BAFF enhances B-cell-mediated immune response and vaccine-protection against a very virulent IBDV in chickens

Infectious bursal disease (IBD) is an acute, highly infectious and immunosuppressive disease caused by IBDV, which specifically targets destruction of B cells in the bursa of Fabricius. B-cell activating factor belonging to the TNF family (BAFF, also called BLyS, TALL-1, THANK, or zTNF4) is an important factor for B-cell proliferation and survival. Here we demonstrate that human soluble BAFF (hsBAFF) may enhance humoral immune response by elevating B lymphocyte activity of secretion of immunoglobulin (Ig) such as IgA, IgM and IgG in chickens immunized or unimmunized with an inactivated IBDV vaccine from a very virulent strain. Of importance, we found that hsBAFF, as a co-immunostimulant for vaccination, may play a vital role in amplifying the specific protective immune response, thereby potently preventing very virulent IBDV challenge. This is supported by serological evidence that hsBAFF may effectively enhance higher specific IgG activity and titre in serum of immunized chickens. The findings strongly suggest that BAFF may be exploited in combination with specific vaccination for prevention of IBD.