Protective vaccination of ferrets against canine distemper with recombinant pox virus vaccines expressing the H or F genes of rinderpest virus

Objective-To investigate the ability of rinderpest virus (RPV) antigens, expressed in pox virus vectors, to protect against canine distemper virus (CDV) infection in ferrets. Animals-Ferrets (Mustela putorius; n = 27) with no previous exposure to CDV. Procedure-Ferrets were inoculated intradermally with recombinant vaccinia viruses expressing the H gene of RPV, the F gene of RPV, the H and F genes of RPV, or a fowlpox virus recombinant expressing both genes. Two ferrets were vaccinated SC with CDV vaccine as positive controls, and 1 group was left unvaccinated as a negative control. Blood was obtained from ferrets biweekly; antibody titer to RPV was detected by ELISA, and CDV antibody titer was measured by serum neutralization testing and ELISA. Results-Partial protection was seen in all groups, with vRVFH vaccination being the most protective (60%). Conclusions and Clinical Relevance-A single inoculation with a vaccinia virus expressing the H and F genes of RPV was able to protect 60% of the vaccinated ferrets challenge exposed with a high dose of CDV. These results indicate the ability of RPV antigens expressed by vaccinia virus to protect ferrets against a related morbillivirus. Further, they document the safety and efficacy of a recombinant vaccinia virus vaccine for ferrets. Such vaccines may be useful given the susceptibility of ferrets to CDV and the problem of maternal antibody interfering with vaccination of young animals.