Chemiluminescence immunoassay for the detection of antibodies against the 2C and 3ABC nonstructural proteins induced by infecting pigs with the foot-and-mouth disease virus

Liu Z, Shao J, Zhao F, Zhou G, Gao S, Liu W, Lv J, Li X, Li Y, Chang H, Zhang Y

Clin  Vaccine  Immunol

2017 Jun 7. pii: CVI.00153-17. doi: 10.1128/CVI.00153-17

Abstract:

The potential diagnostic value of chemiluminescence immunoassays (CLIAs) has been accepted in recent years, although its use for foot-and-mouth disease (FMD) diagnostics has not been reported. Full-length 3ABC and 2C proteins were expressed in bacteria and purified by affinity chromatography to develop a rapid and accurate approach to distinguish pigs infected with foot-and-mouth disease virus (FMDV) from vaccinated pigs (DIVA). The recombinant proteins were then used as antigens to develop two CLIAs for the detection of antibodies against nonstructural viral proteins. The diagnostic performance of the two assays was compared by analyzing pig sera (naïve, n = 63; vaccinated, uninfected, n = 532; naïve, infected, n = 117) with a known infection status. The 3ABC-2C CLIA had a higher accuracy rate, with a diagnostic sensitivity of 100 % and a diagnostic specificity of 96.5 %, than the 3ABC CLIA, which had a diagnostic sensitivity of 95.7 % and a diagnostic specificity of 96.0 %. The 3ABC-2C CLIA also had a high concordance rate (96.2 % and 97.8 %) with two commercial FMDV ELISA kits used to assess sera collected from 962 pigs in the field. Compared with the commercial ELISA kits, the 3ABC-2C CLIA detected infection earlier in serum samples from infected pigs. In addition, the 3ABC-2C CLIA produced results within 15 min. Based on these findings, the 3ABC-2C CLIA could serve as the foundation for the development of pen-side FMD diagnostics and offers an alternative method to detect FMDV infections.