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Simian immunodeficiency virus-induced meningoencephalitis: natural history and retrospective study
D J Ringler1, R D Hunt, R C Desrosiers
1New England Regional Primate Research Center, Harvard Medical School, Southborough, MA 01772.
Abstract:
Simian immunodeficiency virus (SIV) is a lentivirus with morphological and antigenic similarities to human immunodeficiency virus, the causative agent of acquired immunodeficiency syndrome (AIDS) of humans. Macaque monkeys infected with SIV show profound immunological impairment, clinically characterized by multiple opportunistic infections and neoplasms. Retrospective examination of autopsy tissue from 27 SIV-infected animals demonstrated that approximately 60% of the experimentally inoculated animals had a meningoencephalitis characterized by perivascular infiltrates of macrophages and multinucleate giant cells in the white and gray matter and leptomeninges. Ultrastructurally, these macrophages contained typical lentiviral particles within membrane-bound intracytoplasmic vacuoles. Other findings in the central nervous system included discrete randomly located neuroglial nodules, endothelial hypertrophy, and leptomeningeal thickening. The results indicate tha the meningoencephalitis induced by SIV in monkeys is similar to the lesions of the central nervous system in patients with AIDS and that SIV infection in the macaque is a useful animal model to study the pathogenesis of human immunodeficiency virus--related subacute encephalitis or AIDS encephalopathy.
Insights
Simian immunodeficiency virus (SIV) causes severe immune impairment in macaques. SIV infection in macaques leads to meningoencephalitis, a brain inflammation similar to that seen in human immunodeficiency virus (HIV)-related encephalopathy.
Area of Science:
- Veterinary Pathology
- Virology
- Neuroscience
Background:
- Simian immunodeficiency virus (SIV) is a lentivirus.
- SIV shares similarities with human immunodeficiency virus (HIV), the cause of acquired immunodeficiency syndrome (AIDS).
- SIV infection in macaques results in significant immunological impairment, marked by opportunistic infections and neoplasms.
Purpose of the Study:
- To investigate the central nervous system (CNS) lesions in SIV-infected macaques.
- To compare SIV-induced meningoencephalitis in macaques with HIV-related encephalopathy in humans.
- To establish the macaque as a model for studying HIV-related CNS diseases.
Main Methods:
- Retrospective autopsy tissue examination of 27 SIV-infected macaques.
- Histopathological analysis of brain and leptomeningeal tissues.
- Ultrastructural examination of macrophages for lentiviral particles.
Main Results:
- Meningoencephalitis was observed in approximately 60% of SIV-infected macaques.
- Lesions included perivascular infiltrates of macrophages and multinucleated giant cells in the CNS.
- Ultrastructural analysis confirmed lentiviral particles within macrophages; other findings included neuroglial nodules and endothelial hypertrophy.
Conclusions:
- SIV-induced meningoencephalitis in macaques closely resembles CNS lesions in human AIDS patients.
- SIV-infected macaques serve as a valuable animal model for studying the pathogenesis of HIV-related subacute encephalitis and AIDS encephalopathy.