[Experiments with vaccination against infectious epididymitis in rams]

Area of Science:

• Veterinary immunology
• Bacteriology

Context:

• Brucella ovis infection poses a significant threat to ram health and flock productivity.
• Vaccination strategies are crucial for controlling and eradicating Brucella ovis.
• Adjuvant choice impacts vaccine efficacy in preventing ovine brucellosis.

Purpose:

• To evaluate the efficacy of two killed Brucella ovis vaccines with different adjuvants (hydroxide vs. oil).
• To assess the level of acquired resistance in vaccinated rams following challenge with a virulent Brucella ovis strain.
• To determine the duration of postvaccinal antibodies and establish optimal vaccination protocols.

Summary:

• Two killed Brucella ovis vaccines, differentiated by hydroxide or oil adjuvants, were administered to rams twice. Vaccinated rams were challenged with virulent Brucella ovis, and immunity was assessed via serological tests (complement-fixation, hemagglutination, agar gel immunodiffusion) and clinical/bacteriological semen analysis.
• Rams receiving the oil-adjuvanted vaccine developed solid immunity against Brucella ovis challenge.
• Postvaccinal antibodies waned after three months, suggesting a need for booster vaccinations.

Impact:

• Oil-adjuvanted Brucella ovis vaccines provide robust protection, enabling the continued use of valuable infected animals without spreading infection.
• A 6-month vaccination schedule for infected flocks is proposed, alongside serological monitoring at three months post-vaccination for infected animal identification.
• This vaccination strategy aids in flock management and the gradual elimination of Brucella ovis infections.