The dissemination of rabies virus into cranial nerves and other tissues of experimentally infected goats and dogs and naturally infected skunks.

Immunofluorescence examination for rabies virus antigen performed on skin specimens acquired from experimentally inoculated rabid goats and some dogs, often show little or not fluorescence. This observation is contrary to results obtained by comparable examination of the skin of naturally infected animals and most experimentally infected dogs. In an effort to elucidate some factors associated with this experience, an experiment was performed to similarly examine the cranial nerves to see if the limited amounts of fluorescing antigen observed in the skin were also found there. Direct immunofluorescence examination for rabies virus antigen was therefore performed on cranial nerves, face, skin and other tissues excised from experimentally inoculated goats and dogs, and naturally infected skunks. We observed that the cranial nerves of those animals with limited fluorescence in nerves of the skin also contained only limited amounts of rabies virus antigen, while both the cranial and peripheral nerves of naturally infected skunks had large amounts of antigen. All the cranial nerves checked in the experimentally inoculated animals had virus antigen at points close to the brain. Limited fluorescence in the peripheral nerves of rabid animals has been associated with the short incubation period often experienced with experimentally inoculated animals, with the exception of the goat. The incubation period, in turn, is related to the degree of susceptibility of the new host, the quantity of virus, the route of infection, and the degree of adaptation of the virus to the new host.