Immune-mediated pathogenesis of Borna disease

Area of Science:

• Veterinary Neurology
• Immunology
• Virology

Background:

• Borna disease is an endemic, progressive encephalomyelitis affecting horses and sheep in Central Europe.
• The Borna disease virus (BDV) can infect diverse animal species experimentally and has been detected in human psychiatric patients.
• The exact pathogenesis of Borna disease remains incompletely understood.

Purpose of the Study:

• To elucidate the immunopathological mechanisms underlying Borna disease pathogenesis.
• To investigate the role of the host immune response in the development of Borna disease.
• To characterize the specific immune cells involved in Borna disease.

Main Methods:

• Experimental infection of rats with Borna disease virus.
• Comparison of disease development in immunocompetent versus immunoincompetent rats.
• Adoptive transfer of immune cells from infected rats to naive recipients.
• Establishment and characterization of a virus-specific T cell line (CD4+).

Main Results:

• Immunoincompetent rats infected with Borna disease virus did not develop the disease, despite persistent viral replication.
• Adoptive transfer of immune cells from diseased rats induced Borna disease in immunoincompetent recipients.
• A virus-specific T cell line with a helper/inducer (CD4+) phenotype was successfully established.
• These CD4+ T cells were implicated in the pathogenesis of Borna disease.

Conclusions:

• Borna disease pathogenesis is primarily mediated by a virus-induced immunopathological reaction, not direct viral cytopathy.
• The disease likely results from a delayed-type hypersensitivity reaction orchestrated by CD4+ T cells.
• Understanding the immune mechanisms is crucial for managing Borna disease in susceptible animal populations.