The influence of age and genetics on natural resistance to experimentally induced feline infectious peritonitis

Pedersen NC1, Liu H2, Gandolfi B3, Lyons LA3.

  1. Center for Companion Animal Health, School of Veterinary Medicine, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA. Electronic address:
  2. Center for Companion Animal Health, School of Veterinary Medicine, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.
  3. Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA; Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, Columbia, MO 65211, USA.

Something about the study and its significant findings:

This investigation spanned over three years between 2010-2013 and involved cats gathered from several past and present studies

Important information on FIP gained by this study:

1) We confirmed that random bred cats have a significant degree of natural resistance (immunity), something not previously documented.

2) Other host, viral and environmental factors that can affect natural resistance were eliminated as variables in the study, thus demonstrating the importance of eliminating or minimizing practices and procedures that might inhibit natural resistance.

3) We demonstrated that immunity was not always long-lasting, something previously shown for feline enteric coronavirus infection but not for FIP. This may be one explanation for FIP in older cats.

4) We provided evidence for potential genetic resistance factors in random bred cats, just as we demonstrated earlier for naturally occurring FIP in pedigreed Birmans.  However, these associations were complex (polygenic) and different than what we observed in Birmans, indicating that as with Rome, many roads lead to FIP Resistance.

5) Cats that maintained strong and long-lasting immunity are being used to create a colony of cats to study genetic resistance factors.  If such heritable resistance factors exist, they could be introduced into pedigreed cat breeds.

6)  Information and tissues from cats that both died and survived FIP virus infection have been used to conduct two in-press publications concerning the manner in which the virus affects the host and how host immunity affects the virus. Knowledge of how FIP virus is able to evade the immune system in most cats is vital to developing targeted drug therapies.

7) We obtained and preserved materials in the form of specific tissues, RNA and DNA for future studies.

8) We emphasized again the difficulties in conducting complex genetic studies with relatively small cohorts of cats with limitations in the genetic tools that are available for this species.

Take home message:

Many cats have a natural immunity to FIP, which is strong in some individuals and tenuous in others. Natural immunity is affected by age at the time of infection and possible genetic factors. Combining these findings with information gleaned from previous studies, we conclude that the most effective current tool in preventing cases of FIP is to limit the severity of feline enteric coronavirus (FECV) exposure in young kittens and minimize stresses that may inhibit natural resistance factors during the crucial period when mutant FECVs (i.e., FIP viruses) first occur. – N. C. Pedersen


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