Collaborators:

• Rima Menassa, AAFC