Rabies as a transneuronal tracer of circuits in the central nervous system

The ability of selected neurotropic viruses to move transneuronally in the central nervous system makes them particularly well suited for use as trace rs in experimental neuroanatomy. Recently, techniques have been developed f or using rabies virus as a transneuronal tracer. Several features of rabies infection make the virus particularly useful for this purpose. We examined transneuronal transport of rabies in the central nervous system of primate s after intracortical and intramuscular injections. Rabies was transported in a time-dependent manner to infect synaptically-connected chains of neuro ns. Transport occurred exclusively in the retrograde direction. At the surv ival times we used, rabies infection was restricted to neurons and did not cause cell lysis. There are several methodological and safety issues that m ust be considered when designing studies that use rabies as a transneuronal tracer. When appropriate protocols and laboratory practices have been esta blished, transneuronal transport of rabies can be a safe and efficient tool for revealing the organization of multi-synaptic circuits in the central n ervous system. (C) 2000 Published by Elsevier Science B.V.