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Interpretive Summary: 129 Genomic Relationship Between PRRSV Wild-type Infection and PRRSV Vaccination for Antibody Response and Reproductive Performance

By Caitlin Vanderohe

The selection of swine for production typically occurs in a purebred, high health, biosecure nucleus herd. However, this selection and management system limits industry capabilities to genetically select for traits the confer disease resistance and antibody response to pathogen challenges. One of these traits that has been proposed as an indicator for improved reproductive response to Porcine Reproductive and Respiratory Syndrome (PRRSV) is the sample to positive ratio. However, while investigators have demonstrated genetic utility of this trait, the S/P ratio needs to be assessed after PRRSV vaccination or outbreak and few have demonstrated the applicability of this ratio to crossbred performance, which may limit its utility. Therefore, recent work, published in the Journal of Animal Science, by Sanglard et al. assessed the genetic relationships between the S/P ratio and performance in a purebred population that experienced a PRRSV outbreak and a crossbred population that underwent PRRSV vaccination.

Data collected demonstrated that S/P ratio after a PRRSV outbreak was genotypically correlated with S/P after vaccination, and both of these traits are influenced by genes in the MHC class II region on Sus Scrofa Chromosome 7. Additionally, S/P after vaccination was favorably correlated with reproductive performance in non-infected purebred sows and PRRSV-infected purebred sows. This study also showed that associations between antibody response and reproductive performance; a specific heterozygote genotype in this MHC region was associated with improved antibody response and improved body composition in PRRSV-exposed sows. Overall, this study demonstrated the potential challenges and utility of genetic selection based on antibody response in commercial swine production.