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Electron microscopic and immunohistochemical localization of Marek's disease (MD) herpesvirus particles in MD skin
1Department of Disease Control, School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Abstract:
Skin lymphomas induced in 11 specific-pathogen-free chickens by inoculation at 1 day of age with Marek's disease virus (MDV) were biopsied weekly and examined by electron microscopy and immunohistochemistry. In the sequentially biopsied lymphomas, immature MDV particles (abortive replication) were found only in the nuclei of necrotic lymphoblasts within necrotizing neoplasms. The necrotizing lymphomas were observed in two of the 11 experimental birds and were associated with prominent vascular endothelial cell injury, including fibrinoid necrosis of blood vessels. Nonnecrotizing lymphomas biopsied sequentially from the 11 experimental birds did not contain virus particles of any kind in the lymphoblasts and had no distinct vascular lesions. Immunohistochemically, MDV early antigen (pp38), but not late antigens (glycoproteins B and C), was detected only in the necrotizing lymphomas. These findings indicate that abortive MDV replication mainly occurred in necrotic lymphoblasts, which might have been induced by ischemia.
Insights
Marek's disease virus (MDV) can cause skin lymphomas in chickens. Abortive MDV replication was observed in necrotic lymphoblasts within necrotizing lymphomas, suggesting ischemia may play a role.
Area of Science:
- Veterinary Pathology
- Virology
- Oncology
Background:
- Marek's disease virus (MDV) is a herpesvirus known to cause lymphomas in chickens.
- Understanding the pathogenesis of MDV-induced lymphomas, particularly skin lymphomas, is crucial for disease control.
Purpose of the Study:
- To investigate the viral and cellular events occurring in Marek's disease virus-induced skin lymphomas in chickens.
- To differentiate between necrotizing and non-necrotizing lymphoma types based on viral replication and vascular changes.
Main Methods:
- Induction of skin lymphomas in specific-pathogen-free chickens using MDV.
- Weekly biopsies of lymphomas for examination via electron microscopy and immunohistochemistry.
- Detection of MDV antigens (early pp38, late glycoproteins B and C).
Main Results:
- Abortive MDV replication (immature particles) was identified in the nuclei of necrotic lymphoblasts within necrotizing lymphomas.
- Necrotizing lymphomas in two birds showed vascular endothelial cell injury and fibrinoid necrosis of blood vessels.
- Non-necrotizing lymphomas lacked detectable virus particles and distinct vascular lesions.
- MDV early antigen (pp38) was present only in necrotizing lymphomas, while late antigens were not detected.
Conclusions:
- Abortive MDV replication appears primarily associated with necrotic lymphoblasts in necrotizing lymphomas.
- Vascular injury, potentially induced by ischemia, may contribute to the development of necrotizing lymphomas.
- The absence of late viral antigens in necrotizing lymphomas suggests a role for early viral events or host responses in pathogenesis.