Isolation of a Reovirus from Poult Enteritis and Mortality Syndrome and Its Pathogenicity in Turkey Poults

Abstract

Poult enteritis and mortality syndrome (PEMS) is an acute, infectious intestinal disease of turkey poults, characterized by high mortality and 100% morbidity, that decimated the turkey industry in the mid-1990s. The etiology of PEMS is not completely understood. This report describes the testing of various filtrates of fecal material from control and PEMS-affected poults by oral inoculation into poults under experimental conditions, the subsequent isolation of a reovirus, ARV-CU98, from one of the PEMS fecal filtrates, and in vivo and in vitro studies conducted to determine the pathogenicity of ARV-CU98 in turkey poults. In order to identify a filtrate fraction of fecal material containing a putative etiologic agent, poults were challenged in two independent experiments with 220- and 100-nm filtrates of fecal material from PEMS-negative and PEMS-positive poults. The 100-nm filtrate was chosen for further evaluation because poults inoculated with this filtrate exhibited mortality and significantly lower (P < or = 0.05) body weight and relative bursa weight, three clinical signs associated with PEMS. These results were confirmed in a third experiment with 100-nm fecal filtrates from a separate batch of PEMS fecal material. In Experiment 3, body weight and relative bursa and thymus weights were significantly lower (P < or = 0.05) in poults inoculated with 100-nm filtrate of PEMS fecal material as compared with poults inoculated with 100-nm filtrate of control fecal material. Subsequently, a virus was isolated from the 100-nm PEMS fecal filtrate and propagated in liver cells. This virus was identified as a reovirus on the basis of cross-reaction with antisera against avian reovirus (FDO strain) as well as by electrophoretic analysis and was designated ARV-CU98. When inoculated orally into poults reared under controlled environmental conditions in isolators, ARV-CU98 was associated with a higher incidence of thymic hemorrhaging and gaseous intestines. In addition, relative bursa and liver weights were significantly lower (P < or = 0.05) in virus-inoculated poults as compared with controls. Virus was successfully reisolated from virus-challenged poults but not from control birds. Furthermore, viral antigen was detected by immunofluorescence in liver sections from virus-challenged poults at 3 and 6 days postinfection and virus was isolated from liver at 6 days postinfection, suggesting that ARV-CU98 replicates in the liver. In addition to a decrease in liver weight, there was a functional degeneration as indicated by altered plasma alanine aminotransferase and aspartate aminotransferase activities in virus poults as compared with controls. Although this reovirus does not induce fulminating PEMS, our results demonstrated that ARV-CU98 does cause some of the clinical signs in PEMS, including intestinal alterations and significantly lower relative bursa and liver weights. ARV-CU98 may contribute directly to PEMS by affecting the intestine, bursa, and liver and may contribute indirectly by increasing susceptibility to oppor...

Pathology and Virus Tissue Distribution of Turkey Origin Reoviruses in Experimentally Infected Turkey Poults

“…Diseases associated with avian origin reoviruses include viral arthritis/infectious tenosynovitis, malabsorption syndrome, stunting-runting syndrome, and various disorders characterized by pericarditis/myocarditis, chronic respiratory syndrome, nephritis, and multifocal necrotic hepatitis. 1,3,4,[8][9][10][11]21,25,31,38,47,50 Avian reoviruses have also been associated with immunosuppression 24,40 and atrophy of the bursa of Fabricius with characteristic lymphoid depletion and proliferation of connective tissue. 23,24,27,29,36,38,48 Studies in turkeys involving experimental reovirus infection have produced viral arthritis 2,19,30 and poult enteritis, 7,9,20,26,35,42 although descriptions of microscopic lesions caused by turkey-origin reoviruses (TRVs) are limited.…”

“…In the more severe forms, runting, immune dysfunction, and mortality occur. 5 Reovirus has been isolated from turkeys with PEMS 9,42 and its milder form, poult enteritis complex. 15,44 Recently, several TRVs collected from commercial turkey flocks affected with poult enteritis were shown to be genetically distinct from previously reported chicken reoviruses.…”

Viral Agents Associated with Poult Enteritis in Croatian Commercial Turkey Flocks

“…However, Heggen-Peay et al (2002) demonstrated that strain ARV CU98 isolated from PEMS poults does cause some of the clinical signs in PEMS. We aligned published S3 sequences of NC 98, PEMS 85 and TX and designed primers which amplify 460 bp-portion of S3 gene.…”

“…Carver et al (2001) found flocks with PEMS that were negative for turkey coronavirus. Other viruses that play an important role in the aetiology of PEMS are astroviruses Koci et al 2000) and reoviruses (Simmons et al 2000, Heggen-Peay et al 2002. More recently, PEMS has been described affecting poults in Great Britain, resulting in a first report of this disease there (Culver et al 2006).…”

“…Avian reoviruses (ARV) have been isolated from turkeys with PEMS (Heggen-Peay et al 2002) and also from chickens and ducks with enteric and respiratory problems, viral arthritis/tenosynovitis, malabsorption and stunting (Rosenberger and Olson 1997).…”