Farmscape for April 11, 2022

Efforts to develop a protein-based subunit vaccine to prevent Lawsonia intracellularis are showing progress.
Lawsonia intracellularis is a common bacteria that reduces the ability of the intestines of pigs to absorb nutrients, resulting in slower weight gain.
Researchers with the Western College of Veterinary Medicine and the Vaccine and Infectious Disease Organization are using various techniques to identify antigens that can be used in the development of safe and effective subunit vaccines to prevent this infection.
Kezia Fourie, a PhD Student with the Western College of Veterinary Medicine, says the goal is to identify antigen candidates that the immune system will recognize and that will work well in a vaccine.

Clip-Kezia Fourie-Western College of Veterinary Medicine:
Lawsonia is a really unique bacteria and that means we just don't know a whole lot about how it actually causes an infection and, if you don't know what causes an infection, it's really hard to prevent the infection in the first place.
It's also a very difficult bacteria to work with in the lab because it has to infect a cell before it can even grow so there's only a few labs around the world who can actually grow it so that just creates a whole new layer of challenges.
You might know that this bacteria uses a specific protein to cause an infection and you can create a vaccine that targets that protein so we decided to use a technique called reverse vaccinology.
This non-traditional method allows you to identify those proteins.
What you do, in terms of Lawsonia, is let the bacteria interact with an intestinal cell and then they also use antibodies from an infected pig and they look at what Lawsonia proteins are targeted by those antigens, so antibodies from infected animals but also interact with the host cell.
Then you can identify those proteins through a process called mass spectrometry and then those can be antigen candidates for your vaccine.

Fourie says, once these candidates are identified, the next step is to come up with formulations that will induce the best immune response.
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Bruce Cochrane.

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