Studies on development of early immunity against type O FMD in naturally susceptible animals

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FMD risk in the Russian Federation dictates the need for enhanced measures aiming to prevent the introduction of FMD virus and comprising systematic monitoring research and mass vaccination of susceptible animals in the buffer zone. Research into the development of vaccines for early protection confirm that their use induces the formation of virus-neutralizing antibodies in naturally susceptible animals in the outbreak area, which protects from FMD infection, limits its spread and contains it within the primary outbreak. Taking into account the high speed of the infection spread, such a control measure as using FMD vaccines which induce early protection should be adopted immediately after the occurrence of the outbreak. The article presents the results of the research into the formation of humoral immunity in naturally susceptible animals triggered by administration of inactivated emulsion FMD vaccines capable of ensuring early protection against type O FMD. Culture FMD virus of О/Primorsky/2012, О/Saudi Arabia/08 and О/Mongolia/2017 strains was used for vaccine production. Immunogenic activity of vaccines was tested in cattle, pigs, and sheep. It was found that monovalent emulsion FMD vaccine based on О/Mongolia/2017 strain induced the formation of virus-neutralizing antibodies in the quantity necessary to protect against the homologous strain in seven days after a single administration in the dose of 2 cm3 . Vaccines based on О/Saudi Arabia/08 and О/Primorsky/2012 FMDV strains can protect animals from infection with heterologous О/Mongolia/2017 strain at early stages if a double dose is administered. Vaccines based on the above-mentioned strains induce early immunity formation (seven days after vaccination) against type O FMD. We suggest using the given products in the zones of a higher risk of the virus introduction.