Submitted to: Avian Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 15, 2005
Publication Date: August 2, 2005
Citation: Spackman, E., Pantin Jackwood, M.J., Day, J.M., Sellers, H. 2005. The pathogenesis of turkey origin reoviruses in turkeys and chickens. Avian Pathology 34(4):291-296. Interpretive Summary: Enteric disease has caused great economic losses to the turkey industry because birds affected by the disease may become sick and die, and more often do not grow and are stunted. The cause of this disease is not currently known, however numerous agents have been implicated and it is believed that they work in combination to cause disease. One agent, avian reovirus, which is very common in chickens and turkeys was recently discovered to have new strains that were genetically different from previously described reoviruses. In order to determine if this viral agent was involved in causing enteric disease and stunting, pathogenesis studies were performed with chickens and turkeys. These agents neither caused disease in chickens nor did they infect them. In turkeys, they caused mild disease, but damaged some organs of the immune system severely which may cause the immune system to not function effectively, thus allowing other agents to cause disease. Additionally, it was found that these viruses did cause decreases in body weight.
Technical Abstract: Avian reoviruses that have been shown to be genetically distinct from chicken origin reoviruses were isolated from commercial turkey flocks in the Southeastern U.S. and Texas which were experiencing enteritis. These turkey origin reoviruses (TRV's) were evaluated for their pathogenesis in commercial poults, SPF poults and SPF chickens. Mortality, clinical disease, gross lesions, microscopic lesions and body weights were observed through day 17 post exposure. Turkey origin reoviruses replicated poorly and did not cause disease in chickens. Disease induced by the TRV isolates was similar in both SPF and commercial origin poults. Among all isolates clinical disease in poults, characterized by diarrhea and depression, was mild and gross lesions were absent. Mortality was minimal and did not differ among the treatment groups. Several TRV isolates did cause moderate to severe bursal atrophy in poults. Additionally, each of the TRV isolates caused significant body weight decreases in SPF and/or commercial poults as compared to sham inoculates. Molecular characterization of the isolates revealed that the TRV's had identical electropherotype profiles to those of the CRV's.