Genetic and biological factors influencing host response to Porcine Reproductive and Respiratory Syndrome virus in growing pigs.

摘要

Porcine Reproductive and Respiratory Syndrome (PRRS) is a disease of major importance in the swine industry due to its economic impact and its negative effects on animal welfare. PRRS has been estimated to cost the US swine industry alone ;NVSL was found to be a more virulent isolate than KS06, but host genetic response to PRRSV influencing peak serum viremia, weight gain, and S:P is expected to be similar during infection with either of these isolates, as evidenced by the estimated strong positive genetic correlations of response to NVSL infection with KS06 infection. A SNP (WUR10000125) that was previously found to be associated with viral load and weight gain under PRRSV infection with the NVSL isolate was found to be associated with viral load and peak viremia in pigs infected with NVSL or KS06; however, there was no observed effect on weight gain in KS06 infected pigs. This suggests the effect of the quantitative trait locus (QTL) marked by WUR may be dependent on the virulence of the PRRSV variant. The relationships between serum viremia and weight gain over the span of three days three-day weight gain changed throughout the course of infection, and were particularly different for pre- and post-peak serum viremia levels. A dynamic relationship was also observed between S:P and serum viremia or three-day weight gain, suggesting that in order to fully explore the relationship between different PRRS response traits, they need to be considered at multiple time points throughout infection. Three QTL, located in the major histocompatibility complex (MHC), were found to be associated with S:P. These QTL were not associated with serum viremia levels or weight gain, suggesting that the genetic correlations of S:P with these traits are due to regions outside of the MHC. Peak viremia, S:P and weight gain during PRRSV infection were identified as traits which have the most potential for successful selection for improved response to PRRSV infection due to high heritability estimates, high genetic correlations with PRRS serum viral load and the ability to measure these traits relatively easily in an industry setting.