A Comparison between the Effect of an Avian Reovirus and Infectious Bursal Disease Virus on Selected Aspects of the Immune System of the Chicken

Abstract

Reovirus 81-176 was inoculated subcutaneously into day-old specific-pathogen-free leghorns and evaluated for its effects on the immune system over a 3-week period. Structural criteria included organ weights of the bursa of Fabricius (BF) and spleen (SP), scoring of histological lesions in the BF, SP, and thymus, and hematological analyses of the circulating leukocytes. Alterations in the functional capacity of the immune system were measured using the graft-versus-host reaction, the response of peripheral blood lymphocytes (PBLs) to mitogens, the ability of circulating monocytes to phagocytize latex beads, and the serological responses to Newcastle disease virus, sheep red blood cells, and Brucella abortus antigens. For comparison, infectious bursal disease virus (IBDV) was similarly evaluated by most of the same tests. Structurally, reovirus 81-176 altered BF and SP organ weights, the total numbers of white blood cells in circulation, and the degree of follicular atrophy in the BF. Functionally, reovirus inoculation reduced both the response of PBLs to the phytohemagglutinin-P stimulation and monocyte uptake of latex beads. According to the protocols used here, no significant alteration in B-cell function could be detected in reovirus-infected chicks. With the exception of leukocyte hematology, IBDV-infected chicks had significantly altered responses in all tests used. By way of comparison, the effects of IBDV were more persistent and pronounced than were those seen with reovirus. The graft-versus-host reaction indicated an elevated and/or uninhibited response of T-cells in the blood of IBDV-infected chicks.

Morphological Expression of Immunosuppression in Poultry

“…It is in agreement with other data on the immunosuppressive character of MDV (Calnek 1986), of PBSs (Safe and Hutzinger 1987) and with quantitative aspects of the evaluation of morphological changes indicative of immunosuppression in MD (Rivas and Fabricant 1988;Winterfield et al1980), IBD and reovirus infection (Montgomery et al 1986) as well. Assessment of Si was only difficult in the spleen (Si 3 and 4) in agreement with Rivas and.Fabricant (1988) due to the anatomical structure and role of this organ in immunopathological processes in birds.…”

“…The lesion severity was scored using the following scale (based on our own previous resultssee Jurajda (1985, 1986) and those of Winterfield et al (1980), Montgomery et al (1986) as well as Rivas and Fabricant (1988) Reduced cellularity of diffuse lymphoid tissue that envelops the central and penicillar arteries. Sporadic foci of necrotic lymphocytes occur in GC ("nodular lymphatic centres") along with proliferation of RE of the capillary sheaths (plate VII, Fig.…”

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

“…The poults in this experiment presented mild clinical disease although some TRV isolates did cause significant body weight decrease as indicated by Spackman et al 44 An effect reported for reovirus infection is the induction of immunosuppression, predisposing the host to infection with other pathogens, which would account for the diversity of syndromes associated with reovirus. 23,25,33,40 The bursal lymphoid depletion caused by the TRV isolates could induce a transient and possibly permanent immunosuppression in young infected turkeys. A difference in pathogenicity was observed between the TRVs studied.…”

Blue wing disease of chickens: Isolation of avian reovirus and chicken anaemia agent

“…Avian reoviruses do not seem to affect the immune system as seriously as MDV, IBDV or REV do. However, Montgomery et al (1986) have shown that their reovirus strain reduced the weight of bursa of Fabricáis and spleen, the total numbers of white blood cells in circulation and caused a follicular atrophy in the bursa of Fabricius. These authors reported on a functional reduction in the T-cell response.…”