Synthetic peptide vaccine for Foot-and-Mouth Disease: synthesis, characterization and immunogenicity

Background The conjugations of antigenic synthetic peptide sequences with carrier polymers have opened new possibilities for the treatment of diseases. In this study, 135–161 peptide sequence of VP1 capsid protein of Foot-and-Mouth Disease was cross-linked with P(VP- co -AA) copolymer by covalent conjugation using water-soluble carbodiimide at different ratio of components ( γ =5, 7, 9, 11, 15) for the first time in the literature. Materials and methods Bioconjugates were characterized by gel permeation chromatography and fluorescence spectroscopy to identify occurrences of the conjugates. After characterization, γ =15 bioconjugate was determined as optimum conjugate for immunization studies and IC 50 value is calculated as 1.227 mg/mL. By determining the nontoxic range, indirect ELISA were performed to evaluate the immune response elicited in balb/c mice by either peptide or P(VP- co -AA)-peptide bioconjugates ( γ =15). Two injections were applied to each group and high immune responses were obtained against γ =15 conjugate compared to free peptide and control. Results and conclusion At the end of 9-week, the general pattern of immunoreactivity was acquired as γ =15>>peptide>control. Peptide formulated in the conjugated form had higher antibody response than free peptide and control (p<0.01, for all in both cases), this conjugate formulation put forward the adjuvant activity of P(VP- co -AA) polymer.