Cell-mediated immune response and cross-protective efficacy of binary ethylenimine-inactivated bluetongue virus serotype-1 vaccine in sheep

Bluetongue is a serious hemorrhagic disease of sheep, cattle and other ruminants causing economic losses worldwide. Recent invasion of multiple bluetongue virus serotypes (BTV) in various countries warrants immediate development of efficacious vaccine that targets more than one serotype. In the present study, the cross-protective efficacy of binary ethylenimine (BEI)-inactivated BTV-1 vaccine was evaluated in Indian native sheep against virulent heterologous BTV-23 serotype challenge. BTV-1 vaccination induced significant cell-mediated immunity (CMI) as determined by lymphoproliferative responses, and increased CD8 T cell, IL-2 and IFN-γ responses. Both naïve and immunized sheep also showed increased CD4 T cell, IL-12 and IFN-α responses. Collectively, these data suggested that inactivated BTV-1 vaccine induced appreciable CMI and greatly reduced the severity of heterologous BTV-23 infection.