Feline Infectious Peritonitis (FIP) is a viral disease of cats caused by certain strains of a virus called the feline coronavirus (FeCV). Here are some key points about the mechanism of action of FIP:
- Virus replication: FeCV replicates in the intestinal epithelium and is shed in the feces15. In approximately 10 percent of cats infected with FeCV, one or more mutations of the virus can alter its biological behavior, resulting in white blood cells becoming infected with virus and spreading it throughout the cat’s body5. When this occurs, the virus is referred to as the FIPV.
- Immune response: FIP is an immune complex disease involving virus or viral antigen, antiviral antibodies, and complement3. It is not the virus itself that causes major damage but the immune response to the virus35. FeCV-infected cats usually mount an immune response through which antibodies against the virus are produced within 7-10 days of infection5. However, in cats that develop FIP, the immune response is ineffective in clearing the virus, and instead, it leads to the formation of immune complexes that deposit in various tissues, causing inflammation and damage15.
- Macrophage infection: The FIP virus is a mutated strain of FeCV that has lost its predilection for enterocytes and replicates in macrophages6. The first proposed mechanism is that FCoV-infected macrophages leave the bloodstream and carry virus into the tissues1. The virus attracts antibodies, complement, and other immune cells, leading to the formation of immune complexes that deposit in various tissues, causing inflammation and damage15.
In summary, FIP is an immune-mediated disease triggered by infection with FeCV. The virus replicates in the intestinal epithelium and is shed in the feces. In cats that develop FIP, the immune response is ineffective in clearing the virus, and instead, it leads to the formation of immune complexes that deposit in various tissues, causing inflammation and damage. The FIP virus is a mutated strain of FeCV that has lost its predilection for enterocytes and replicates in macrophages.
Citations:
[1] https://www.merckvetmanual.com/generalized-conditions/feline-infectious-peritonitis/overview-of-feline-infectious-peritonitis
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7150141/
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7114919/
[4] https://www.vet.cornell.edu/research/awards/202005/mechanism-action-doxycycline-inhibiting-feline-infectious-peritonitis-virus
[5] https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-infectious-peritonitis
[6] https://www.sciencedirect.com/topics/medicine-and-dentistry/feline-infectious-peritonitis