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Immunohistology of malignant rabbit fibroma virus--a comparative study with rabbit myxoma virus
Abstract:
Malignant rabbit fibroma virus (MV) causes a syndrome that consists of disseminated malignant tumors and immunosuppression complicated by severe Pasteurella multocida infection and death. Tissues from rabbits given MV and rabbit myxoma virus were examined by direct immunofluorescence with the use of antibody against virus antigens. Primary and metastatic tumors caused by MV and rabbit myxoma virus were composed of soft tissue cells containing virus antigens. Skin appendages and epidermis overlying the respective tumors showed scant MV but abundant myxoma virus antigen. Both viruses were present systemically in the reticuloendothelial system. Epithelial cells from the liver, kidney, and lung of myxoma virus-infected rabbits contained virus, whereas in MV tumor-bearing rabbits, these cells were uninvolved. However, nasal mucosal and conjunctival epithelia, the locations of Pasteurella infection, showed squamous metaplasia and contained large amounts of MV and myxoma antigens. By analogy to other respiratory tract pathogens, these epithelial changes were probably etiologically significant for development of pasteurellosis in rabbits bearing virus-induced tumors. Thus by immunopathologic as well as clinical examination, MV produces a syndrome distinct from that seen with rabbit myxoma virus. MV induced severe immunosuppression despite T-lymphocyte hyperplasia in the lymphoid tissues observed. The combination of a systemic virus infection, epithelial alterations that impaired clearance mechanisms, and immunologic dysfunction is likely to contribute to the inability of rabbits given MV to survive their gram-negative infection.
Insights
Malignant rabbit fibroma virus (MV) causes distinct tumors and immunosuppression, increasing susceptibility to Pasteurella multocida. This viral infection impairs rabbit immunity and alters respiratory epithelia, leading to fatal secondary infections.
Area of Science:
- Veterinary Virology
- Immunopathology
- Oncology
Background:
- Malignant rabbit fibroma virus (MV) induces tumors and immunosuppression.
- Rabbits infected with MV are susceptible to secondary Pasteurella multocida infections.
- The pathogenesis of MV-induced disease is not fully understood.
Purpose of the Study:
- To investigate the immunopathologic features of malignant rabbit fibroma virus (MV) infection.
- To compare the effects of MV with rabbit myxoma virus.
- To elucidate the mechanisms underlying MV-induced susceptibility to secondary infections.
Main Methods:
- Direct immunofluorescence using antibodies against viral antigens.
- Examination of tissues from MV and myxoma virus-infected rabbits.
- Histopathological analysis of tumors and associated tissues.
Main Results:
- MV and myxoma virus antigens were detected in primary and metastatic tumors.
- Both viruses infected the reticuloendothelial system.
- MV induced squamous metaplasia in nasal and conjunctival epithelia, correlating with Pasteurella infection sites.
- MV caused severe immunosuppression despite T-lymphocyte hyperplasia.
Conclusions:
- MV induces a distinct syndrome characterized by tumors, immunosuppression, and epithelial alterations.
- Epithelial changes in the respiratory tract likely contribute to secondary Pasteurella infections.
- The combination of systemic viral infection, impaired clearance, and immunologic dysfunction leads to high mortality in MV-infected rabbits.