EVALUATION OF DIFFERENT TURKEY RHINOTRACHEITIS VIRUSES USED AS ANTIGENS FOR SEROLOGICAL TESTING FOLLOWING LIVE VACCINATION AND CHALLENGE

Two enzyme-linked immunosorbent assays (ELISA) developed in the author s' laboratory for turkey rhinotracheitis serological testing, a commer cial ELISA kit, and two virus-neutralization (VN) assays were compared with respect to the efficiency of these assays for serological monito ring in specific-pathogen-free (SPF) turkeys inoculated with four path ogenic isolates of turkey rhinotracheitis virus, with or without previ ous live vaccination. Both the live vaccine and the different isolates of virus were shown to induce antibody rises, the detectability of wh ich varied depending on the ELISA or VN assay used for serological tes ting. The results show that 3 weeks after vaccination with an attenuat ed strain, the choice of an inadequate antigen for serological testing may be the cause of an apparent lack of immunogenicity of the vaccine , and that 2 weeks after challenge, such a choice in ELISA can also hi nder the early diagnosis of a TRT virus infection in both vaccinated a nd unvaccinated turkeys.