1a.Objectives (from AD-416):
The specific objectives of this agreement include 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):
Washington State University (WSU) will contribute to the first and third objectives. The first objective WSU will search public databases and use bioinformatic tools to examine the transcriptome of alveolar macrophages in response to PRRSV infection. This data will serve as a reference to determine what genes are expressed exclusively or predominantly in response to PRRS infection and compared to Michigan State University full transcriptome data. For the third objective, WSU will annotate specific porcine genes manually using comparative annotation procedures for retrieval of both cDNA and genomic DNA sequences of each gene identified in the second objective. WSU will then detect putative splicing forms in each of selected DE pig genes using three approaches – comparative analysis in mammals, EST evidence and PCR screening. The different sizes of products will be sequenced and the tentative splicing forms examined. Primers will be designed to target different splicing form and RT-PCR carried out to examine which form is most abundantly expressed in high or low responders to PRRSV infection.
By comparing anti-viral responses of resistant versus susceptible pigs we are we are attempting to identify biomarkers expressed by pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV), a major swine pathogen which causes $664 million per year losses to the U.S. pig industry. ARS scientists at the Beltsville Agricultural Research Center (BARC) in Beltsville, Maryland have partnered with Washington State University (WSU) scientists to use PRRS Host Genetics Consortium (PHGC) samples to identify genes and pathways expressed at different levels in resistant versus susceptible pigs. At WSU comparative bioinformatic tools are being used to probe for specific pig genes and their size variants that might identify important innate immune pathways active early after PRRSV infection. Future work will validate, with specific assays, which of these genes and pathways are consistently over- or under-expressed in pigs that exhibit greater resistance to this important virus.