Elimination of fox rabies from Belgium using a recombinant vaccinia-rabies vaccine: an update

Abstract

To improve both safety and stability of the vaccines used in the field to vaccinate foxes against rabies by the oral route, a recombinant vaccinia virus, expressing the glycoprotein of rabies virus (VVTGgRAB) has been developed. VVTGgRAB innocuity was verified in target species and in domestic animals as well as in numerous wild animal species that could compete with the red fox in consuming vaccine baits in Europe. Oral immunization of foxes, by distributing VVTGgRAB vaccine-baits, was undertaken in the whole of the infected area of Belgium (10,000 km2). Five campaigns of fox vaccination covering the whole infected area were carried out from the autumn of 1989 until 1991. Each time, 150,000 vaccine-baits were dispersed by air at a mean density of 15 per km2. These campaigns induced a drastic decrease in the incidence of rabies and the elimination of the disease from 80% of the initial infected area. Regarding the geographical evolution of rabies in Belgium and in adjacent regions in neighbouring countries, new spatial strategies for bait dispersal were planned for 1992, 1993 and 1994: successive restricted campaigns were carried out along political borders only. These campaigns induced a new decrease of incidence; no rabid foxes could be detected in 1993 in spite of an improved epidemiological surveillance. In 1994, rabies was confirmed again in 13 foxes collected in a region situated close to the French border. These cases demonstrate the persistence of a focus of rabies on the border and justify further restricted campaigns of vaccination.

Genetically engineered poxviruses for recombinant gene expression, vaccination, and safety.

“…Raccoon poxvirus (156) (160,161), chickens against influenza virus (162), and raccoons and foxes against rabies virus (163)(164)(165)(166). The recombinant vaccinia virus expressing the rabies virus glycoprotein was administered in bait form for immunization of wild animals and protective immunization with reduced incidence of rabies has been demonstrated in large field tests in Belgium (167). Examples of the use of other poxvirus vectors for veterinary purposes include a raccoon poxvirus vector to protect raccoons against rabies virus (156); a capripoxvirus vector to protect cattle against rinderpest (168); swinepox vectors to protect pigs against Aujeszky disease (pseudorabies) (158); fowlpox vectors to protect chickens against influenza virus (169), Newcastle disease virus (152,(170)(171)(172), and infectious bursal disease virus (173); canarypox virus to protect dogs against canine distemper virus (154); and pigeonpox virus vectors to protect chickens against Newcastle disease virus (174).…”

New Strategies for Immune-Mediated Anti-Viral Drug and Vaccine Development

“…This might change, as more veterinary rVV-based vaccines prove safe, and are implemented. Many such vaccines were shown to protect animals against several viral disease like VSV [79] and rinderpest virus in cattle [80], rabies in dogs [81], and in wild animals [82][83][84], influenza in chickens [85], and pseudorabies in pigs [86]. Several other species-specific poxyvirus-based vaccines were also found efficacious such as rabies in raccoons [87] and influenza and Newcastle disease in chickens [88,89].…”

A Baiting System for Delivery of an Oral Plague Vaccine to Black-Tailed Prairie Dogs

“…Recent studies have evaluated the effectiveness of an insect growth regulator for flea control as an alternative to insecticides (Karhu, 1999). Advances in vaccine development have resulted in safe and efficacious vaccines that can be used for controlling diseases in wildlife, such as rabies (Rupprecht et al, 1986;Brochier et al, 1995), and the National Wildlife Health Center (NWHC; Madison, Wisconsin, USA) is currently conducting laboratory studies to evaluate the efficacy of oral plague vaccines for prairie dogs.…”

“…Bait designs and vaccine distribution methods have been reported for a variety of species including red foxes (Vulpes vulpes) in Europe (Brochier et al, 1995) and Canada (Bachmann et al, 1990), raccoons (Procyon lotor) (Hable et al, 1991), and mongooses (Herpestes javanicus) (Creekmore et al, 1994). Biomarkers such as tetracycline (Linhart and Kennelly, 1967), iophenoxic acid (Fletcher et al, 1990), or DuPont Blue dye (Creekmore et al, 1994) are normally incorporated into the baits to evaluate the success of bait distribution studies or to identify animals that have consumed a vaccine-laden bait.…”