W18-010: Are interferon-gamma polymorphisms a risk factor in FIP development – a large cohort study
(Winn-funded Grant Final Report )
Principle Investigator: Dr. Emi Barker
Feline Infectious Peritonitis is a serious, generally fatal disease of cats. Until very recently no effective treatment has existed, and even now those treatments are generally unavailable to the public. Despite widespread exposure to feline enteric coronavirus and production of mutant FIPV strains, only a small number of cats develop clinical FIP. It has been suggested that mutations in immune system genes (ie interleukins and interferons) may play a role in the pathogenesis of FIP.
The goals of the study were to determine the interferon gamma (IFN-g) gene sequence within a population of cats with FIP; to determine the interferon-gamma gene sequence within the general non-pedigree cat population, and to determine the relative risk conferred by specific interferon-gamma gene sequences in the development of FIP.
Non pedigreed cats were enrolled to minimize effect of breed on genetic changes and because they represent most cases of FIP.
DNA was extracted from 264 cheek swab samples collected from non-pedigree cats from the Bristol Cats study, and from 59 samples of tissue or effusion banked from cats confirmed to have FIP.
A polymorphism in the IFN-g gene was noted to be present in the population that was associated with a decreased risk of FIP development. This mutation was present in 16% of the FIP population and 34% of the general population.
The results of this study suggest that polymorphisms within the IFN-g gene are present in cats and may be associated with a differing risk of FIP. However, the less common sequence was associated with a lower risk of FIP, and both sequences were found with relatively high frequencies in both populations of cats. As such, screening for increased FIP risk or selective breeding programs on the basis of this polymorphism are likely impractical. It is possible that mutations in other immune genes, alterations in the genes affecting IFN-g expression, or combinations of multiple mutations may be responsible for the varying immune response to FIP.
Barker, E.N., Lait, P., Ressel, L., Blackwell, E.-J., Tasker, S., Helps, C.R. (2020) Evaluation of interferon-gamma polymorphisms as a risk factor in feline infectious peritonitis development in non-pedigree cats – a large cohort study Pathogens 9: 535 DOI:10.3390/pathogens9070535