Location: Animal Parasitic Diseases Laboratory2010 Annual Report
1a. Objectives (from AD-416)
The specific objectives will be 1) Identify differentially expressed (DE) genes in blood in response to PRRSV infection; 2) Determine putative gene sets and pathways that predict a pig’s ability to clear PRRSV infection and maintain weight gain; and 3) Validate utility of gene sets and pathways for prediction of responsiveness to PRRSV infections in multiple populations.
1b. Approach (from AD-416)
The proposed studies will identify functional genomic determinants, and potential “classifier genes” that predict resistance/susceptibility of commercial U.S. swine to PRRSV infection and associated growth losses. Such gene-specific information will directly complement the genetic variation and QTL mapping data being developed in the PHGC, to provide an integrated view of the molecular genetic architecture of PRRSV resistance. All information will be disseminated to swine researchers and breeders, as well as genetics companies and genotyping services so that these recommended genes can be targeted in future breeding programs to increase resistance to PRRS, the most economically important disease affecting the U.S. pork industry.
3. Progress Report
A new project was established to perform functional genomic analyses to determine response pathways that differ in porcine respiratory and the reproductive syndrome (PRRS) resistant versus susceptible PRRS Host Genetics Consortium (PHGC) pigs. ARS Researchers at Beltsville, MD have partnered with Michigan State University (MSU), Iowa State University (ISU), Washington State University and Purdue University scientists to use PHGC samples to assess whole blood gene expression responses to identify genes and pathways that are associated with pigs that clear PRRS virus (PRRSV) and that grow well despite PRRSV infection. With MSU scientists multivariate statistical analyses of viral load and weight data have categorized PHGC pigs into 4 extreme categories including the most desirable, PRRS resistant low virus/high weight gain pigs, the worst, PRRS susceptible high virus/ low weight gain pigs, the PRRS tolerant, high virus/high weight gain pigs, and the less thrifty, low virus/low weight gain pigs. This statistical categorization of pigs from each PHGC trial provides a critical basis for selecting pigs and samples for detailed analyses of processes that control transcriptional and proteomic responses to PRRSV infection. To date, RNA samples have been prepared ARS Researchers at Beltsville, MD from PHGC trial 1-4 for planned Pigoligoarray gene expression studies. As this work progresses we expect to develop predictive gene expression pathways and classifier genes that identify pigs which resist PRRSV infection and grow normally.