[Google Scholar] 6. rates. In this study, a multiepitope-based indirect chemiluminescence immunoassay (ME-CLIA) was developed for specifically detecting antibodies against FMDV serotype O in swine sera. The developed method presented high diagnostic sensitivity and excellent diagnostic specificity, and it could detect a broad spectrum of antibodies against FMDV serotype O. The diagnostic performance, accuracy rate, and analytical sensitivity of ME-CLIA were compared with those of three commercial kits. The immune protection value of multiple-epitope recombinant vaccine detected using ME-CLIA was preliminarily determined by observation of clinical symptoms postimmunization challenge, the results of which indicated that the ME-CLIA can be employed as a matching detection method for evaluating multiple-epitope recombinant vaccine. The percent positive values of ME-CLIA determined using swine vaccinated with inactivated vaccine were significantly positively correlated with the titers of liquid-phase-blocking enzyme-linked immunosorbent assay (ELISA) (LBPE) (genus in the Eriocitrin family and is classified into seven serotypes (A, O, C, Asia 1, SAT 1, SAT 2, and SAT 3), with each serotype containing numerous topotypes (1). FMDV serotype O (FMDV O) is widely prevalent around the world, and the World Reference Laboratory for Foot-and-Mouth Disease has divided FMDV O into 11 topotypes based on the differences in the VP1 sequence Eriocitrin and enzootic areas (https://www.wrlfmd.org/fmdv-genome/fmd-prototype-strains). Currently, the Mya-98 lineage of the Southeast Asia (SEA) topotype, Cathay topotype, and PanAsia lineage and the Ind-2001d lineage of the Middle East-South Asia (ME-SA) topotype Eriocitrin are prevalent in China. The diagnosis and control of FMD is complicated because vaccination and infection with one serotype does not cross-protect against other serotypes and may only be partially effective against some strains of the same serotype (2,C5). FMD control in enzootic areas depends on vaccination with inactivated vaccines (6, 7). The measurement of vaccine potency and monitoring of specific antibody coverage rates in the vaccinated areas are critical for the control and eradication of FMD. The standard potency test for FMD vaccines is the vaccination challenge test. However, considering practicability and animal welfare, indirect tests can be used as long as the correlation is validated to expectancy of protection in the target animal (5). Indirect tests, including the virus neutralization test (VNT) (8) and liquid-phase-blocking enzyme-linked immunosorbent assay (ELISA) (LPBE) (9,C11), have been recommended by the Office International des Epizooties. Although the VNT is the most effective method to evaluate vaccine potency, it requires cell culture facilities and uses live virus, which limit its application. LPBE, Eriocitrin which is being applied worldwide, employs polyclonal antisera (rabbit antisera and guinea pig antisera) and is quicker NPHS3 to perform, more reproducible, and correlates well with the VNT (12); however, it has a few drawbacks, such as high false-positive result rates, particularly when testing stressed cattle; low testing capacity; and many reaction steps (12,C14). In contrast, solid-phase competition ELISA (SPCE), developed by Mackay et al. using the same reagents as those employed in LPBE, has improved specificity and retains other characteristics (12, 14). Subsequently, to improve the detection performance, LPBE and SPCE were developed based on serotype-specific monoclonal antibodies (MAbs) instead of polyclonal antisera (4, 14,C16). However, the inactivated FMDV utilized as the diagnostic antigen in these methods presents considerable risk during the process of production and handling of live virus. In addition, FMDV is an RNA virus prone to genetic variation, which makes it difficult to screen serotype-specific MAbs. The blocking ELISA of O, A, and Asia 1, developed using the corresponding serotype-specific MAbs as the detecting antibodies, exhibited cross-reaction with the strongly positive serum of heterologous serotypes, although the serotype-specific MAbs did not react with heterologous serotype inactivated FMDV, possibly because the epitope on the antigen surface was blocked by steric Eriocitrin hindrance or conformational changes induced by antibodies binding to other epitopes (17,C20). Five neutralizing antigenic sites that have been identified and mapped on FMDV O lie on the structural proteins VP1, VP2, and VP3, which are located on the surface of the virus, but not on VP4, which is located inside the virus particle. Among the five neutralizing antigenic sites, only site 1 is linear, whereas the remaining four identified sites are conformational. Site 1 includes the G-H.