Results of the development of a vaccine against strangles in horses for Russia and Mongolia

Equine strangles, a widespread infectious disease, poses a serious problem resulting in significant economic losses in the horse breeding industry. As there are no effective and safe methods for specific prevention of this disease in Russia and Mongolia, a new inactivated vaccine against strangles, incorporating an immunostimulating component, has been developed. Unlike foreign analogues containing broad-spectrum antibiotics, the developed vaccine is characterized by the absence of harmful side effects, as confirmed by preclinical and clinical trials on laboratory and target animals (foals), demonstrating high efficacy and safety. As the result of the study of the vaccine high toxicity via intragastric administration at the maximum permissible volume (1 cm³) in white laboratory mice there was established the absence of pronounced toxic effects of the tested preparation on the laboratory animals. By the end of the observation period (7 days), the body weight of animals in the experimental group had increased by 0.6 g, and by 0.5 g in the control group. The vaccine pyrogenicity was studied in White Giant breed rabbits by intravenous injection into the ear vein at a dose of 0.1 cm³, with the control group rabbits receiving an equivalent dose of physiological saline. A comparative assessment of body temperature indicators in both rabbit groups revealed no statistically significant differences confirming the apyrogenicity of the product under study. High immunogenicity of the vaccine was established in white mice. A single subcutaneous injection of a 4×10⁸ CFU/mL dose of the vaccine provided 90 % immunity against the causative agent of strangles, with 90 % mortality observed in unvaccinated control animals. The immunizing dose (ID) for a single intramuscular administration was determined to be 4×10⁸ CFU/mL, providing an 80 % protection level. The vaccine has successfully undergone approval procedures and is authorized for use in the Russian Federation and Mongolia. This development product represents a significant advance in veterinary immunoprophylaxis offering a safe and effective alternative to the current vaccines against equine strangles.