Development of a Dendrimeric Peptide-Based Approach for the Differentiation of Animals Vaccinated with FlagT4G against Classical Swine Fever from Infected Pigs

Figures

• 

  Figure 1. Peptides used as a coating antigen for ELISA. Serum samples from vaccinated pigs were evaluated either by the FlagDIVA (A), FlagT4G2-NS3 (B), or Flag® (C) ELISA. Red bold letters in peptide B indicate the mutation introduced in the E2 glycoprotein of the FlagT4G vaccine. Box colors indicate the different epitope peptides: blue (original CSFV E2 epitope), green (FlagT4G modified E2 epitope), red (NS3 immunogen), or yellow (commercial 3× Flag). In constructs A and B, thiol-maleimide linkages between the extra C-terminal Cys and both maleimido-derivatized α- and ε- amino ends of the branched Lys core are simplified by wavy lines. Image created using biorender.com (accessed on 22 September 2021).

• 

  Figure 2. Humoral response elicited by the FlagT4G vaccine. (A) Antibodies against the E2 glycoprotein were evaluated by the commercial ELISA (blue shapes and dots); results are expressed as a blocking percentage value (left Y-axis). Antibody detection was also carried out using the FlagDIVA (red shapes and dots) and FlagT4G2-NS3 (tallow shape and dots) dendrimeric peptides and is expressed as an O.D. value (right Y-axis). For both assays, values corresponding to negative samples are shown in the shaded area below the horizontal dotted line (40% blocking percentage for the commercial ELISA and 0.4 O.D. for the dendrimeric peptide tests). Lines within the boxes indicate the mean value for each assay. (B) Humoral response detected by the Flag® peptide. Sera from the vaccinated animals was evaluated at different timepoints after vaccination; results are expressed as an O.D. value. Mean values (line within the box) are shown for each timepoint.

• 

  Figure 3. Detection of antibodies against CSFV by the FlagDIVA dendrimeric peptide. (A) Serum samples from naïve pigs (blue triangles) as well as animals infected with CSFV strains of different genotypes (red triangles) were evaluated by the FlagDIVA and commercial ELISA tests. Results are shown in comparison with qualitative results from the commercial assay (X-axis). (B) Samples from CSFV-infected animals that were either negative (green triangles), doubtful (orange triangles), or positive (gray triangles) by the commercial ELISA were subsequently compared to their results in the FlagDIVA assay according to their time after infection (X-axis). Quantitative results for the FlagDIVA assay are shown as an O.D. value (Y-axis) in both panels, with their respective threshold (dotted line).