Murine leukemia virus induced central nervous system diseases

Area of Science:

• Virology
• Immunology
• Neuroscience

Background:

• Moloney murine leukemia virus TB (MoMuLV-TB) ts1 mutant induces neurologic and immunologic disease in mice.
• The disease is characterized by spongiform encephalomyelopathy, hind-limb paralysis, thymic atrophy, immunodeficiency, and body wasting.
• T cells, particularly CD4+ helper T cells, are crucial in ts1 pathogenesis.

Purpose of the Study:

• To elucidate the cellular and molecular mechanisms of ts1 neuro- and immunopathogenicity.
• To investigate the role of the precursor envelope protein (gPr80env) in ts1-induced cytopathic effects.
• To assess the impact of ts1 infection on astrocytes and its potential indirect neuronal cell killing.

Main Methods:

• Analysis of the neuropathogenic determinant of ts1, mapping to a Val-25-Ile substitution in gPr80env.
• Assessment of gPr80env oligomerization and transport from the ER to the Golgi at restrictive temperatures.
• Establishment of primary astrocytic cultures to evaluate ts1 and MoMuLV-TB cytopathic effects and viral replication.
• Electron microscopy of ts1-infected astrocytes to identify aberrant particles.

Main Results:

• The Val-25-Ile substitution in gPr80env impairs its transport from the ER, potentially causing ER accumulation and cytopathic effects in neural cells.
• Both ts1 and MoMuLV-TB replicate in astrocytes, with ts1 exhibiting greater cytopathic effects.
• Processing of ts1 gPr80env in astrocytes is slower than MoMuLV-TB, correlating with ts1's cytopathic effect.
• Electron microscopy revealed aberrant particles in the ER of ts1-infected astrocytes.

Conclusions:

• Inefficient transport and processing of ts1 gPr80env correlate with its cytopathic effect in astrocytes.
• Accumulation of gPr80env oligomers in the ER may contribute to the cytopathic effect of ts1 in neural cells.
• An indirect mechanism of neuronal cell killing by ts1 is proposed, potentially initiated by astrocyte damage.