NOD2 Genotypes Affect the Symptoms and Mortality in the Porcine Circovirus 2-Spreading Pig Population

The nucleotide oligomerization domain (NOD)-like receptor 2 (NOD2) is an intracellular pattern recognition receptor that detects components of peptidoglycans from bacterial cell walls. NOD2 regulates bowel microorganisms, provides resistance against infections such as diarrhea, and reduces the risk of inflammatory bowel diseases in humans and mice. We previously demonstrated that a specific porcine polymorphism ( -2197A > C) augments the recognition of peptidoglycan components. In this study, the relationships between porcine -2197A/C genotypes affecting molecular functions and symptoms in a porcine circovirus 2b (PCV2b)-spreading Duroc pig population were investigated. The allele ( -2197A) with reduced recognition of the peptidoglycan components augmented the mortality of pigs at the growing stage in the PCV2b-spreading population. Comparison of allele frequencies in the piglets before and after invasion of PCV2b indicated that the ratio of -2197A decreased in the population after the PCV2b epidemic. This data indicated that functional differences caused by -2197 polymorphisms have a marked impact on pig health and livestock productivity. We suggest that -2197CC is a PCV2 disease resistant polymorphism, which is useful for selective breeding by reducing mortality and increasing productivity.