Vaccination with F1-V Fusion Protein Protects Black-Footed Ferrets (Mustela Nigripes) Against Plague Upon Oral Challenge with Yersinia Pestis

Earlier studies established that vaccination of black-footed ferrets (Mustela nigripes) with F1-V fusion protein by subcutaneous (SC) injection protected animals against plague upon injection of the bacterium Yersinia pestis. This study demonstrates that the F1-V antigen can also protect ferrets against plague contracted via ingestion of a Y. pestis-infected mouse, a probable route for natural infection. Eight black-footed ferret kits were vaccinated with F1-V protein by SC injection at approximately 60 days-of-age. A booster vaccination was administered 3 mo later via SC injection. Four additional ferret kits received placebos. The animals were challenged 6 wk after the boost by feeding each one a Y. pestis-infected mouse. All eight vaccinates survived challenge, while the four controls succumbed to plague within 3 days after exposure. To determine the duration of antibody post-vaccination, 18 additional black-footed ferret kits were vaccinated and boosted with F1-V by SC injection at 60 and 120 days-of-age. High titers to both F1 and V (mean reciprocal titers of 18,552 and 99,862 respectively) were found in all vaccinates up to 2-yr post-vaccination, whereas seven control animals remained antibody negative throughout the same time period. Pub. in Journal of Wildlife Diseases, v44 n1, p1-7. 2008.