Antigen-Based Diagnosis. The 3AB protein of FMDV was expressed in E. coli [185] [186] [187] or in P. pastoris [188] and has been used for the diagnosis of FMD infection in cattle. Similarly, 3ABC proteins expressed in heterologous systems were used in ELISA (3ABC ELISA) for serodiagnosis of FMD [189, 190] . Further, four serotypes of FMDV structural proteins expressed in P. pastoris and its potential utility either as immunogen or antigen has been successfully assessed in animal model [191] [192] [193] . A recombinant FMDV polyprotein (P1) with 3C expressed in insect cells was evaluated for detecting antibodies to FMDV serotype Asia 1 in ELISA and has the potential to replace the liquid phase blocking (LPB)-ELISA using an inactivated FMDV antigen as a simple and robust serological tool for screening antibodies to FMDV serotype Asia 1 [194] .