Bacterial Vaccines

Vaccine Mechanism

• Primary and Secondary Immune Response

  • B cells:

    • Upon 1st exposure to an antigen, activated B cells proliferate.

    • Some B cells become Memory B cells, which help speed up future responses to the same antigen.

  • Plasma Cells:

    • Produce antibodies specific to the antigen upon activation.

How Vaccines Work

1. Introduction of Antigen:

   • Antigen is introduced into the body through vaccination.

2. Antibody Production:

   • The immune response activates and produces antibodies.

3. Preparedness for Natural Exposure:

   • If the horse encounters the actual pathogen later, pre-existing antibodies will combat it effectively.

Vaccine Benefits

• Disease Prevention:

  • Vaccines significantly reduce the risk of dangerous infections.

  • They work by assisting the body's natural defenses, ensuring the development of immunity.

• Immune System Stimulation:

  • Vaccines nearly never cause illness but stimulate the production of T-lymphocytes and antibodies.

  • They provide beneficial memory cells for long-term immunity.

Types of Antibodies (Immunoglobulins)

• IgM: Main antibody for primary responses, important for fixing complement.

• IgG: Primary antibody for secondary responses; critical for phagocyte binding.

• IgA: Found in mucosal areas such as saliva and tears; tags pathogens for destruction.

• IgD: Functions mainly as a B-cell receptor; stimulates IgM release.

• IgE: Involved in allergic reactions and antiparasitic activity; binds to basophils and mast cells.

Antibody Concentration Dynamics

• Primary Response:

  • Initial antibody response is dominated by IgM; later shifts to IgG.

  • Time frame: 10 to 20 days post-exposure for antibody production.

• Secondary Response:

  • Rapid increase in IgG due to the presence of memory cells, indicating a quicker response.

Immunoglobulin Importance

• IgA:

  • Found in mucous membranes and fluids such as saliva and breastmilk. Important for mucosal immunity.

Goals of Vaccination in Animals

• Companion Animals:

  • To ensure health and welfare.

• Livestock:

  • Improve overall production and reduce zoonotic disease risk.

• Wildlife:

  • Manage zoonotic diseases and preserve species.

Types of Vaccines

• Adjuvant:

  • Substance added to enhance the immune response to vaccines.

• Live Attenuated Vaccines:

  • Weakened pathogens stimulate strong immune responses with lower risks.

• Inactivated Vaccines:

  • Non-live pathogens provide safer alternatives but may require boosters.

• Toxoid Vaccines:

  • Inactivated toxins induce immunity against toxins produced by pathogens.

• Subunit Vaccines:

  • Focus on specific parts of the pathogen to elicit immune response.

• Conjugate Vaccines:

  • Combine polysaccharides (weak antigens) with proteins (strong antigens) for enhanced immune response.

Vaccine Administration Routes

• Nasal Mucosa:

  • High vascularization makes it effective; avoids injection-related issues.

• Intramuscular (IM) and Subcutaneous (SC):

  • Suitable traditional routes with various local side effects and immune response features.

Bacterial Vaccine Examples

• Vaccines for various target pathogens available through various distributors (Boehringer-Ingelheim, Pfizer, etc.).

• Specific vaccines labeled for animals such as pigs, dogs, fish, horses, and chickens targeting bacteria like Lawsonia intracellularis, Bordetella spp., Salmonella, etc.

Bordetella bronchiseptica

• Characteristics:

  • Colonizes the respiratory tract of dogs causing conditions like kennel cough. Commonly vaccinated against due to infection risk to cats.

• Vaccine Options:

  • Intranasal (IN) or parenteral (SC) with rapid immunity onset and prolonged effects.

Factors Affecting Vaccine Efficacy

• Animal-Related Factors:

  • Conditions that can impact immune response include immunosuppression, genetic influences, and heavy exposure to pathogens.

• Vaccine-Related Factors:

  • Include storage conditions, expiration, and reconstitution practices affecting vaccine potency and effectiveness.

Conclusion

• Importance of understanding and studying bacterial vaccines for effective immunization in veterinary practices.