Evaluation of Different Methods for Conversion of Whole Virion Particle (146S) of FMDV into 12S Subunits and Application in Characterization of Monoclonal Antibodies

Abstract

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven hoofed animals caused by FMD virus classified under genus Apthovirus and Picornaviridae family. Monoclonal antibodies (mAb) to FMDV provides best tool for the development of reliable diagnostics and there is a need for the development of mAbs that specifically recognize either 146S or 12S for the quality control analysis of FMDV vaccines. In the present study, we developed mAbs specific to FMDV serotype O and characterized their specificity in recognition of 146S or 12S particles. Three different methods were evaluated for the conversion of 146S into 12S subunits that includes heat method, strong acid and mild acid methods for testing the reactivity of mAbs with these antigens by double antibody sandwich ELISA. Mild heating of 146S antigens at 560C for 1hour and treatment of 146S antigen with weak acid (0.5M NaH2PO4, pH 4.5 - 5.5) resulted in complete conversion of 146S into 12S. Where as in strong acid method (1N HCl with pH below 4.5), 146S treated with 1N HCl resulted in loss of antigenicity of 12S subunits that reflected in absence of reactivity in ELISA. This may mislead to consider the mAb as 146S specific. This study revealed that mAb binding epitopes of all monoclonals are commonly shared among 146S and 12S antigens. Further it helps in understanding the specificity of mAbs to 146S and 12S particles which will be useful for application of mAbs in different diagnostic assays.