Detection of antibody to turkey coronavirus by antibody-capture enzyme-linked immunosorbent assay utilizing infectious bronchitis virus antigen

An antibody-capture enzyme-linked immunosorbent assay (ELISA) for detection of antibody to turkey coronavirus (TCV) utilizing infectious bronchitis vi rus (IBV) antigen was developed. Anti-TCV hyperimmune turkey serum and norm al turkey serum were used as positive or negative control serum for optimiz ation of the ELISA system. Goat anti-turkey immunoglobulin G (light plus he avy chains) conjugated with horseradish peroxidase was used as detector ant ibody. The performance of the ELISA system was evaluated with 45 normal tur key sera and 325 turkey sera from the field and the cutoff point was determ ined. Serum samples of turkeys experimentally infected with TCV collected s equentially from 1 to 63 days postinfection were applied to the established antibody-capture ELISA using IBV antigens. The optimum conditions for diff erentiation between anti-TCV hyperimmune serum and normal turkey serum were serum dilution at 1:40 and conjugate dilution at 1:1600. Of the 325 sera f rom the field, 175 were positive for TCV by immunofluorescent. antibody (IF A) assay. The sensitivity and specificity of the ELISA relative to IFA rest were 93.1% and 96.7%, respectively, based on the results of serum samples from the field turkey flocks using the optimum cutoff point of 0.18 as dete rmined by the logistic regression method. The ELISA values of all 45 normal turkey sera were completely separated from that of IFA-positive sera. The ELISA results of serum samples collected from turkeys experimentally infect ed with TCV were comparable to that of the IFA assay. Reactivity of anti-ro tavirus, anti-reovirus, anti-adenovirus, or anti-enterovirus antibodies wit h the IBV antigens coated in the commercially available ELISA plates coated with IBV antigens could be utilized for detection of antibodies to TCV in antibody-capture ELISA.