Transcriptomic Signatures of Chicken DF-1 Cells Following Toll-Like Receptor 3 Stimulation

Prophylactic agents and adjuvants induce immune responses against pathogens in animals, including chickens. Polyinosinic-polycytidylic acid (PIC), one of the prophylactic agents and a TLR3 agonist, mimics double-stranded viral RNA and triggers antiviral immune responses. This study employed RNA sequencing to analyze the transcriptional profile of DF-1 cells stimulated with PIC. Among 16,550 transcripts, 376 differentially expressed genes (DEGs) were identified, with 279 (74.2%) upregulated and 97 (25.8%) downregulated. Notably, PIC significantly increased the expression of inflammatory genes, particularly Interleukin 8-like 1 (IL8L1) (9.5-fold change), while downregulating Mitogen-activated protein kinase kinase 6 (MAP2K6). Gene Ontology analysis revealed enrichment of immune-related biological process (BP) terms, and REACTOME analysis highlighted significantly enriched pathways, including cytokine signaling in the immune system and regulation of the ERK1/2 and MAPK cascades. Dual-specificity phosphatases (DUSPs) and sprouty proteins (SPRYs), key regulators of ERK1/2 and MAPK signaling pathways, showed distinct upregulation upon PIC treatment, as confirmed by quantitative RT-PCR (qRT-PCR). Additionally, ERK and MAPK were upregulated in samples infected with Avian Influenza Virus (AIV), suggesting similarities in signaling pathways involved in viral immunity. These findings underscore the potential role of ERK1/2 and MAPK signaling pathways in mediating innate immune responses to PIC treatment and AIV infection, with DUSPs and SPRYs likely playing regulatory roles in these pathways. This study provides insight that could inform the development of antiviral and anticancer therapies.