Genomic survey of polymorphisms in pattern recognition receptors and their possible relationship to infections in pigs

Recent progress in the accumulation of pig genomic information has enabled us to comprehensively explore polymorphisms in pig genes. One of our targets for exploration has been the genes encoding molecules related to pathogen recognition, such as pattern recognition receptors (PRRs). PRRs play a role in the innate immune system, and possess various members such as Toll-like receptors (TLRs), NOD-like receptors (NLRs), RIG-like helicases (RLHs), and C-type lectin-like receptors (CLRs). PRRs are required for the monitoring of pathogens; therefore, polymorphisms in PRRs may influence molecular functions such as ligand recognition. There have been many studies on the relationship between polymorphisms within PRR genes and disease susceptibility in humans and mice. Our studies have revealed that porcine PRR genes possess many nonsynonymous polymorphisms, particularly in regions encoding the ectodomains of TLRs localized on the cell surface. The genes encoding TLRs located on the membrane of intracellular compartments, and cytoplasmic PRRs such as NLRs and RLHs, also possessed nonsynonymous polymorphisms. Several observations indicate that there are relationships between polymorphisms in PRR or related genes and disease susceptibility in livestock animals including pig. Such information may contribute to breeding aimed at disease resistance, and effective vaccine design.