2011 Annual Report 1a.Objectives (from AD-416) The specific objectives for this agreement are to 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) The University will check for differential gene expression of targeted genes e.g., CD163, SIGLEC1, PTEN, MMP9, IL10, FOXP3, TBET, GATA3, CCL21, MX1, etc., using RT-PCR on PRRS Host Genetics Consortium (PHGC) samples representing different virus/weight categories. This information that will be used in conjunction with analyses collected on the same sample sets at Michigan State University and BARC. For the third objective, the University will help identify and provide samples collected from recent U.S. PRRS infections. 3.Progress Report This agreement documents 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 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. To date, whole blood RNA samples have been prepared by ARS Researchers at Beltsville, MD from several PHGC trials. Pigoligoarray gene expression studies were performed on selected RNA samples from 7 different times post PRRSV infection at Michigan State Univ. (MSU) using 70 arrays. Biostatistical analyses are underway at MSU. At Purdue University scientists will use quantitative PCR analyses to affirm differential gene expression of targeted genes e.g., the PRRSV receptors and critical genes controlling immune anti-viral responses, using RT-PCR. 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. (NP103 2c) This project was monitored through regular email and phone contact, scheduled conference calls, and a yearly Consortium meeting with the participating labs discussing project plans, experimental design, and reviewing data and presentation options.