The recombinant antigen obtained by cloning and expressing two IBV nucleocapsid protein fragments (143-414 aa, 281-414 aa) in Escherichia coli was used for the detection of avian infectious bronchitis virus (IBV) specific antibodies in chicken sera by the indirect ELISA (rNpIBV-ELISA). As a result of testing 1524 serum samples the diagnostic sensitivity and specificity of rNpIBV-ELISA when comparing those of the routine whole IBV ELISA have been shown to be 93.81% and 87.36%, respectively. The agreement value was 91.5%.

Recombinant foot-and-mouth disease virus (FMDV) proteins 3A, 3B, and 3AB were produced by expressing the corresponding genes in Escherichia coli and purified by metal-chelate affinity chromatography. The recombinant proteins were used as antigens in indirect enzyme-linked immunosorbent assay (ELISA) to differentiate between vaccinated and FMD-infected animals. The following parameters were determined: working concentrations of antigens and peroxidase conjugate of cattle anti-IgG, the optimum composition of blocking buffer, and the positive-negative threshold of the reaction. Tests performed with approximately 200 serum samples taken from animals of different immunity states showed that the protocol with protein 3A as the antigen (3A-ELISA) provided the most reliable differentiation. All the newly developed systems proved to outperform the commercial Chekit FMD-3ABC kit in sensitivity, and 3A-ELISA was no less specific.

No abstract

No abstract

Spread of porcine epidemic diarrhea and its increased threat for the pig industry necessitate development of advanced techniques for the disease diagnosis. Use of recombinant antigens of the disease agent seems prospective. The recombinant antigen-based indirect enzyme-linked immunosorbent assay has been developed for the detection of antibodies against porcine epidemic diarrhea virus. The research performed allowed for determination of all necessary test conditions. Basic features of the developed method were determined during its validation. The test precision was above 90% pursuant to its repeatability and reproducibility, diagnostic specificity of the test amounted to 99.47%, and its sensitivity as compared to commercial ID Screen PEDV Indirect (IDvet, France) was 92% with very good compatibility of the two tests (k-criterion – 0.88) – 92%. The test-system demonstrates high stability upon the change of the key test component.