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Summary
Maedi virus infection in Finnish sheep shows early immune responses like lymphocyte stimulation and antibody production. Virus is detectable in blood and tissues, with mild central nervous system inflammation after direct brain inoculation.
Area of Science:
- Veterinary Virology
- Immunology
- Sheep Pathology
Background:
- Maedi virus causes progressive pneumonia and neurological disease in sheep.
- Understanding the early pathogenesis and immune response is crucial for disease control.
Purpose of the Study:
- To characterize the early immune responses and virus distribution following experimental maedi virus infection in sheep.
- To compare the effects of respiratory versus intracerebral inoculation routes.
Main Methods:
- Ten Finnish sheep were inoculated via respiratory tract or intracerebrally with maedi virus.
- Lymphocyte stimulation, antibody production (complement fixing and neutralizing), virus recovery, and histopathology were monitored.
Main Results:
- Virus-specific lymphocyte stimulation and complement-fixing antibodies appeared within weeks to months post-infection, varying by route.
- Neutralizing antibodies were detected later, primarily after four months.
- Maedi virus was consistently recovered from blood leucocytes and tissues; cerebrospinal fluid also yielded virus after intracerebral inoculation.
- Respiratory infection led to early maedi lesions, while intracerebral inoculation caused minimal central nervous system inflammation.
Conclusions:
- Both respiratory and intracerebral maedi virus inoculation induce detectable immune responses and systemic virus presence.
- The route of infection influences the timing of immune responses and the observed pathological changes, with minimal CNS pathology noted even after direct inoculation.