Evaluation of Adjuvanticity and Protective Efficacy of Recombinant ORFV B2L Protein Adjuvanted FMD Vaccine in Guinea Pigs

The present study evaluates the adjuvant effect of rec-B2L protein of orf virus and widely used oil adjuvant with purified inactivated FMDV 146S trivalent antigens (O, A and Asia 1) in guinea pig model. Rec-B2L protein expressed in prokaryotic expression system was co-administered intradermally with FMDV trivalent antigens. The serum antibody titre, CMI response and protective efficacy against FMDV-type ‘O’ virulent virus challenge were assessed. The antibody titres of oil adjuvant group were found highest. However, rec-B2L group showed better antibody titre than the control group. The levels of IgG1 were found to be constant throughout the experiment except some fluctuations noticed on 14th and 28th dpv against serotype A and Asia1. Rec-B2L group showed higher levels of IgG2 against serotype A on 14th and 28th dpv than FMDV trivalent antigens alone. Further, the adjuvant effect of rec-B2L protein was also reflected by enhanced levels of IFN-γ, TNF-β on 28th dpv; IL-15, IL-10 on 7 dpv in the immunized serum samples. The oil adjuvant group and rec-B2L group showed a centum protection following challenge on 28th dpv. These preliminary findings indicate the adjuvant effect of rec-B2L protein.