Location: Animal Parasitic Diseases LaboratoryTitle: Distinguishing fetal and placental immune responses to congenital infection with porcine respiratory and reproductive syndrome virus using NanoString arrays
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/18/2019
Publication Date: N/A
Technical Abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) infections cause major reproductive losses, with an estimate of over $300 million annual losses in the U. S. alone. Joint studies of ARS scientists at Beltsville, Maryland, with scientists at the University of Saskatchewan, have probed responses to PRRSV infection in third-trimester pregnant gilts, and assessed maternal and fetal factors that could be predictive of PRRS severity and resilience in fetal pigs. The expression of immune-related genes in fetuses with no, low or high viral load at 5 to 12 days post maternal PRRSV infection was investigated. Differential expression (DE) of genes was evaluated using a 230 gene NanoString array (designed on biomarkers previously predicted to alter PRRS resistance and susceptibility). Based on log viral load PLC and fetal thymus (THY) samples were assigned to 3 experimental groups: ND (none detected), LOW and HI viral load. The resulting data were normalized, and a univariate analysis conducted using a Generalized Least Squares (GLS) model with false discovery rate (FDR) correction. In the PLC a total of 52 genes were found to be significantly upregulated between ND and HI. In the THY a total of 197 and 84 genes were found to be differentially expressed between ND-LOW and ND-HI, respectively. 35 genes were found to be commonly DE for PLC and THY, with response to type 1 interferons (IFNs) including upregulation of STAT1-3 and IFN response genes (IFIT1-3, IFIHI, IRF1&5 and GBP). Efforts are continuing to assess the impact of viral load in PLC and thymuses to distinguish the effect of viral infection and cross placental transmission on fetal survival and local immune responses. These studies have affirmed the diversity of fetal pig anti-PRRSV response within each litter and have set the stage for more detailed analyses now underway to probe for key markers of fetal pig PRRS resilience.