HYPERSENSITIVENESS AND ANTIBODY FORMATION IN TUBERCULOUS RABBITS

Area of Science:

• Immunology
• Veterinary Medicine
• Microbiology

Background:

• Bovine tuberculosis is a significant zoonotic disease caused by Mycobacterium bovis.
• Understanding the immune response in infected animals is crucial for diagnosis and control.
• Tuberculin skin testing is a common diagnostic method, but its reliability can be affected by immune status.

Purpose of the Study:

• To investigate the dynamics of hypersensitivity and antibody production in rabbits infected with bovine tubercle bacilli.
• To correlate skin test reactivity with the presence of complement-fixing antibodies during the course of infection.
• To elucidate the immunological changes preceding death in rabbits with bovine tuberculosis.

Main Methods:

• Rabbits were infected with bovine tubercle bacilli.
• Intracutaneous tuberculin testing was performed to assess hypersensitivity.
• Serum samples were analyzed for the presence of complement-fixing antibodies against tubercle bacilli.

Main Results:

• Infection led to hypersensitivity to tuberculin, appearing between 2-6 weeks post-infection and increasing thereafter.
• Skin test sensitivity fluctuated and was eventually lost in the weeks preceding death.
• Complement-fixing antibodies appeared after 2 weeks, peaked between 6-10 weeks, and persisted until death.
• In late infection stages, rabbits showed a lack of skin reactivity despite the presence of complement-fixing antibodies in serum.

Conclusions:

• Rabbits infected with bovine tubercle bacilli exhibit a complex immune response characterized by initial hypersensitivity followed by anergy.
• The development of complement-fixing antibodies correlates with disease progression but does not guarantee skin test reactivity.
• These findings highlight the limitations of relying solely on skin testing for diagnosing advanced bovine tuberculosis and suggest further investigation into immune evasion mechanisms.