Molecular characterization and association analysis of porcine interferon regulatory factor 1 gene

Interferon regulatory factor 1 (IRF1) is a member of IRF-family that was discovered to activate promoters in type I interferon (IFN) genes. It is shown to play functionally diverse role in the regulation of the immune system. In this report, the porcine IRF1 cDNA were cloned and a 7500 bp genomic DNA structure was identified. The putative IRF1 protein included 322 amino acids. Alignment and phylogenetic analysis of the predicted porcine IRF1 amino acids sequence with its homologies of other species show high identity (over 88%). Tissues expression of IRF1 mRNA was observed by RT-PCR, the results revealed IRF1 gene expressed widely in all analyzed tissues. Using the radiation hybrid panel, the porcine IRF1 gene was mapped to porcine chromosome 2 and closely linked to the locus IL4 (LOD = 7.09, 57cR). A SNP in exon2 of porcine IRF1 gene was demonstrated by sequencing and PCR-RFLP analysis. The further association analysis indicated that the SNP was significant associate with level of IFN-γ (day 20) in serum (P = 0.0001) and the ratio of IFN-γ to IL10 (day 20; day 35) in serum (P = 0.0165; P = 0.0095). The results suggested that the porcine IRF1 gene is strong candidate gene for these immune traits in pig.