Assessing immune competence in pigs by immunization with tetanus toxoid

Area of Science:

• Veterinary Immunology
• Swine Health
• Vaccinology

Background:

• Assessing immune competence in domestic pigs is crucial but challenging due to disease control restrictions.
• Vaccination-induced immune responses offer a viable alternative for evaluating immune competence.
• Tetanus toxoid (TT) vaccination was explored as a model to assess immune responses in developing pig immune systems.

Purpose of the Study:

• To optimize a vaccination protocol using tetanus toxoid (TT) for assessing immune competence in young pigs.
• To determine the optimal timing for primary and booster immunizations and blood sampling for maximal TT-specific immune responses.
• To evaluate the influence of age on TT-specific immune responses and general immune parameters.

Main Methods:

• Young pigs were immunized with a commercial TT vaccine at 21 or 35 days of age, with booster immunizations at 14 or 21 days post-primary.
• TT-specific antibody levels were measured using ELISA, and lymphoproliferative responses were assessed via lymphocyte transformation tests.
• General IgG, IgM, and mitogen-induced proliferation were also measured to provide a broader immune context.

Main Results:

• The highest TT-specific antibody and lymphoproliferative responses were detected 7 days after a booster immunization given 21 days after primary immunization.
• The age of primary immunization (21 vs. 35 days) did not significantly impact TT-specific immune responses.
• While general IgG and IgM levels were age-dependent, TT-specific responses and mitogen-induced proliferation were not significantly affected by age or sampling time.

Conclusions:

• A TT vaccination model provides a reliable method for assessing immune competence in young pigs, even with developing immune systems.
• The optimized vaccination and sampling protocol (booster 21 days post-primary, sample 7 days post-booster) yields robust TT-specific immune responses.
• This approach is valuable for swine health research, offering a non-infectious method to evaluate immune status without age-related bias in TT-specific responses.