Long-Term Immunogenicity and Efficacy of the Oral Rabies Virus Vaccine Strain SPBN GASGAS in Foxes

• Main Authors: Conrad M. Freuling, Verena te Kamp, Antonia Klein, Maria Günther, Luca Zaeck, Madlin Potratz, Elisa Eggerbauer, Katharina Bobe, Christian Kaiser, Antje Kretzschmar, Steffen Ortmann, Peter Schuster, Adriaan Vos, Stefan Finke, Thomas Müller
• Format: Article
• Language: English
• Published: MDPI AG 2019-08-01
• Series: Viruses
• Subjects: oral rabies vaccines; rabies; genetically engineered vaccine; red foxes; efficacy; long-term immunogenicity; SPBN GASGAGS
• Online Access: https://www.mdpi.com/1999-4915/11/9/790

To evaluate the long-term immunogenicity of the live-attenuated, oral rabies vaccine SPBN GASGAS in a full good clinical practice (GCP) compliant study, forty-six (46) healthy, seronegative red foxes (<i>Vulpes vulpes</i>) were allocated to two treatment groups: group 1 (<i>n</i> = 31) received a vaccine bait containing 1.7 ml of the vaccine of minimum potency (10^6.6 FFU/mL) and group 2 (<i>n</i> = 15) received a placebo-bait. In total, 29 animals of group 1 and 14 animals of group 2 were challenged at 12 months post-vaccination with a fox rabies virus isolate (10^3.0 MICLD₅₀/mL). While 90% of the animals offered a vaccine bait resisted the challenge, only one animal (7%) of the controls survived. All animals that had seroconverted following vaccination survived the challenge infection at 12 months post-vaccination. Rabies specific antibodies could be detected as early as 14 days post-vaccination. Based on the kinetics of the antibody response to SPBN GASGAS as measured in ELISA and RFFIT, the animals maintained stable antibody titres during the 12-month pre-challenge observation period at a high level. The results indicate that successful vaccination using the oral route with this new rabies virus vaccine strain confers long-term duration of immunity beyond one year, meeting the same requirements as for licensure as laid down by the European Pharmacopoeia.