Multiple Antigenic Peptide (MAP) dendrimer detects Bluetongue virus antibodies with 92.3% sensitivity

Bluetongue disease (BTV) poses a significant global economic threat, particularly to livestock, necessitating advanced diagnostic tools. Current diagnostics often lack the speed, precision, or cost-effectiveness required for widespread surveillance. The Bluetongue virus (BTV) encodes seven structural proteins, with VP7 being a major immunodominant protein conserved across all BTV serotypes. This makes VP7 an ideal target for developing serogroup-specific immunodiagnostic assays, addressing a critical gap in rapid and reliable detection methods.

Researchers aimed to identify an immunodominant VP7 epitope and evaluate its utility in a peptide-based ELISA. They expressed the VP7 gene in three overlapping fragments in a prokaryotic system. Reactivity with two BTV-specific monoclonal antibodies (MAbs) was analyzed via Western blot and indirect ELISA. After identifying the binding domain in Fragment II, linear monomeric peptides failed to show reactivity. To overcome this, a chimeric peptide bridging the junction of Fragments II and III was designed and presented in a four-armed dendrimeric scaffold using Multiple Antigenic Peptide (MAP) technology. This MAP antigen was then evaluated in an indirect ELISA using field serum samples.

Initial epitope mapping successfully identified the binding domain within Fragment II (a 27 kDa region) of the VP7 protein. However, linear monomeric peptides derived from this region failed to replicate the protein's native antigenicity, showing no reactivity with the BTV-specific MAbs. The innovative approach of designing a chimeric peptide presented as a four-armed dendrimeric scaffold using MAP technology proved effective. This MAP antigen successfully restored antigenicity, enabling robust antibody detection. When evaluated with field serum samples, the indirect ELISA based on the MAP antigen demonstrated high diagnostic performance. The assay achieved a diagnostic sensitivity of 92.3% and a diagnostic specificity of 98.2%. These results highlight the successful engineering of a high-affinity peptide construct for BTV antibody detection.

The MAP antigen-based indirect ELISA achieved a diagnostic sensitivity of 92.3% and a diagnostic specificity of 98.2% when evaluated with field serum.