Comparative Analysis of Antibodies Responses Induced by Three Commercial Foot-and-Mouth Disease Vaccines Against Three Virus Serotypes in Egyptian Cattle

Vaccination remains the main control practice for foot-and-mouth disease (FMD), particularly in endemic regions like Egypt, where three FMD virus (FMDV) serotypes (A, O, and SAT2) circulate. This study aimed to compare the immunogenicity of three commonly used FMD vaccines in Egypt by evaluating neutralizing antibody responses against three FMDV serotypes (A Iran 05, O Pan-Asia2, and SAT2 ERI) in beef cattle. Thirty-five unvaccinated calves were grouped and vaccinated with either locally produced vaccine A (oil-adjuvanted multivalent), locally produced vaccine B (oil-adjuvanted heptavalent), or imported vaccine C (aluminum hydroxide and saponin-adjuvanted hexavalent). Serum samples were collected at 0, 21, 56, 91, and 126 days post-vaccination (DPV) and tested using the serum neutralization test to determine serotype-specific log10 antibody titres. Baseline antibody levels at 0 DPV were below the protective threshold (log10 ≥ 1.5) for all groups. Vaccine A induced significantly lower antibody titres compared to vaccines B and C, with no significant changes in antibody titres across all time points, raising concerns about its efficacy. Vaccine B elicited sustained protective titres against all serotypes until 126 DPV. Vaccine C showed an initial protective response, but titres waned significantly below the protective threshold by 91 DPV. Additionally, Protective titre against SAT2 ERI was achieved following a booster dose of vaccine C. These findings highlight the superior performance of vaccine B in inducing durable and rapid protective immune responses, likely due to its oil-based adjuvant system. Both vaccines B and C are recommended for inclusion in vaccination campaigns, with selection depending on financial considerations since vaccine C requires revaccination within shorter intervals.