Experimental rabies: ultrastructural quantitative analysis of the changes in the sciatic nerve

Area of Science:

• Neuroscience
• Virology
• Pathology

Background:

• Rabies is a fatal viral disease affecting the nervous system.
• Understanding peripheral nerve pathology in rabies is crucial for disease progression insights.

Purpose of the Study:

• To investigate the ultrastructural changes in peripheral nerves during experimental street rabies virus infection in mice.
• To correlate viral dose with the extent and type of axonal damage.

Main Methods:

• Street rabies virus was inoculated into the footpads of two groups of mice at different doses (10(4.5) LD50 and 10(3.5) LD50).
• Peripheral nerves (sciatic nerves) were examined using electron microscopy to assess axonal degeneration.
• Paralysis incidence and axonal diameter alterations were quantified.

Main Results:

• Significant degeneration of myelinated axons (approximately 40%) was observed in the sciatic nerves.
• Higher viral doses (Group A) resulted in more frequent paralysis (60%) and widespread axonal alterations across all sizes.
• Lower viral doses (Group B) showed a tendency to damage larger axons, with less paralysis (20%).
• Asymptomatic animals had minimal axonal necrosis (<1%).

Conclusions:

• Experimental rabies infection induces substantial peripheral nerve pathology, characterized by myelinated axonal degeneration.
• The severity of nerve damage and clinical signs correlates with the viral inoculum dose.
• Ultrastructural analysis revealed axonal degeneration as a key feature, though typical viral particles were not observed.