TY - JOUR N2 - Newcastle disease (ND) is a highly contagious and economically important disease in the poultry industry caused by avian avulavirus-1, historically known as Newcastle disease virus (NDV). Control of ND primarily relies on prophylactic vaccination of flocks, and many vaccines are available on the market, both conventional and more recently introduced new generation recombinant types. To assess the protection level achieved by vaccination ELISA tests are typically used, they also are to track an infection with field strains in non-vaccinated flocks. Special modifications of ELISA can be used as a screening tool to detect infection in flocks vaccinated with new generation vaccines. In this study, we have developed an ELISA test for the detection of antibodies against the nucleoprotein (NP) of NDV and for differentiation of chickens vaccinated with commercial and prototype in-house recombinant vector vaccines from those infected with field NDV strains. The NP gene of LaSota NDV strain expressed in a baculovirus vector was used as a coating antigen in the ELISA. The developed test was optimized, validated and compared to other serological tests. The sensitivity, specificity and accuracy of recombinant NP protein-based ELISA were respectively 96.1%, 96.3%, and 96.2%. Inter-rater (kappa) agreement between the NP-ELISA and the gold standard HI test was calculated to be 0.995. In our comparisons, commercially available ELISA tests revealed different specificities ranging from 95.5–100% and sensitivities at variance, ranging from 90.1 to 99.0%. A high level of maternally derived antibodies was measured in the serum of 1-day-old broilers in the NP-ELISA assay. These antibodies had disappeared and were undetected at 3, 5 and 6 weeks post-vaccination but birds became positive again at 2 weeks after control infection with a velogenic NDV strain. In SPF chickens, antibodies against NP protein were detected only after a challenge. The recombinant NP protein-based ELISA test is sensitive, specific and accurate when compared to the gold standard HI test and commercially available kits. Moreover, the method could be also used for the differentiation between vaccinated and infected birds. L1 - http://www.czasopisma.pan.pl/Content/113457/PDF/12.pdf L2 - http://www.czasopisma.pan.pl/Content/113457 PY - 2019 IS - No 3 EP - 531–540 DO - 10.24425/pjvs.2019.129961 KW - Newcastle disease virus KW - serology KW - Enzyme-Linked Immunosorbent assay KW - nucleoprotein KW - differentiation A1 - Domańska-Blicharz, K. A1 - Tyborowska, J. A1 - Sajewicz-Krukowska, J. A1 - Olszewska-Tomczyk, M. A1 - Rąbalski, Ł. A1 - Kucharczyk, K. A1 - Szewczyk, B. A1 - Śmietanka, K. PB - Polish Academy of Sciences Committee of Veterinary Sciences PB - University of Warmia and Mazury in Olsztyn VL - vol.22 DA - 2019.09.24 T1 - Development of a recombinant NP protein based indirect ELISA for the detection of antibodies against Newcastle disease virus and differentiation of infected or recombinant vaccine immunized chickens SP - 531–540 UR - http://www.czasopisma.pan.pl/dlibra/publication/edition/113457 T2 - Polish Journal of Veterinary Sciences ER -