A vaccine to prevent FIP in its infancy.

Original article on dvm360.com, published 18.3.2020.

Researchers at Colorado State University want to stop the feline enteric coronavirus before it has a chance to mutate to the feline infectious peritonitis virus.

A new candidate in the fight against feline infectious peritonitis (FIP) may soon enter the scene. Researchers at Colorado State University (CSU), funded by the Morris Animal Foundation, are developing an oral vaccine to beat the disease by targeting feline enteric coronavirus (FECV) - a highly contagious and common virus that can accidentally mutate to FIPV.

"Vaccination attempts in the past have been directed against the FIP, but it is too late," said Gregg Dean, DVM, PhD, head of the Department of Microbiology, Immunology and Pathology at the College of Veterinary Medicine and Biomedical Sciences. dvm360. "We know that enteric coronavirus is replicating at an amazing rate." Thus, it is likely to mutate into the virus that causes FIP - so there is more going on inside the cat than it is transmitted between cats. If we could control this replication, we could prevent the mutant from forming. "

It's all about the gut

As a first step in understanding what the vaccine would have to do to stimulate a protective immune response against FECV, Dr. Dean and his team studied cats that were infected naturally with the disease, specifically by monitoring their mucosal immune responses. "The enteric virus is quite limited in where it replicates, and that is, as we know, in the intestinal tract," he explained. "Understanding the immune response at this site is therefore critical."

Vaccine design reflects this very finding. The vaccine will be given orally and includes Lactobacillus acidophilus, a probiotic found in some foods and in the gastrointestinal tract of many animals. "The role of the probiotic is crucial," said Dr. Dean. "Some probiotics stimulate the immune system naturally, and thanks to the combination of antigens from feline coronavirus with the natural immunostimulatory activity of the probiotic, we hope to elicit a protective and lasting immune response." He explained that the effect of the probiotic is enhanced by being alive and replicating. "It also produces antigens - in our case feline coronavirus antigens - so it's very economical," Dr. Dean. "We don't have to use expensive processes to produce large amounts of antigen." We use the natural activity of bacteria. "

Dr. Dean and his team plan to launch the first trials of the effectiveness of the FECV vaccine this fall. "We give the vaccine to cats in a colony environment where enteric coronavirus circulates naturally. We will take new kittens, vaccinate them, and then see if they become infected with FECV, "he said. "Almost every cat, and probably even every cat in this colony, is infected."

Disease recognition

Meanwhile, Dr. Dean is leading another study funded by the Morris Animal Foundation with a different but related goal: to develop a new diagnostic test for FIP that is accessible, inexpensive, and fast. "As we move closer to real, viable FIP treatment options, an accurate diagnostic test will be an important part of this decision-making process," he explained. "Early diagnosis will be important if effective treatment is available."

Instead of focusing on the cat's immune response, or looking for the virus itself, Dr. Dean and his team investigate specific biomarkers that are unique to FIP infection. They have identified 18 proteins that so far appear to be common in cats with FIP and are in the process of validating them. If the test is successful, the patient will only need a blood sample. "We still have a lot of work to do, but it is our top priority," he said.

We have a lot of work to do

With these exciting prospects for cat health on the horizon, Dr. Dean praised the past and present work of his veterinary colleagues: "There are a lot of people who work hard to solve these important problems for cats, and it is the excellent work of this community that leads us all to a common goal."

Sarah Mouton Dowdy, a former dvm360.com editor, is a freelance writer and editor in Kansas City, Missouri.