[Safety and efficacy of an antirabies vaccine consisting of recombinant vaccinia-rabies virus administered orally to the fox, dog and cat]

Abstract

One of the most promising ways to control rabies in wildlife seems to be the distribution of bait containing an anti-rabies vaccine. So far, the most widely used vaccines were modified live viruses (SAD strain or derivatives). Nevertheless, these strains retain some pathogenicity for non-target species. A novel vaccine was proposed consisting of genetically modified vaccinia virus (strain Copenhagen, thermosensitive ts 26) expressing the foreign glycoprotein G for the rabies virus (strain ERA). Different doses of this recombinant virus were administered orally to 59 foxes (Vulpes vulpes) and their antibodies were titrated before challenge. Foxes (8/8) resisted 1 month after vaccination with 10(7) plaque forming units (PFU), or 4/4 after 18 months. Seroconversion among dogs was 4/4 after vaccination with 10(9,6) PFU and 4/4 among cats after vaccination with 10(8) PFU. These dogs (4/4) and cats (3/4) resisted the challenge 2-3 months after vaccination. This vaccine thus appears to be potent and safe in these species. Its properties are discussed.