Vaccine 27 (2009) 1393–1399 Contents lists available at ScienceDirect Vaccine journal homepage: www.elsevier.com/locate/vaccine BAFF enhances B-cell-mediated immune response and vaccine-protection against a very virulent IBDV in chickens Long Chen a,b,∗,1 , Mao Ju Ran c,1 , Xiao Xiao Shan a , Meng Cao a , Peng Cao a , Xiao Man Yang a,b , Shuang Quan Zhang a,∗,2 a College of Life Sciences, Nanjing Normal University, and Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, Nanjing 210046, PR China b Jiangsu Engineering Research Center for Biomedical Function Materials, Nanjing 210097, PR China c Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, PR China article info Article history: Received 27 October 2008 Received in revised form 13 December 2008 Accepted 20 December 2008 Available online 13 January 2009 Keywords: BAFF Chicken IBDV Vaccine abstract 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. © 2009 Elsevier Ltd. All rights reserved. 1. Introduction Infectious bursal disease (IBD), caused by infectious bursal dis- ease virus (IBDV), is an acute and highly contagious disease in chickens 3 weeks of age and older [1,2]. It elicits high mortality in infected chickens and induces immunosuppression in recovered chickens. The immunosuppression contributes to an important eco- nomic impact to the poultry industry worldwide [2]. The principle target for IBDV replication is the bursa of Fabricius and especially B lymphocytes [3,4], leading to severe lesions in the bursa of Fabricius, such as inflammation, hemorrhage, lymphocytolysis and atrophy [5], and destruction of B cells [6]. Therefore, IBDV-challenged chick- ens show severe suppression in humoral immunity. Many data have reported that principal method for preven- tion of IBD, like for other viral diseases of chicken is effective vaccination against IBD, including vaccination of chickens with ∗ Corresponding authors at: College of Life Sciences, Nanjing Normal Univer- sity, and Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, Nanjing 210046, PR China. Tel.: +86 25 85891797; fax: +86 25 85891526. E-mail addresses: lchen@njnu.edu.cn (L. Chen), zhangshuangquan@njnu.edu.cn (S.Q. Zhang). 1 These authors contributed equally to this work. 2 Tel.: +86 25 85891053. inactivated oil-emulsified vaccines or birds by live attenuated vac- cines [1,2,6]. Inactivated vaccines are typically safe but less effective than attenuated vaccines [2]. However, some chickens immunized with live attenuated IBD vaccines showed a certain degree of bur- sal atrophy and immunosuppression that interfered with other vaccinations and especially, after the emergence of virulent IBD, mild vaccines are generally ineffective [7–9]. Because of these several disadvantages, new more effective vaccination methods need to be developed to amplify the specific protective immune response. The TNF family ligand B-cell-activating factor belonging to TNF family (BAFF), also known as BLyS, TALL-1, THANK, zTNF4 or TNFSF13b, is synthesized as a 285-amino acid type II trans- membrane protein and exists in both membrane and cleaved 152-amino acid soluble forms [10–13]. Both forms of BAFF have similar functions. In mammals, BAFF is mainly produced by macrophages/monocytes, dendritic cells (DCs), and T lymphocytes [10,14–16], whereas chicken BAFF (chBAFF) is primarily produced by B cells both in peripheral lymphoid organs and in the bursa of Fabricius, the chicken’s unique primary lymphoid organ [17–20]. Interestingly, the amino acid identity between soluble chicken and human BAFF is 76%, considerably higher than for most other known cytokines [17]. Koskela et al. revealed that recombinant human BAFF (hBAFF) has a positive effect on bursal B-cell prolifer- ation, and transiently inhibits cell death in vitro [18]. Accumulated 0264-410X/$ – see front matter © 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2008.12.040