Submitted to: Veterinary Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/25/2006
Publication Date: 2/28/2007
Citation: Pantin Jackwood, M.J., Spackman, E., Day, J.M. 2007. Pathology and virus tissue distribution of turkey origin reoviruses in experimentally infected turkey poults. Veterinary Pathology. 44:185-195. Interpretive Summary: Not required.
Technical Abstract: The pathogenesis of four isolates of turkey-origin reovirus (TRV) and one chicken-origin reovirus was examined by infecting specific pathogen free (SPF) poults. These TRV isolates were collected from turkey flocks experiencing poult enteritis and are genetically distinct from previously reported avian reoviruses. Microscopic examination of the tissues collected from the TRV-infected poults revealed different degrees of bursal atrophy characterized by lymphoid depletion and increased fibroplasia between the bursal follicles. In order to understand the relationship between virus spread and replication, and the induction of lesions, immunohistochemical staining (IHC) for viral antigen, in situ hybridization (ISH) for the detection of viral RNA, and the TUNEL assay for the detection of apoptosis in affected tissues was performed. Both IHC and ISH revealed viral antigen and RNA in the surface epithelial cells of the bursa, in macrophages in the interstitium of the bursa, and to lesser degree, in splenic red pulp macrophages and intestinal epithelial cells. Increased apoptosis of bursal lymphocytes and macrophages was observed at 2 and 5 days post-inoculation. No lesions were found in tissues from poults inoculated with the virulent chicken-origin strain 1733, however viral antigen was detected in the bursa and the intestine. Although all TRV’s studied displayed similar tissue tropism, there were substantial differences in the severity of lesions produced. The lymphoid depletion observed in the bursa appears to be the effect of an indirectly induced apoptosis and would most likely result in immune dysfunction in poults infected with TRV.