RECOMBINANT APHTHOVIRUS CHIMERA OF THE GLYCOPROTEIN OF VESICULAR STOMATITIS VIRUS EVALUATED AS DNA AND PROTEIN-BASED VACCINES IN MICE AND CATTLE

A. CAPOZZO; J.L. LA TORRE, D. BUCAFUSCO, O. FRANCO MAHECHA, D.M. PÉREZ FILGUEIRA Y P. GRIGERA

Viena

Otro; OPEN SESSION OF THE EuFMD STANDING TECHNICAL COMMITTEE; 2010

FAO

Introduction A chimeric antigen was developed observing the rationale of circumventing the major constraints in the development of epitope-based recombinant vaccines: difficulties to retain the native conformation of key-neutralizing antibody epitopes, the need for effective but safe adjuvants and the complexity to stimulate effective T-lymphocyte responses, particularly in cattle, due to the bovine major histocompatibility complex molecules´ polymorphism. Materials and Methods Chimeric genes were engineered inserting an in tandem-dimer of the antigenic site A (ASA) of the VP1 capsid protein of the foot-and-mouth disease virus C3 serotype (FMDV C3, aa 139-149) into codons 160 and 161 of the Vesicular Stomatitis Virus New Jersey serotype (VSV-NJ) glycoprotein (G) gene cDNA. The sequence was cloned in pCDNA and expression assessed in vitro. This carrier protein allowed ASA to be exposed as to mimic a number of conformations present on the surface of native FMDV particles, able to raise and react with neutralizing antibodies, while VSV-G provided bovine-effective T cell epitopes. Results DNA vaccines and Baculovirus-expressed recombinant chimera were evaluated in mouse and calves. Antibodies induced by these vaccines recognized ASA in the native conformation displayed by whole-native FMDV particles. Humoral neutralizing responses were induced in both animal models, though kinetics and quality of the specific IgG were different. Plasmidic DNA performed better in calves than in adult mice. DNA vaccination elicited specific IgG1 at 15 dpv in calves while immune responses to DNA vaccines in mice were delayed respect to their protein counterpart. Protein and DNA vaccinated calves elicited high levels of specific antibodies reaching an expectative of protection above 80% as determined by Liquid Phase Blocking ELISA. Discussion These results show that combining correct display of epitopes that bind conformational-dependent-neutralizing antibodies with aligned bovine T cell epitopes can circumvent immunological limitations in the development of recombinant peptide-based vaccines.