Interaction between rabies infection and oral administration of vaccinia-rabies recombinant virus to foxes (Vulpes vulpes).

We have investigated the influence of anti-rabies vaccination on the onset of the disease as well as the delay of death in foxes previously infected with rabies virus. A live vaccinia recombinant virus expressing the rabies virus glycoprotein (VVTGgRAB) was used as vaccine. Foxes were divided into six experimental groups of four animals. On day 0, each fox was experimentally infected with a rabies virus suspension. VVTGgRAB was administered by the oral route to each animal of three groups on day 0, 3 or 14. Foxes of other groups were used as unvaccinated controls or received, on day 0, the parental Copenhagen strain of vaccinia virus. The length of post-challenge survival and duration of clinical disease were recorded for each animal tested. All foxes, vaccinated or not, died from rabies as confirmed by fluorescent antibody tests. Animals vaccinated on days 0 and 3 died after a shorter period of incubation than unvaccinated controls. On the other hand, animals vaccinated on day 14 post-challenge died later than control animals. Foxes administered vaccinia virus died at the same time as unvaccinated controls. These results demonstrate that early and late death phenomena, as consequences of interactions between oral vaccination with VVTGgRAB and rabies infection, can occur in foxes.