Studies into immunisation of cattle against interdigital necrobacillosis

Area of Science:

• Veterinary immunology
• Bacterial pathogenesis

Background:

• Fusobacterium necrophorum causes interdigital necrobacillosis (foot abscess) in calves.
• Effective vaccines are crucial for preventing economic losses in cattle farming.

Purpose of the Study:

• To investigate the efficacy of Fusobacterium necrophorum fractions as a vaccine against experimental foot abscesses in calves.
• To identify the specific antigens responsible for inducing protective immunity.

Main Methods:

• Calves were immunized with F. necrophorum fractions in a mineral oil adjuvant.
• Experimental foot abscesses were induced via subcutaneous injection of homologous organisms.
• The challenge dose required to induce swelling in 50% of control calves was determined.

Main Results:

• Immunization with F. necrophorum fractions conferred immunity against experimental foot abscesses.
• A dose of approximately 2.2 x 10(8) cells from an 18-hour culture induced significant swelling in control calves.
• Immunity was associated with antigens present in the culture supernatant, possibly exotoxins.

Conclusions:

• Fractions of Fusobacterium necrophorum can induce protective immunity against foot abscesses in calves.
• Supernatant antigens, potentially exotoxins, play a key role in the observed immunity.