While IBDV-mediated immunosuppression is due to the destruction of B cells and the loss of humoral immunity, the clearance of IBDV, and recovery from infection, is known to be aided by bursal T-cell-mediated responses: For example, in one study, Cyclosporin A-induced T cell depletion resulted in an increase in bursal viral load (35), and in another study there was enhanced bursal mRNA transcript levels of cytokines IL-1b, IL-6, CXCLi2, and IFN-γ in IBDV-inoculated birds (38). Here, IL1B is linked to infection.