Preventing Deadly FIP in Cats
***This article first appeared in the Fall 2024 issue of the CCAH Update newsletter.***
Feline infectious peritonitis (FIP) is a devastating disease caused by feline coronavirus. Assistant Professor Terza Brostoff and a team of UC Davis infectious disease and biomedical engineering professionals have spent the past three years creating a vaccine to prevent the often fatal condition in young cats.
In early 2021, during the height of the COVID-19 pandemic when multiple mRNA coronavirus vaccines were being developed in human medicine, laboratory technician Hongwei Liu had the idea that the same techniques could be applied to developing an FIP vaccine. Liu has spent 20 years in molecular biology, virology, and immunology and was a laboratory technician in Dr. Niels Pedersen’s groundbreaking FIP research. She approached Professor Patricia Pesavento about developing an mRNA vaccine for FIP who quickly helped pull together a multidisciplinary team.
With a background in infectious disease and vaccine development, Brostoff was chosen by Pesavento to lead the project. Joining them were Simon Anthony, Lark Coffey, Kenneth Jackson, and Hannah Savage from the School of Veterinary Medicine; Joseph Dutra, Justin Fontaine, and Dennis Hartigan-O’Connor from the School of Medicine; and Randy Carney from the Department of Biomedical Engineering. Funding was acquired from the Center for Companion Animal Health, SOCK-FIP, and the Morris Animal Foundation.
Developing a vaccine depends greatly on overall knowledge of a pathogen to determine what type of vaccine will be most effective. The team studied the development of COVID-19 mRNA vaccines and the strategies used to ensure they were successful at mounting an immune response. With that knowledge base, the research team began to adapt the process for kittens.
While a USDA-approved vaccine for FIP was developed nearly 40 years ago, it is not recommended due to the potential for antibody-dependent enhancement (ADE) later seen in immunized cats, worsening the effects of the disease. Brostoff set out to create a vaccine based on a completely different platform and strategy.
“This is a new platform that’s never been tried in cats,” Brostoff said. “There have been very few studies on mRNA vaccines in animals intended for animals.”
All coronaviruses have four structural proteins – three on the surface of the virus and one present on the inside of the virus. ADE occurs when the vaccine directs the immune system to target viral surface proteins which paradoxically enhance disease.
“A new vaccine cannot get around the antibody dependent enhancement question if we continue to use an mRNA vaccine where it is directed at one of the surface proteins,” said Brostoff.
After three years of research and development, Brostoff and her team have successfully created an mRNA vaccine that targets structural proteins inside the virus and does not cause ADE.
Many kittens in high population situations, like shelters, become infected with the coronavirus that causes FIP. Most will only sustain minor gastrointestinal (GI) illness and recover. A few, however, will not clear the virus before it becomes FIP.
“Our hope is that if we can vaccinate kittens before, or soon after, they’ve already been infected with the GI tract form of coronavirus, that they’re going to be able to make an immune response that allows them to get rid of the virus before the switch to FIP happens,” said Brostoff. “The ADE concern has been eliminated by not targeting the surface proteins on the virus.”
Most kittens begin receiving vaccinations by 6-8 weeks of age. The switch to FIP generally does not occur until 6 months to 2 years of age. If kittens receive this new FIP vaccine during the beginning immunization stage, they should be properly protected against the disease.
The team recently published the research and development results in the medical journal, Vaccines. They have filed a patent for the vaccine, and are seeking funding for initial clinical studies in kittens.
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