Development of Competitive ELISA for Detection of Avian Metapneumovirus Antibodies in Chicken

Avian metapneumovirus (aMPV) causes an acute and highly contagious upper respiratory tract infection in turkeys and chickens. In this study, a competitive ELISA (C-ELISA) was developed for the detection of antibodies to aMPV in chicken sera and/or their egg yolks. This assay is based on the competitive binding of monoclonal antibody with serum antibodies to recombinant aMPV N protein expressed by a recombinant baculovirus. The C-ELISA showed specificity and sensitivity of 100% and 98.0%, respectively, when compared to the virus neutralization test. In specific pathogen-free chickens experimentally infected with aMPV SC1509 strain, the C-ELISA started to detect antibodies to aMPV as early as 5 days post infection from birds infected with aMPV, while a commercial ELISA kit detected first 10 days post infection. The C-ELISA was similar or superior to a commercial ELISA kit when serum and egg yolk samples collected from chickens on six outbreak farms were tested for diagnosis. The C-ELISA developed in the present work provides a short turnaround time and can be a useful diagnostic and screening tool for aMPV infection in the field.