Development of a Serogroup B Specific Footrot Vaccine with Montanide ISA 61 VG Adjuvant for Prophylactic and Therapeutic Use in Sheep

Virulent footrot represents as a significant contagious ailment affecting sheep, with Dichelobacter nodosus being the primary agent responsible for transmitting the disease. Vaccinations and various management practices are utilized to control the disease. In this study, we cultured D. nodosus in broth culture under reducing conditions and formulated a vaccine using Montanide oil as adjuvant. The efficacy of the vaccine was assessed in sheep to determine its ability to elicit an effective immune response and its therapeutic potential. D. nodosus serogroup B (JKS-07B strain) was grown in a modified TAS broth and a whole cell killed vaccine was prepared using 1.5 × 109 cells per dose, along with the oil adjuvant Montanide ISA 61 VG. The vaccine trial was conducted in sheep and two doses of the vaccine were given subcutaneously with a 30 days interval between the doses. The serum antibody titers in the vaccinated animals were measured at 0, 30, 60, 90, 120, and 150 days post-vaccination using the microplate agglutination test. Protective antibody titers (≥ 3000) were achieved by the 30th day following the primary vaccination in all animals, reaching their peak at the 60th day. The protective level of antibody titers was maintained up to 120 days following the primary vaccination. The vaccine also demonstrated a therapeutic effect in animals that were clinically affected. Animals with a lesion score of 2 took 18-21 days for recovery, while those with a lesion score of 3-4 took 40-47 days to recover from lameness.