Degeneration of neuronal processes after infection with pathogenic, but not attenuated, rabies viruses.

The structural alterations of neuronal processes in mice were investigated after the mice were infected with rabies virus (RV). Silver staining of infected brain sections showed severe destruction and disorganization of neuronal processes in mice infected with pathogenic RV but not with attenuated RV. However, neuronal bodies showed very little pathological changes. Electron microscopy revealed the disappearance of intracellular organelles, as well as the disappearance of synaptic structures and vesicles. Infection of primary neurons with pathogenic, but not attenuated, RV resulted in the destruction of neuronal processes and disappearance of microtubule-associated protein 2 and neurofilament immunoreactivity, which suggests that pathogenic RV causes degeneration of neuronal processes possibly by interrupting cytoskeletal integrity.