A multi-species indirect ELISA for detection group-specific antibodies against VP7 protein of bluetongue virus

In the present study, a multispecies indirect ELISA for the detection of serogroup-specific antibodies against the VP7 protein of bluetongue virus (BTV) has been developed. The assay was optimized using a peroxidase-conjugated protein G secondary antibody that can detect antibodies from multiple species. Serum samples (n = 515) from small and large domestic ruminants were used to optimize the assay. The percent positivity (PP) values were used for the estimation of cut-off values. On receiver operator characteristic (ROC) analysis, different cutoff values along with their diagnostic sensitivity (DSn) and diagnostic specificity (DSp) were obtained. Among these, > 20.24% PP value was accepted as the cut-off at which DSn was 96.05% with 92.9-98.1 (95%) confidence interval and DSp was 98.47 with 96.1-99.6 (95%) confidence interval. The above results indicate that the multispecies i-ELISA assay is sensitive, specific and minimize the dependence of species-specific conjugated antibodies for serological investigation of bluetongue in small and large ruminants.