Effect of Circulating Calcitriol (1,25(OH)2D3) Levels on Th1/Th2 Immune Response in Bovine Ephemeral Fever

This study aimed to investigate the changes in Th1, Th2, and Th17 cytokine levels resulting from inflammation in cattle naturally infected with bovine ephemeral fever (BEF) and to explore the relationship between these changes and vitamin D and its metabolites. The study sampled 28 BEF positive cattle, whose samples were diagnosed by polymerase chain reaction (PCR), and 15 healthy cattle as a control group. The BEF group had significantly lower serum 1,25(OH)(2)D-3 levels than the control group (P=0.000) whereas there was no significant difference between the two groups in 25(OH)D3levels (P=0.063). Among the serum cytokines, IL-2 and IL-4 were increased in the BEF group compared to the control (P=0.005, P=0.001). While IL-10 and IL-17 levels were higher in the BEF group than the control group (P=0.000), there was no significant difference between the two groups in IFN-gamma levels (P=0.083). BEF group had lower total protein (TP), calcium (Ca) and phosphorus (P) levels (P=0.000, P=0.000, and P=0.002 respectively). In addition, the percentage increases in cytokines in cattle with BEF were determined as IL-17 (37.78%), IL-10 (27.00%), IL-4 (16.66%), IL-2 (15.01%) and IFN-gamma (2.93%), respectively. These findings indicate that the Th1 response is partially suppressed, whereas the Th2 and Th17 responses are significantly increased in cattle infected with BEF. In addition, it was determined that extrarenal 1,25(OH)(2)D-3 synthesis was decreased in cattle infected with bovine ephemeral fever virus (BEFV). This suggests that the BEFV suppresses 1,25(OH)(2)D-3 synthesis and causes dysfunction in the steps within the immune system involved in immune response.