Immunogenicity of Foot-and-Mouth Disease Virus Dendrimer Peptides: Need for a T-Cell Epitope and Ability to Elicit Heterotypic Responses

Figure 1. Incorporation of both B- and T-cell epitopes is required for efficient induction of FMDV-specific antibodies by FMDV dendrimers. Antibodies in sera from groups of animals (n = 10 Swiss mice) immunized twice (on days 0 and 20) with 0.1 mg/dose of B2T-3A, B2+T-3A, B2 or T-3A. ELISA titers against B2 peptide at 20 days pi (A) and 42 days pi (B). Virus-neutralizing antibody titers (VNT) on day 42 pi against O/UK/11/2001, a type O FMDV isolate whose sequence is homologous to those of the B2 and T-3A peptides (C). Each point represents the mean of a triplicate assay for each mouse. Dotted lines indicate the detection limit of the assay. Values are expressed as the reciprocal log10 of the serum dilution that neutralized 100 TCID50 of FMDV. Statistically significant differences are indicated by asterisks (*) for p < 0.05, (**) for p < 0.01, (***) for p < 0.001, (****) for p < 0.0001, and (*****) for p < 0.00001.

Figure 2. The mixture of two heterotypic B2T-3A constructs elicited similar levels of neutralizing antibodies against Type C and Type O FMDVs. Neutralizing antibody titers in sera samples on day 40 pi from mice immunized twice (on days 0 and 21) with an equimolar mixture of B2T-3A-O + B2T-3A-C or with B2T-3A-C or B2T-3A-O against Type O FMDV (O/UK/11/2001 isolate) (A) and Type C FMDV (C-S8 isolate) (B). (C) To measure the relationship between antibody titers to serotypes C and O in each animal, Pearson’s correlation coefficient (r) was calculated: r = 0.07. Each point represents the mean of a triplicate assay of each animal (n = 8). Values are expressed as the reciprocal log10 of the serum dilution that neutralized 100 TCID50 of each FMDV.