A recent blog post described a group of researchers who identified genetic changes (SNPs) within the interferon gamma (IFNg) gene leading to changes in resistance and susceptibility to feline infectious peritonitis (FIP). FIP remains a leading cause of mortality in cats worldwide, and further information on its cause and prevention will allow more targeted prevention and potentially therapy.
The basis of this work is single nucleotide polymorphisms (SNPs); small changes in genes that lead to changes in function and regulation.
A second study by the same group continued this research in 71 FIP+ and 93 FECoV+ control cats, with a similar age and breed distribution to the first paper. All cats were negative for FIV and FeLV and had FIP confirmed by histopathology.
This study looked for SNPs in the tumor necrosis factor-alpha (TNFα) and fCD209 (a protein allowing viruses to enter cells) genes using similar methodology to the first paper. The group was able to identify one SNP in the regulatory region of TNFα and two within the introns of fCD209 associated with FIP resistance. They also identified a SNP causing a premature stop codon in the extracellular domain of fCD209 associated with FIP susceptibility, as well as one within an intron of the same gene.
An interesting finding in this second paper was the correlation between number of SNPs and disease susceptibility/resistance. Cats with more SNPs associated with resistance had correspondingly lower rates of FIP, with a similar trend in susceptibility SNPs. This suggests that cats may be identified as having varying levels of resistance to FIP.
The high mutation rate in FECoV has hindered recent attempts to create an effect FIP vaccine. Similarly, treatments for FIP have largely been ineffective. The current papers provide insight to a population genetics based approach to FIP management. Screening potential breeding animals using “SNP-Chips” (which allow high throughput screening of multiple SNPs simultaneously) and selecting those most likely to possess disease resistance provides a feasible route to decreasing FIP prevalence (especially in those breeds or lines known to have a higher rate of FIP). (MRK)