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Continued losses to the pig industry from porcine reproductive and respiratory syndrome (PRRS) make it imperative to search for alternative PRRS control practices. This grant proposes to use state-of-the-art whole genome association analyses to identify the genetic determinants of resistance/susceptibility of commercial U.S. swine to PRRSV infection. <P> We will address PRRS coordinated agricultural project (CAP2) Objective 3: Characterize host factors that contribute to PRRS disease resistance and susceptibility (host genetics). The primary samples to be tested will be those collected through the NPB funded PRRS Host Genomic Consortium (PHGC), a national effort to collect phenotypic data to assess the role of genetics in determining pig resistance to PRRSV infection and related pathology and growth effects. DNA samples from PHGC pigs will be genotyped with the newly developed 60K single nucleotide polymorphism (SNP) chips.<P> Obj.3.1. Addresses research on immunity and vaccination using gene expression analyses to reveal new PRRS response pathways that can be targeted for vaccines, drugs and biotherapeutics to prevent and treat PRRSV infections. <P> Obj.3.2. Will use whole genome association studies to reveal new genetic alleles associated with PRRS resistance/susceptibility. The extensive genomic (SNP) analyses will find allele variants that determine resistance/susceptibility of commercial U.S. swine to PRRSV infection.
Approach: Extensive whole-genome association analyses will be performed to determine which markers are associated with PRRS susceptibility/ resistance traits. Simultaneously gene expression analyses are planned to determine PRRS response pathways and critical candidate genes that differ in expression between PRRS resistant versus susceptible PHGC pigs and to dissect pathologic versus protective immune responses in samples collected from PRRSV infected versus vaccinated swine. Overall the proposed studies will identify genetic determinants of resistance/susceptibility of commercial U. S. swine to PRRSV infection. This information will be disseminated to swine breeders, genetics companies and genotyping services so that sets of these recommended genetic markers can be employed in future breeding programs to increase disease resistance.