Effective protection by high efficiency bicistronic DNA vaccine against infectious bursal disease virus expressing VP2 protein and chicken IL-2

Infectious bursal disease (IBD) is an acute and contagious viral infection of young chickens caused by IBD virus (IBDV). IBDV belongs to genus Avibirnavirus of family Birnaviridae. It is a non-enveloped virus with icosahedral symmetry that contains two segments of double-stranded RNA. The virus affects the lymphoid tissues of chickens, mainly the B cells of bursa of Fabricius, leading to severe and prolonged immunosuppression. VP2. a major structural protein of IBDV, contains antigenic epitopes responsible for induction of neutralizing/protective antibody. In the present study, VP2 gene of IBDV was cloned in a bicistronic vector along with chicken interleukin-2 (chilL-2) as an adjuvant. An in vivo challenge study of bicistronic DNA vaccine expressing IBDV-VP2 and chicken IL-2 showed effective protection against a lethal IBD infection in chickens. In addition, mortality, gross picture of bursa and histopathological findings demonstrated the efficacy of the vaccine in reducing virulence of the disease. (C) 2008 Elsevier Ltd. All rights reserved.