The primary multiplication site of VVTGgRAB, a recombinant vaccinia virus (VV) expressing the rabies virus G glycoprotein, was studied in comparison with that of the parental VV Copenhagen strain, after oral administration to foxes. Foxes were fed with 10(8) TCID50 of either VVTGgRAB or VV and were sacrificed 12, 24, 48 or 96 h after inoculation. Both viruses were detected by viral isolation in the tonsils during the first 48 h after inoculation at titres between 10(2) and 10(4.3) TCID50/ml. Indirect immunofluorescence confirmed the presence of the virus in tonsils of some of the foxes. The polymerase chain reaction allowed the detection of VVTGgRAB in the tonsils of both of two foxes tested after 24 h, three of three foxes after 48 h, in the buccal mucosa of one of two foxes tested after 24 h and two of three foxes after 48 h and in the soft palate of one of two foxes tested after 24 h and one of three foxes after 48 h. VV was detected in the tonsils of one fox tested after 48 h, in the buccal mucosa of another fox tested after 24 h, and in the first fox after 48 h by the same reaction. Foxes were inoculated with virus isolated from fox tonsils 24 h after oral administration (with or without cell culture amplification) to perform back passages. No virus could be isolated in either case after this passage. The innocuity of VVTGgRAB was also demonstrated when foxes were inoculated with passaged virus.