Techniques developed in China for foot-and-mouth disease diagnosis.

Over the past several decades, a series of new methods have been developed in China for the diagnosis of foot-and-mouth disease (FMD). These methods are theoretically consistent with Office International des Epizooties standards for FMD diagnosis and include: antigen-capture ELISA and colloid-gold test strip for viral antigen typing, liquid-phase blocking ELISA (LPBE) for detection of antibodies against O and Asia 1 FMDV, and an indirect ELISA for detection of antibodies against the non-structural protein (NSP) 3ABC (3ABC-I-ELISA). Several molecular diagnostic methods have also been developed for detection of fragments of the FMDV genome within viral samples, such as multiplex RT-PCR, typing RT-PCR and real-time RT-PCR. In China, FMD vaccines are compulsorily used in all livestock. In such a situation, monitoring of the immune status of animal herds and disease surveillance become very important. Liquid-phase blocking ELISA is routinely used in China for monitoring the immune status, and 3ABC-I-ELISA is feasible for large-scale serological surveys based on differentiation of FMDV-infected animals from vaccinated animals. Combined use of 3ABC-ELISA and mRT-PCR is described for survey of FMD virus-prevalent herds and virus carriers.