Recently, we have developed a novel
vaccine for
Bluetongue named BT Disabled Infectious Single Animal (DISA)
vaccine. Due to the lack of non-essential NS3/NS3a
protein, BT DISA
vaccine is a replicating
vaccine, but without the inherent risks of live-
attenuated vaccines, such as residual virulence or reversion to virulence by mutations, reassortment with field virus, horizontal spread by vectors and vertical transmission. The immune response induced by BT DISA
vaccines is rapidly induced, highly protective and serotype specific which is dependent on the immunodominant and serotype determining VP2
protein. The BT DISA
vaccine platform provides the replacement of exclusively VP2 from different serotypes in order to safely formulate multivalent cocktail
vaccines. The lack of NS3/NS3a directed
antibodies by BT DISA vaccination enables differentiation of infected from vaccinated animals (DIVA principle). A highly conserved immunogenic site corresponding to the late domain was mapped in the N-terminal region of NS3. We here established an NS3-specific competitive ELISA (NS3 cELISA) as serological DIVA test accompanying BT DISA
vaccines. To this end, NS3
protein missing putative transmembrane regions was produced in large amounts in bacteria and used as
antigen in the NS3 cELISA which was investigated with a variety of sera. The NS3 cELISA displayed a high sensitivity and specificity similar to the commercially available VP7-specific cELISA. Results of previously performed vaccination-challenge trials with BT DISA
vaccines clearly demonstrate the DIVA system based on the NS3 cELISA and BT
vaccine free of NS3
protein.