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Pathogenesis of visna. IV. Spinal fluid studies
Summary
Visna virus infection in sheep leads to progressive paralysis. Cerebrospinal fluid analysis reveals early virus presence, followed by antibody production within the central nervous system (CNS), indicating disease progression.
Area of Science:
- Veterinary Neurology
- Immunology
- Virology
Background:
- Visna is a persistent retroviral infection in sheep.
- It causes chronic, progressive paralytic disease with long incubation periods.
- Understanding the immune response within the central nervous system (CNS) is crucial.
Purpose of the Study:
- To investigate the dynamics of visna virus and the immune response in the cerebrospinal fluid (CSF) of infected sheep.
- To correlate CSF findings with disease progression and clinical outcomes.
Main Methods:
- Intracerebral infection of Icelandic sheep with visna virus.
- Repeated cerebrospinal fluid (CSF) sampling up to 42 months post-infection.
- Isolation of infectious virus, antibody titration (serum and CSF), and cell counts in CSF.
Main Results:
- Infectious visna virus was detected in CSF early post-infection (up to 4 months).
- CSF neutralizing antibodies appeared subsequently, sometimes exceeding serum levels, suggesting local CNS production.
- Increased CSF leukocytes (macrophages, lymphocytes, plasma cells) correlated with progressive CNS disease, higher viral loads, and clinical paralysis.
Conclusions:
- Local antibody production within the CNS occurs during visna virus infection.
- CSF leukocyte counts serve as an indicator of progressive neurological disease and disease severity.
- These findings highlight the importance of CSF analysis in managing visna virus infections in sheep.