Application of a recombinant capsid polyprotein (P1) expressed in a prokaryotic system to detect antibodies against foot-and-mouth disease virus serotype O.

Foot-and-mouth disease (FMD) is a highly contagious epidemic disease of transboundary importance. In India, the disease is endemic in nature and is controlled primarily by prophylactic bi-annual mass vaccination. In this control programme, liquid-phase blocking ELISA (LPBE) is being used widely for post vaccination seromonitoring. In order to develop an alternative assay to LPBE, the recombinant capsid polyprotein (rP1) of FMD virus (FMDV) serotype O was expressed in Escherichia coli and used as an antigen for the detection of antibodies to FMDV. The capsid polyprotein of FMDV serotype O could be expressed successfully as a recombinant 6xHis-SUMO tagged protein in soluble form. In a Western blot assay, the rP1 protein reacted strongly with anti-FMDV serotype O guinea pig and bovine serum. Further, in this study, an rP1 protein-based solid phase competitive ELISA (rP1-SPCE) was developed and evaluated with a set of serum samples representing the various epidemiological situation of the country. The performance of the rP1-SPCE was compared with the in-house LPBE, and overall, an excellent agreement (kappa = 0.95) was observed between the two tests. This report demonstrates that the recombinant capsid polyprotein-based ELISA has the potential to be an easy-to-perform, safe alternative to the conventional LPBE for the quantitative detection of antibodies to FMDV serotype O.