Effects of experimental immunosuppression on reovirus‐induced tenosynovitis in light‐hybrid chickens

Abstract

SUMMARYGroups of specific pathogen-free light-hybrid chickens which had been immunosuppressed either by surgical thymectomy (Tx) or surgical bursectomy (Bx) or cyclophosphamide (Cy) treatment or Tx plus Cy treatment (Tx + Cy), as well as intact (untreated) birds, were inoculated with graded doses of an arthrotropic avian reovirus at 1 day of age and observed up to 5 weeks post-inoculation (p.i.). Cy-treatment with or without Tx considerably increased the mortality, incidence of gross leg lesions and severity of microscopic lesions due to reovirus infection. The Bx group showed only a significant increase in mortality, and the Tx group response was generally similar to the untreated group. Dead birds showed hepatic necrosis, which in Cy-treated groups (Cy, Tx + Cy) was associated with calcification. Surviving Cy-treated birds had acute tenosynovitis characterised grossly by large amounts of serous exudate in leg tendon sheaths, and microscopically by a massive heterophilic but only mild lymphocytic infiltration of tendon sheaths. Tenosynovitis lesions in Bx birds were generally similar to those of the untreated chickens, i.e. grossly small amounts of yellowish brown gelatinous exudate and microscopically moderate chronic inflammatory changes in leg tendon sheaths. In Tx birds gross lesions were rarely seen and the microscopic lesions were often very mild.Reovirus could be recovered from cloacal swabs from untreated and Tx birds for 2 weeks, Bx birds for 3 to 4 weeks, and Cy and Tx + Cy chickens continuously throughout. Reovirus was isolated from tendon tissue of all Cy and Tx + Cy infected birds examined at 5 weeks p.i. and gross tenosynovitis lesions were seen in all birds. The virus was recovered from the tendons of only a proportion of the infected untreated, Tx and Bx groups, and overall more frequently from apparently normal birds. This was especially marked in the infected Tx group. Antibody responses as shown by gel precipitation and virus neutralisation were

Mixed infection of turkeys withMycoplasma synoviaeand reovirus: Field and experimental observations

“…In M. synoviae infection and in reovirus infection of the chicken, the cell mediated immune response appears to play a role in the development of systemic lesions, including inflammatory joint disease (Kume et al, 1977;Kibenge et al, 1987). If the same situation occurs in the turkey, it would be of interest to know if the day old poult is less susceptible because of a relatively immature cellular immune system.…”

Response of cyclophosphamide-treated broiler chickens to challenge with velogenic Newcastle disease virus

“…Cyclophosphamide (CY), a tumoricidal agent, has been used experimentally as an immunosuppressant in numerous pathogenicity studies to determine some aspects of the immune response such as the role of T and B cells in protective responses to infectious pathogens in chickens (Isogai et al 1980;Kibenge et al 1987;Corrier et al 1991;Okoye et al 1992;Reynolds and Maraqa 1999). CY treatment leaves the bursal reticulum intact and destroys only the lymphoid cells.…”

Características clínicas e anatomo-histopatologicas da infecção experimental mista por Orthoreovirus aviario e Mycoplasma synoviae em frangos de corte

“…A RIFI sugere a co-localização dos agentes, demonstrando a associação destes nos casos de artrites, sendo o ARV principalmente associado à superϐície de ϐibroblastos da camada externa da membrana sinovial e tendão ϐlexor digital e o MS na superϐície interna da cápsula articular, na membrana sinovial, junto ao endotélio vascular. Na infecção por MS ou ARV, a resposta imune mediada por células desempenha um papel fundamental na imunopatologia da doença, principalmente com relação às lesões artríticas (Kibenge et al 1987, Sentíes-Cué et al 2005) devendo ser considerada a ação sinérgica dos dois agentes na infecção mista (Kibenge et al 1987), visto que ARV (Ni & Kemp 1995) e MS (Sentíes-Cué et al 2005) estão associados a quadros de imunossupressão. A exemplo do que ocorre em outras infecções onde a patologia é agravada pela co-infecção por agentes imunossupressores, quadros gravíssimos podem ocorrer nos casos de infecção mista envolvendo ARV e/ou MS e o vírus da doença infecciosa da bursa (IBDV) que causa severa imunodepressão nos animais (Moradian et al 1990, Sentíes-Cué et al 2005.…”

“…Com a evolução da doença, as aves apresentam severa diϐiculdade de locomoção e tendem a apoiar sobre o tarso, caracterizando o quadro denominado de "perda de pernas" (Bottino 2009). Uma série de fatores deve ser considerada em relação ao agravamento das lesões artríticas, como manejo e nutrição deϐiciente, infecção por agentes oportunistas e mesmo a infecção concomitante por ambos os agentes (MS e ARV), provocando aumento na severidade do quadro patológico pela ação sinérgica dos mesmos (Kibenge et al 1987).…”