1a.Objectives (from AD-416)
The specific objectives of this agreement includes Identify differentially expressed (DE) genes in blood in response to PRRSV infection. Determine putative gene sets and pathways that predict a pig's ability to clear PRRSV infection and maintain weight gain; and Validate utility of gene sets and pathways for prediction of responsiveness to PRRSV infections in multiple populations. Predictive blood tests of pigs with improved PRRS disease resistance and growth maintenance; increased understanding of mechanisms involved in pig responses to PRRSV infection; scientific publications.
1b.Approach (from AD-416)
Michigan State University (MSU) researchers will contribute to the first two objective through developing statistical methods for selecting samples for evaluation from Tempus tube preserved blood samples collected through the PRRS Host Genetics Consortium (PHGC) representing pigs in different virus/weight categories. Perform all the microarray work and transcriptional profiling for the first two objectives and analyze all microarray data (processing and normalization and use of statistical programs to identify DE genes). MSU researchers will also collaborate on planning analysis of DE gene QPCR data (generated by USDA ARS BARC) for all Objectives.
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) 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 by ARS Researchers at Beltsville, MD from PHGC trial 1-4 for planned Pigoligoarray gene expression studies that will start in fall 2010 at MSU. 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.
Disseminating progress on this grant was through regular email and phone contact, scheduled conference calls and yearly Consortium meeting with the participating labs discussing project plans, experimental design and reviewing data and presentation options.