Faculty of Natural and Agricultural Sciences
School of Biological Sciences
Department of Microbiology and Plant Pathology
Lyssavirus vaccines
Oral vaccination of free-roaming and feral dogs will be a major step in the struggle to control rabies in Africa. Despite the effective use of oral vaccines to vaccinate wildlife in Europe and Northern America, current oral vaccines (designed for wildlife - attenuated or classic poxvirus recombinant) are not appropriate for application in sub-Saharan Africa. The main problems are relative instability of some vaccines, or the potential danger of others, given the very high incidence of immunodeficiency in the resident human populations, primarily through the AIDS pandemic in the subcontinent. For various related reasons, the use of these classic pox recombinants has also been met with increasing resistance in the developed world. In this regard, a replication-deficient recombinant poxvirus expressing the relevant antigens may provide not only an effective vaccine but also a safer alternative to the currently available recombinant oral vaccines. Several such candidate vaccines (based on recombinant LSDV and MVA) have been constructed and evaluated in rodent and canine laboratory models. In addition, the generation of lyssavirus vaccines with an expanded range of effectiveness is a worthwhile objective. Combined or cross-reactive vaccines would be of obvious specific benefit to laboratory diagnosticians worldwide and to high-risk groups in those areas where nonrabies lyssaviruses are endemic. We have studied the cross-protective and cross-reactive responses elicited by DNA vaccines and recombinant vaccinia viruses expressing rabies, Mokola and/or West Caucasian bat virus glycoprotein genes either in single or in dual combinations. Our evidence suggest that a recombinant vaccine expressing rabies and Mokola virus glycoprotein is most likely to protect against the spectrum of lyssaviruses, but excluding West Caucasian bat virus (of which only a single bat isolate is known).
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