Development of Nanostring Codesets to Evaluate Fetal and Maternal Gene Expression in Response to Porcine Reproductive Reproductive and Respiratory Syndrome Virus (PRRSV) Infection

Porcine Reproductive and Respiratory Syndrome virus (PRRSV) infection causes reproductive failure in pregnant females with abortions, fetal death, and weak born piglets. We used a pregnant gilt model (PGM) to probe the mechanisms of PRRSV-induced reproductive failure. PGM1 tested effects at 21 days post infection (dpi) in pregnant gilts inoculated at 85 day gestation (DG). PGM2 used 85 DG gilts that were controls (n=5) or type 2 PRRSV inoculated (n=15). Gilts were euthanized at 2, 5, 8, 12, and 14 dpi, fetal preservation status evaluated and blood and tissue samples collected to measure viral load and assess when the virus crosses the maternal fetal interface (MFI) and infects the fetuses. For each fetus, the thymus was collected as well as maternal endometrium and fetal placenta. Our goal is to characterize factors regulating the effects of PRRSV movement across the MFI and mechanisms of PRRSV pathogenesis. We will analyze gene expression using NanoString technology by comparing data from fetal tissues from negative control gilts (NEG) and each of 3 PRRSV inoculated gilts [matching littermates - PRRSV negative, uninfected (UNINF) with infected (INF)] based on fetal serum and thymus PRRSV viral load. For Nanostring codesets, 240 genes were selected for expression analyses based on data from past PRRSV infection studies. Critical gene sets and pathways that were significantly associated with post-PRRSV infection responses included signaling pathways associated with IFNs, TREM1, HMGB1, BCR/TCR, TLR, and apoptosis/mitosis and genes related to endometrium and placenta tissue remodeling and epithelial integrity. Overall this data should reveal mechanisms involved in PRRSV transmission from the gilt to some, but not all, of her fetuses and highlight genes which predict prevention of in utero fetal PRRSV infection. Funding provided by Genome Canada, Genome Prairie, Chinese Scholarship Council fellowship, and USDA ARS.