BACTERIAL VACCINES AND CLINICAL CASES

• Vaccines


  • Prevent diseases that can be dangerous or deadly
  • Greatly reduce the risk of infection by working with the body's natural defenses to safely develop immunity to disease

  
• How vaccines work


  1. Imitating an infection

  2. Almost never cause illness

  3. Stimulate immune system to produce T-lymphocytes and antibodies

  4. Supply of "memory" T-lymphocytes and B-lymphocytes

  
• IgA


  Immunoglobulin found in mucous membranes, mainly in the respiratory and digestive tracts, also found in saliva, tears, and breastmilk

  
• Goals of vaccination of animals

  • Health and welfare of the individual animal (companion animals)
  • Improve overall production (livestock)
  • Eliminating risk for the consumer (zoonotic or food-borne infections) (livestock)
  • Improve productivity of the individual animal (livestock)
  • Zoonotic diseases (wildlife)
  • Preservation/protection (wildlife)

  
• Types of vaccines


  • Live, attenuated vaccines
  • Inactivated vaccines
  • Toxoid vaccines
  • Subunit vaccines
  • Conjugate vaccines

  
• Adjuvant


  Substance added to a vaccine to stimulate and enhance the magnitude and durability of the immune response

  
• Live, attenuated vaccines


  • Contain a weakened version of the pathogen
  • Induce both cellular and humoral immunity
  • Risk of reversion to virulence

  
• Inactivated vaccines


  • Contain inactivated (non-live) pathogen
  • Good safety profiles, less expensive
  • No effective long-term protection, new vaccines required from new outbreaks

  
• Toxoid vaccines


  • Contain inactivated native toxins combined with adjuvants
  • Diseases caused by bacterial toxins
  • Amount of toxin produced in vitro is unpredictable, high level of biosafety needed

  
• Subunit vaccines


  • Contain part of the target pathogen (essential antigens)
  • No risk for pathogenicity, well-defined composition, cost-efficient, primarily humoral immune response
  • Needs always adjuvant

  
• Conjugate vaccines


  • Connect polysaccharides (weak Ag) to carrier protein (strong Ag)
  • Increased immune response, both humoral and cell-mediated immune response, not always required adjuvant

  
• Bordetella bronchiseptica


  • Gram-negative bacterium colonizing the respiratory tract
  • Dogs: Tracheobronchitis, Kennel Cough -> shedding in oral and nasal secretions -> infection risk for cats
  • Core vaccination in dogs, not routinely in cats since the infection generally causes only a mild disease

  
• Bordetella bronchiseptica vaccines


  • Intranasal vaccine: modified-live vaccine
  • Parenteral vaccine: killed cellular antigen extract

  
• Intranasal (IN) Bordetella vaccine


  • Only 1 dose required (versus 2 SC doses)
  • Induces both mucosal and systemic immunity, rapid onset of immunity
  • Not affected by maternal antibodies (ideal for young puppies)
  • Immunity lasts for 12 months
  • Can be combined with parainfluenza and/or adenovirus-2 (SC only in monovalent form)

  
• There is NO vaccine for Bordetella that provides "full immunity", but vaccination still provides protection and exposed vaccinated dogs are expected to develop milder clinical signs if they do become infected

  
• Efficacy of vaccines is determined by many factors

  
• Vaccination Failure can potentially occur