Evaluation of the Efficacy of Modified Vaccinia Ankara (MVA)/IMVAMUNE (registered trademark) Against Aerosolized Rabbitpox Virus in a Rabbit Model
ARMY MEDICAL RESEARCH INST OF INFECTIOUS DISEASES FORT DETRICK MD PATHOLOGY DIV
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Infection of rabbits with aerosolized rabbitpox virus RPXV produces a disease similar to monkeypox and smallpox in humans and provides a valuable, informative model system to test medical countermeasures against orthopoxviruses. Due to the eradication of smallpox, efficacy evaluation of new-generation smallpox vaccines depends on relevant well-developed animal efficacy studies for vaccine licensure. In this study, we tested the efficacy of IMVAMUNE Modified Vaccinia Virus Ankara-Bavarian Nordic MVA-BN for protecting rabbits against aerosolized RPXV. Rabbits were vaccinated with either phosphate-buffered saline PBS, Dryvax , a single low dose of IMVAMUNE , a single high dose of IMVAMUNE , or twice with a high dose of IMVAMUNE . Aerosol challenge with a lethal dose of RPXV was performed 4 weeks after the last vaccination. All PBS control animals succumbed to the disease or were euthanized because of the disease within 7 days postchallenge. The rabbits vaccinated with Dryvax , a low dose of IMVAMUNE , or a single high dose of IMVAMUNE showed minimal to moderate clinical signs of the disease, and all of them recovered. The only clinical sign displayed by rabbits that had been vaccinated twice with a high dose of IMVAMUNE was mild transient anorexia in just two animals. This study shows that IMVAMUNE can be a very effective vaccine against aerosolized RPXV.