Immunogenicity, Safety, and Anti-Viral Efficacy of a Subunit SARS-CoV-2 Vaccine Candidate in Captive Black-Footed Ferrets (<i>Mustela nigripes</i>) and Their Susceptibility to Viral Challenge
Ariel E. Leon,
Della Garelle,
Airn Hartwig,
Elizabeth A. Falendysz,
Hon S. Ip,
Julia S. Lankton,
Tyler N. Tretten,
Terry R. Spraker,
Richard Bowen,
Tonie E. Rocke
Affiliations
Ariel E. Leon
U.S. Geological Survey, National Wildlife Health Center, 6006 Schroeder Rd., Madison, WI 53711, USA
Della Garelle
U.S. Fish and Wildlife Service, National Black-Footed Ferret Conservation Center, 19180 North East Frontage Road, Carr, CO 80612, USA
Airn Hartwig
Department of Biomedical Sciences, Colorado State University, 3107 Rampart Road, Fort Collins, CO 80523, USA
Elizabeth A. Falendysz
U.S. Geological Survey, National Wildlife Health Center, 6006 Schroeder Rd., Madison, WI 53711, USA
Hon S. Ip
U.S. Geological Survey, National Wildlife Health Center, 6006 Schroeder Rd., Madison, WI 53711, USA
Julia S. Lankton
U.S. Geological Survey, National Wildlife Health Center, 6006 Schroeder Rd., Madison, WI 53711, USA
Tyler N. Tretten
U.S. Fish and Wildlife Service, National Black-Footed Ferret Conservation Center, 19180 North East Frontage Road, Carr, CO 80612, USA
Terry R. Spraker
Department of Microbiology, Immunology and Pathology, Colorado State University, 2450 Gillette Dr, Fort Collins, CO 80526, USA
Richard Bowen
Department of Biomedical Sciences, Colorado State University, 3107 Rampart Road, Fort Collins, CO 80523, USA
Tonie E. Rocke
U.S. Geological Survey, National Wildlife Health Center, 6006 Schroeder Rd., Madison, WI 53711, USA
A preliminary vaccination trial against the emergent pathogen, SARS-CoV-2, was completed in captive black-footed ferrets (Mustela nigripes; BFF) to assess safety, immunogenicity, and anti-viral efficacy. Vaccination and boosting of 15 BFF with purified SARS-CoV-2 S1 subunit protein produced a nearly 150-fold increase in mean antibody titers compared to pre-vaccination titers. Serum antibody responses were highest in young animals, but in all vaccinees, antibody response declined rapidly. Anti-viral activity from vaccinated and unvaccinated BFF was determined in vitro, as well as in vivo with a passive serum transfer study in mice. Transgenic mice that received BFF serum transfers and were subsequently challenged with SARS-CoV-2 had lung viral loads that negatively correlated (p < 0.05) with the BFF serum titer received. Lastly, an experimental challenge study in a small group of BFF was completed to test susceptibility to SARS-CoV-2. Despite viral replication and shedding in the upper respiratory tract for up to 7 days post-challenge, no clinical disease was observed in either vaccinated or naive animals. The lack of morbidity or mortality observed indicates SARS-CoV-2 is unlikely to affect wild BFF populations, but infected captive animals pose a potential risk, albeit low, for humans and other animals.
