In tissue culture systems most of these viruses can infect many types of cells, in addition to neurons. Few neuron-specific virus receptors have been identified (e.g., p75NTR, NCAM, and AChR for rabies; nectin for HSV) but these do not always account for neuronotropism in vivo [11] [12] [13] . Recent studies with HSV suggest that receptors used to enter processes of peripheral neurons can be different from those used to infect neurons in the brain [12] . Therefore, the mechanisms by which encephalitic viruses target neurons to the exclusion of other cells within the CNS are poorly understood. Once within the nervous system, encephalitic viruses often follow synaptic pathways for spread to other neuronal populations. These viruses interact with motor proteins either directly or through accessory proteins to travel using both anterograde (kinesin motors) and retrograde (dynein-dynactin motors) neuronal microtubule transport systems [6] .