Rabies is a central nervous system disease that is almost constantly fatal. The causative agent is rabies virus a negative-stranded RNA virus of the rhabdovirus family. RV pathogenesis, like that of alternative viruses, is a multigenic trait. Recent findings indicate that in addition to the RV G protein viral elements that regulate gene expression, especially expression of the L gene, are also likely to play a role in RV pathogenesis. In vivo, RV infects almost exclusively neurons, and neuro invasiveness is the considerable defining characteristic of a classical RV infection.