Transcriptome analysis of pig macrophages expressing porcine reproductive and respiratory syndrome virus non-structural protein 1

Porcine reproductive and respiratory syndrome virus (PRRSV) is a causative pathogen of PRRS, one of the most economically disastrous swine diseases. Non-structural protein 1 (NSP1) of PRRSV consists of NSP1α and NSP1β which exhibit papain like cysteine protease activity. Recent evidence demonstrates that PRRSV NSP1 may be participated in modulating host immunity, but very few host proteins were discovered as targets for NSP1. In this study, we used RNA-seq to investigate the functional role of PRRSV NSP1 in porcine alveolar macrophages, 3D4/31 cells. Compared to empty vector (mock) transfectant, NSP1, NSP1α, and NSP1β expressing 3D4/31 cells displayed a total of 60 genes, 63 genes, and 80 genes as differentially expressed genes (DEGs), respectively. Most of DEGs are involved in early inflammatory responses including interleukin (IL)-17 signaling pathway, chemokine signaling pathway, tumor necrosis factor (TNF)-α signaling pathway, and cell adhesion molecules. Interestingly, PRRSV NSP1 expression in 3D4/31 cells decreased mRNA transcripts of Fosb and Gdf15 known to be involved in host cell signaling or host cell protection during inflammation. Therefore, PRRSV NSP1 might block the signaling involved in host immune surveillance. Further study is required to define the mechanism on how PRRSV NSP1 protein represses mRNA transcripts of specific host genes.