Development Of Synthetic Peptide Vaccine For Food-and-Mouth Virus Type Asia I

Conventional inactivated FMD vaccines have been used for many years but have their disadvantages. Recent epidemics of severe FMD epidemic highlight the urgency for developing new generation vaccine. FMDV exists as seven distinct serotypes and each serotype shows a spectrum of intra-typic antigenic diversity. FMDV exhibits high mutation rates even in the absence of immune selection, leading to amino acid-related antigenic variation. FMDV has a genome encoding encoding4viral structural proteins, VP1, VP2, VP3and VP4as well as8non-structural proteins namely2A,2B,2C,3A,3B,3C and3D. Variations in the amino acid sequence between each serotype structural proteins were demonstrated mainly in VP1, followed by VP3and VP2. The amino acids insertions or depletions around the RGD arginine-glycine-aspartate (RGD) motif account for the different length of VPls. Several studies demonstrated the diverse function of VP1G-H loop including immune stimulating and integrin binding mediated by RGD. In epitope vaccine studies, peptides contains the RGD motif were used for immunizing animals and revealed that immune effectiveness are affected by sequences flanked RGD. In this study, the peptide between amino acid129and169within VP1was selected as epitope.Previous studies demonstrated that the protective immune response against FMDV is T cell-Independent, which was evidenced by the fact that synthetic peptide contained T cell epitope could enhance immune responses. Peptide located in NSP3D346-370contains an epitope which is recognized by swine T cells without restriction by MHC. As universal T cell epitopes such as PADRE are generally utilized for enhancing immune effectiveness, the afomentioned two epitopes were selected for preparing synthetic peptide vaccine in this study.In the present study,3combined peptide P1:(Ac-VP1134-159)4-KKK-3D346-370-KK, P2Ac-3D346-370-GG-VP1129-169(134(T→C),(RGD→RDD),155(N→D),156(R→C)) P3Ac-PADRE-GG-W1129-169(134(T→C),(HGD→RDD),156(R→C)) were synthesized and used as antigens for immunizing guinea pigs, with inactivated vaccine and PBS controls. Cell mediated immunity was evaluated according to the IgG, IgGl, IgG2a titers, cytokines expression profiles and splenic lymphocyte cytokines ELIspot. The immunized guinea pigs was challenged with FMDV at42dpi. Results demonstrated that peptide P1displayed100%proetection. Comparatively, peptide P2showed no protection and P3displayed50%protection.The results provide the reliable basis for the more development of FMDV Asia I synthetic peptide vaccines.