Rabies virus entry into endosomes in IMR-32 human neuroblastoma cells

Area of Science:

• Virology
• Cell Biology
• Neuroscience

Background:

• Rabies virus is a significant neurotropic pathogen.
• Understanding viral entry mechanisms is crucial for developing antiviral strategies.

Purpose of the Study:

• To investigate the early events of rabies virus entry into cultured IMR-32 human neuroblastoma cells.
• To elucidate the cellular compartments involved in rabies virus internalization and trafficking.

Main Methods:

• Immunofluorescence microscopy was used to localize rabies virus and cellular markers.
• Confocal microscopy and electron microscopy were employed to visualize virus-cell interactions.
• Acidotropic probes and specific tracers (e.g., Lucifer Yellow) identified endosomal compartments.

Main Results:

• Rabies virus rapidly colocalized with early endosomal markers and transferrin receptor after cell surface adsorption and warming.
• Virus particles were found within acidic endosomes, indicating fusion events.
• Rabies virus was also observed within synaptic vesicle markers in nerve terminals, suggesting entry into neuronal processes.
• Electron microscopy confirmed virus presence within membrane-bound compartments continuous with the cell membrane.

Conclusions:

• Rabies virus enters IMR-32 neuroblastoma cells through adsorptive endocytosis.
• The virus traffics to and fuses with acidic endosomes shortly after internalization.
• These findings provide insights into the initial steps of rabies virus neuroinvasion.