CONICET | Buscador de Institutos y Recursos Humanos

Epitope-based vaccine design has been studied as alternatives to the current Foot and Mouth Disease Virus (FMDV) inactivated vaccine. However most of the neutralizing-protective antibodies are directed to the antigenic site A (ASA), the major epitope on the VP1 capsid protein (aa 139-149, FMDV-C3 serotype), which has conformational flexibility on the viral particle, which must be resembled by the peptide to induce neutralizing antibodies. To overcome this limitation and add ubiquous Tcell epitopes, we developed a chimeric antigen using Vesicular Stomatitis Virus Glycoprotein (VSV-G) as carrier of an in tandem-dimer of ASA This particular design exposes one ASA motif in the peptide surface. The G-ASA construct was expressed in the Baculovirus system to produce a recombinant protein (DEL BAC) (cloned in pCDNA 3.1 plasmid) (Invitrogen Corporation, Carlsbad, CA) and was also prepared as a DNA vaccine (pC DEL). Calves vaccinated with both immunogens elicited antibodies that recognized the ASA in whole virion and were able to neutralize FMDV infectivity in vitro. After two vaccine doses, DEL BAC induced serum neutralizing titers compatible with an ??expected percentage of protection?? above 90%. Plasmid pC DEL stimulated FMDV specific humoral responses earlier than DEL BAC, though IgG1 to IgG2 ratios were lower than those induced by both DEL BAC and inactivated FMDV-C3 after the second dose. DEL BAC induced FMDV-specific secretion of IFN-c in peripheral blood mononuclear cells of outbred cattle immunized with commercial FMDV vaccine, suggesting its capacity to recall anamnestic responses mediated by functional T cell epitopes. The results show that exposing FMDV-VP1 major neutralizing antigenic site in the context of N-terminal sequences of the VSV G protein can overcome the immunological limitations of FMDV-VP1 peptides as effective protein and DNA vaccines for cattle.