Development and Evaluation of a Monoclonal Antibody-Based Blocking Enzyme-Linked Immunosorbent Assay for the Detection of Antibodies against Novel Duck Reovirus in Waterfowl Species.

The novel duck reovirus (NDRV) is an emerging pathogen that causes disease in various waterfowl species. Since the outbreak, it has caused huge economic losses to the duck industry in China. A rapid, reliable, and high-throughput method is required for epidemiological investigation and evaluation of vaccine immunogenicity. A good first step would be establishing an enzyme-linked immunosorbent assay (ELISA) that could detect NDRV antibodies in different breeds of ducks and geese from the serum and egg yolk. This study used a recombinant NDRV σB protein and a corresponding horseradish peroxidase (HRP)-labeled monoclonal antibody to develop a blocking ELISA (B-ELISA). The cutoff value of the B-ELISA was 37.01%. A total of 212 serum samples were tested by the B-ELISA, and the virus neutralization test (VNT) was the gold standard test. The sensitivity and specificity of the B-ELISA were 92.17% (106/115) and 97.94% (95/97), respectively. The agreement rates between the B-ELISA and VNT were 94.81% (kappa value, 0.896). The B-ELISA could specifically recognize anti-NDRV sera without cross-reacting with other positive serums for other major diseases in ducks and geese. The inter- and intra-assay coefficients of variation (CVs) of the B-ELISA and VNT assays were acceptable. In conclusion, the novel B-ELISA could be a rapid, simple, safe, and economically attractive alternative to the VNT in assessing duck flocks' immunity status and in epidemiological surveillance in multiple waterfowl species. NDRV disease is a new epidemic disease in waterfowl that first appeared in China. Compared with the classical DRV (CDRV), NDRV is associated with more severe symptoms, a higher mortality rate, and a broader host range. NDRV has become the prevalent genotype in China. At present, there are no commercially available diagnostic products for the NDRV disease. VNT, as the gold standard serologic test, is not only time-consuming and laborious, but also has high requirements for facilities and equipment, which is not suitable for clinical application. Conventional ELISA requires specific antispecies conjugates that are not currently available. B-ELISA not only has the advantage of higher analysis specificity, but also can be used to test specific antibodies against different waterfowl species, because no species-specific conjugates are required in such detection. Therefore, it is necessary to establish a B-ELISA for the detection of antibodies against NDRV in waterfowl species.