Turkey Arthritis Reovirus Diagnostic Submission Analysis And Development Of A Serological Test

Abstract

Turkey reovirus (TRV) has been associated with several clinical syndromes including lameness, enteritis, myocarditis, and immunosuppression in turkey flocks. Lameness and enteritis are the current field problems and an increase in cases of lameness has been reported, possibly due to the emergence of novel genotypes of the virus. It is, therefore, important to understand factors responsible for this increase and to devise methods for the rapid detection of the virus and its antibodies. Currently, TRV is detected through RT-PCR and virus isolation but no specific serological test is available to detect anti-TRV antibodies in turkeys. In this thesis, I report a retrospective analysis of lameness submissions to the University of Minnesota Veterinary Diagnostic Laboratory (UMN-VDL) in the last eight years and confirm that submission of TRV positive cases has indeed increased. There were some months during which the probability of positive cases was numerically high. In addition, the submission of reovirus-positive lameness cases came from many different states indicating that the problem is widespread. There was a positive correlation between age of the turkey and TRV-related lameness; the number of TRV positive cases increased as the flocks aged. In addition, I developed a whole-virus ELISA (enzyme-linked immunosorbent assay) to detect anti-TRV antibodies. The TRV isolate used for this ELISA was a representative of several TRV genotypes based on Sigma C and B conserved epitopes. The test was validated using serum samples from experimental and clinical cases of TRV. At 0.4 cut-off, the diagnostic sensitivity and specificity of this ELISA were 0.92. In summary, the development of an ELISA with high sensitivity and specificity should provide an opportunity for early diagnosis of reovirus exposure and to follow the dynamics of reovirus immune response over time.