An intronic polymorphism in the porcine IRF7 gene is associated with better health and immunity of the host during Sarcocystis infection, and affects interferon signalling

• Published in: Animal genetics Vol. 42; no. 4; pp. 386 - 394
• Main Authors: Broke, A., Matika, O., Wilson, A. D., Anderson, J., Morin, A.-C., Finlayson, H. A., Reiner, G., Willems, H., Bishop, S. C., Archibald, A. L., Ait-Ali, T.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.2011; Wiley Subscription Services, Inc
• Subjects: Animals; Base Sequence; Cloning, Molecular; DNA Primers - genetics; Gene Frequency; Genes; genetic association; Genome-Wide Association Study; Infections; innate immunity; Interferon Regulatory Factor-7 - genetics; intron; Introns - genetics; IRF7; Linear Models; Molecular Sequence Data; Phenotype; pig; Polymorphism; Reverse Transcriptase Polymerase Chain Reaction; Sarcocystis; Sarcocystis miescheriana; Sarcocystosis - genetics; Sarcocystosis - veterinary; sarcosystis; Sequence Analysis, DNA; Signal Transduction - genetics; Signal Transduction - immunology; Sus scrofa - genetics; Sus scrofa - immunology; Swine; Swine Diseases - genetics; Swine Diseases - parasitology
• ISSN: 0268-9146; 1365-2052
• DOI: 10.1111/j.1365-2052.2010.02154.x

Summary Interferon regulatory factor 7 (IRF7), as a key regulator of type I interferon response, plays an important role during innate response against viral infection. Although well conserved across species, the structure of IRF7 and its function during parasite infection are not well documented in farm animals, such as the pig. To bridge this gap, we have determined the porcine IRF7 gene structure and identified two intronic single nucleotide polymorphisms (SNPs), SNP g.748G>C and SNP g.761A>G, in commercial pig breeds. The distribution of SNP g.761A>G in multiple breeds suggested that it was in Hardy–Weinberg equilibrium and allowed us to map it at the top of SSC2. We found that during Sarcocystis miescheriana infection, the G allele was associated with high lymphocyte levels (P < 0.02), reduced drop in platelet levels (P < 0.002) and IgG1‐Th2‐dominated response (P < 0.05). This suggests that the G allele was associated with better health and immunity of the host during Sarcocystis infection. Furthermore, we have also provided suggestive evidence that the G allele of SNPc.761A>G enhances the transactivation activity of IRF7, possibly by improving IRF7 transcript splicing of intron‐3. These findings would suggest that IRF7, as a transcriptional regulator, is involved in the defence mechanism against a larger spectrum of pathogens, and in more host species, than initially anticipated.