Development and validation of a competitive ELISA based on bacterium-original virus-like particles of serotype O foot-and-mouth disease virus for detecting serum antibodies

Abstract

Foot-and-mouth disease (FMD) is a highly contagious disease that affects all susceptible cloven-hoofed animals, resulting in considerable economic losses to animal industries worldwide. Numerous categories of enzyme-linked immunosorbent assays (ELISA) have been developed and widely used to evaluate herd immunity. Manufacturing inactivated FMD virus (FMDV) as a diagnostic antigen requires a facility with a high level of biosafety, but this requirement raises concern on viral leakage. In our previous study, bacterium-original FMD virus-like particles (VLPs) resemble the authentic FMDV and induce protective immunity against homologous viral challenges, thereby demonstrating that they are sufficiently safe without limitations on biosafety facilities and easily prepared. Herein, we developed a competitive ELISA (cELISA) based on FMDV-VLPs as a diagnostic antigen to evaluate herd immunity. The criterion of this cELISA was determined by detecting panels of positive sera with different antibody titers and negative sera. The working parameter of cELISA was optimized, and samples with a percentage inhibition of ≥ 50% were considered positive. The specificity of cELISA to test 277 serum samples with various antibody titers was 100%, and the sensitivity reached 96%. The coincidence rates of cELISA with a VDPro® FMDV and a PrioCHECK® FMDV type O antibody ELISA kit were 97.8% and 98.2%, respectively. Repeatability tests demonstrated that the coefficients of variation within and between runs were less than 7% and 14%, respectively. Our data demonstrated that cELISA based on bacteriumoriginal VLPs had high specificity, sensitivity, and reproducibility. The cELISA could also be used for evaluating vaccination herd immunity effects, especially in developing countries.

The Use of Distinctive Monoclonal Antibodies in FMD VLP- and P1-Based Blocking ELISA for the Seromonitoring of Vaccinated Swine

“…Scientists are currently attempting to reform the format of blocking ELISA to detect protective antibodies against FMDV [ 16 , 17 , 18 , 19 , 23 , 24 ]. However, to our knowledge, no comparative studies of different tracers and different antigens using VLPs and P1 have been reported.…”

“…In the beginning, the solid-phase competition ELISA (SPCE) format used polyclonal antisera as capture antibodies and tracers, with inactivated, purified viruses as antigens [ 17 ]. Later on, polyclonal antibodies were replaced by MAbs as the tracer and capture for large-scale serology [ 18 ], and VLPs replaced inactivated viruses, whose manufacture was limited to BSL3 laboratories [ 18 , 19 ]. A recombinant VP2 subunit protein from the Egyptian SAT2 isolate and a P1 capsid polyprotein of serotype O were also chosen as the diagnostic antigens [ 20 , 21 ].…”

Şap virüsü şuşlarına karşı poliklonal antikor üretimi

“…However, Brocchi reported that imperfect FMDV type specificity and a different assay standardization for each FMDV serotype are some test limitations of these kits. In addition to monoclonal Ab based kits, a cocktail of polyclonal or monoclonal Abs usage, chimeric antibodies, recombinant Ab production, virus-like particles, or recombinant proteins have also been studied (Ko et al 2009;Yang et al 2017;Cao et al 2018, Ran et al 2019.…”