Abstract / Description
Spotty Liver Disease (SLD) is an acute bacterial infection of layer chickens in production, caused by Campylobacter hepaticus, and occurs most frequently in barn-housed and free-range systems. The disease is characterized by a sharp decline in egg production and increased mortality. The hallmark pathological feature is 1-2 mm white to grey necrotic foci distributed across the liver surface. Despite its growing economic impact on commercial poultry, the molecular mechanisms underlying host responses to C. hepaticus infection remain poorly understood. To address this gap, we performed a comprehensive transcriptome analysis of liver tissue from chickens naturally infected with SLD compared to uninfected controls. Illumina NovaSeq-based RNA sequencing was performed on liver tissues collected from three SLD-infected and three uninfected control chickens, with three biological samples for each sample type (n = 6), yielding 9,277 differentially expressed genes (DEGs), of which 3,063 were upregulated and 6,214 were downregulated. Functional pathway enrichment analysis revealed significant alterations in immune and metabolic processes associated with SLD pathophysiology. Infected chickens exhibited significant activation of immune response pathways, particularly cytokine-cytokine receptor interactions involving interleukins IL-22, IL-21, and IL-6, along with enhanced cell signaling, and cell adhesion. Among the individual genes, C1QTNF1 and the adhesion molecule gene ADGRD1 were notably overexpressed, indicating enhanced inflammatory activity. In contrast, core hepatic metabolic functions were profoundly reduced (adjusted p