[Transmission of rabies virus: importance of the species barrier]

The authors describe experimental inoculations of different animal species with either the wild-type rabies virus or the modified one through in vivo or in vitro passages. With these experiments, it was possible to determine the 50% lethal dose of these viruses for these species, and to thus quantify the importance of the species barrier that opposes, in particular, the transmission of vulpine rabies to cats and dogs (respectively 10(5) and 10(6) times more resistant than foxes). Studies were also undertaken on the influence of the inoculation route and that of serial passages of the virus in vivo or in vitro on the importance of resistance to rabies. The epidemiological consequences of the existence of a species barrier, its nature and variability, are discussed.