Preparation and evaluation of a monovalent foot and mouth disease vaccine as a rapid response to the emerging serotype SAT1 in Egypt.

The recent emergence of foot and mouth disease virus (FMDV) serotype SAT1 in Egypt necessitated the development of a specific vaccine directed against the newly introduced serotype. The present study describes the preparation and evaluation of a monovalent inactivated SAT1 vaccine with potential for inclusion in national FMD control programs. Three SAT1 field isolates were adapted in BHK-21 cells through serial passage, after which an optimal master seed virus was selected based on reproducible and stable infectivity characteristics. The vaccine was formulated as a double oil emulsion using Montanide ISA 206. The vaccine potency was assessed in guinea pigs through determination of the protective dose (GPPD50) following challenge with virulent guinea pig adapted virus that revealed satisfactory protective potency. The humoral immune response induced by such vaccine was subsequently evaluated in vaccinated cattle (2 mL dose), buffaloes (2 mL dose), and sheep (1 mL dose) through monitoring of their serum neutralizing antibody titers. Protective antibody levels were detected at 14 days in cattle and buffaloes and at 21 days in sheep post vaccination. The exhibited immunity had a duration extended to 32 weeks in cattle and buffaloes and to 28 weeks in sheep. These findings indicate that the prepared SAT1 vaccine was capable of inducing protective and sustained humoral immunity in the principal livestock species targeted within Egyptian vaccination campaigns and support its potential application in national FMD control programs.