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    21. vaccines 21. vaccines Presentation Transcript

    • Chapter 21 Vaccines Copyright © 2011 Delmar, Cengage Learning
    • Immunity
      • Nonspecific immunity
        • Includes things such as physical barriers, mucus production, inflammation, fever, and phagocytosis
        • Directed against all pathogens; is the initial defense against invading agents
      • Specific immunity
        • Takes over when the nonspecific mechanisms fail
        • Targeted for a specific antigen; has memory
        • Arises from B- and T-lymphocytes
      Copyright © 2011 Delmar, Cengage Learning
    • Types of Immunity
      • Cell-mediated immunity
        • T-lymphocytes directly attack the invading antigen
        • Important for protecting against intracellular bacterial or viral infections, fungal diseases, and protozoal diseases
      • Antibody-mediated immunity
        • B-lymphocytes produce antibodies that react to antigen
        • Important for extracellular phases of systemic viral and bacterial infections and protection against endotoxin and exotoxin-induced disease
      Copyright © 2011 Delmar, Cengage Learning
    • Ways to Acquire Specific Immunity
      • Active immunity
        • Arises when an animal receives an antigen that activates B- and T-lymphocytes
        • Creates memory
      • Passive immunity
        • Arises when an animal receives antibodies from another animal
        • Provides immediate onset of immunity, but the animal is protected for a shorter time (no memory)
      • Natural immunity
        • Acquired during normal biological experiences
      • Artificial immunity
        • Acquired through medical procedures
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccines
      • A vaccine is a suspension of weakened, live, or killed microorganisms administered to prevent, improve, or treat an infectious disease
      • Types of vaccines:
        • Inactivated (killed): made from microbes, microbe parts, or microbe by-products that have been chemically treated or heated to kill the microbe
          • Contain adjuvants (substances that enhance the immune response by increasing the stability of the vaccine in the body); may cause vaccine reactions
          • Advantages: safe; stable; unlikely to cause disease
          • Disadvantages: need repeated doses; possible reactions
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccines
      • Types of vaccines (cont.):
        • Attenuated (modified-live): microorganisms go through a process of losing their virulence (called attenuation ), but must be able to replicate within the patient to provide immunity
          • Advantages: immunity lasts longer; has better efficacy and quicker stimulation of cell-mediated immunity than killed vaccines
          • Disadvantages: possible abortion; can produce mild forms of the disease; can shed into the environment; proper handling/storage is critical
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccines
      • Types of vaccines (cont.):
        • Live: made from live microorganisms that may be fully virulent
          • Advantages: fewer doses needed; last longer; inexpensive; adjuvants not needed
          • Disadvantages: residual virulence that requires carefully handling
        • Recombinant: a gene or part of a microorganism is removed from one organism (usually the pathogen) and inserted into another microorganism
          • Advantages: fewer side effects; effective immunity; varied routes of administration
          • Disadvantage: increased cost
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccines
      • Types of vaccines (cont.):
        • Adjuvants: substances that enhance the immune response
        • There are four types of adjuvants:
          • Depot
          • Particulate
          • Immunostimulatory
          • Mixed
        • Depot adjuvants protect antigens from rapid degradation which contributes to a prolonged immune response
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccines
      • Types of vaccines (cont.):
        • Particulate adjuvants deliver antigen in such a way that both cell-mediated and humoral immunity are enhanced by stimulation of antigen processing
        • Immunostimulatory adjuvants promote cytokine production
        • Mixed adjuvants combine a particulate or depot adjuvant with an immunostimulatory agent
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccines
      • Types of vaccines (cont.):
        • Polyneucleotides: or DNA vaccines injects DNA that encodes for foreign antigens is another type of vaccine
          • Advantage: that it is possible to select only the genes for the antigen of interest
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccines
      • Types of vaccines (cont.):
        • Toxoids: “vaccine” used against a toxin that has been deactivated by heat or chemicals, but is still able to stimulate antibody production
          • Advantage: provides protection against toxin
          • Disadvantages: shorter duration of effectiveness; may contain adjuvants
        • Antitoxins: substances that contain antibodies obtained from an animal that has been hypersensitized to neutralize toxins
          • Advantage: quick protection against a toxin
          • Disadvantages: short-lived protection; may contain preservatives that can cause reactions
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccines
      • Types of vaccines (cont.):
        • Antiserum: antibody-rich serum obtained from a hypersensitized or actually infected animal
          • Advantage: provides quick protection against a microorganism
          • Disadvantages: shorter duration of effectiveness; may contain adjuvants
        • Autogenous: vaccine produced for a specific disease in a specific area from a sick animal
          • Advantage: provides protection against the specific organism in a specific area
          • Disadvantage: may contain endotoxin and other by-products found in the culture
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccines
      • Types of vaccines (cont.):
        • Multiple-antigen vaccines are called polyvalent
        • Polyvalent vaccines contain more than one antigen
          • Contain a mixture of different antigens and are more convenient to administer because fewer injections are needed
          • Adverse reaction increases as the number of antigens increases
        • To be approved, must show that each part of the polyvalent vaccine induces the same level of immunity as does the single-antigen vaccine
        • Monovalent vaccines are vaccines with only a single antigen present
          • Using several monovalent vaccines may expose the animal to higher levels of adjuvants
          • Must give more injections
      Copyright © 2011 Delmar, Cengage Learning
    • Maternally Derived Antibodies
      • Maternally derived antibodies are antibodies that offspring receive passively from their mothers, either from colostrum or via the placenta
      • Maternally derived antibodies give the offspring disease resistance for a few days and provide variable antibody levels for up to nine weeks
      • To enhance this protection, young animals receive vaccinations and booster vaccinations to ensure appropriate immunity
        • Booster vaccines are needed because effective vaccination varies among individuals, because of variable levels of maternal antibodies
        • Booster vaccines also allow antibody levels to rise to satisfactory levels
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccine Reactions
      • Although vaccines are considered safe, vaccine reactions can occur
      • All vaccine reactions must be recorded in the medical record
      • Typical vaccine reactions:
        • Location reactions at the injection site
        • Fever
        • Lethargy
        • Vomiting
        • Salivation
        • Difficulty breathing
        • Vaccine-associated sarcomas in cats
        • Autoimmune hemolytic anemia in dogs
      Copyright © 2011 Delmar, Cengage Learning
    • Issues in Vaccine Use
      • Consider the following with all vaccine protocols:
        • Vaccine issues
          • Proper care and handling
          • Proper route of administration
          • Proper use (do not mix vaccine products)
          • Proper dose
        • Patient issues
          • Animal age
          • Freedom from disease
          • Concurrent use of medication
          • Pregnancy
          • Environment
      Copyright © 2011 Delmar, Cengage Learning
    • Vaccine Protocols
      • Practice of annual vaccination is now under debate
      • One way to discover when revaccination is necessary is via the antibody titer
        • An antibody titer is a serum test that reveals the level of antibody to a particular antigen in a particular individual
        • Antibody titers are expressed as 1:2, 1:4, etc., a ratio that represents the dilution at which the immune response is still adequate
      • Core vaccines are recommended for all individual animals
      • Noncore vaccines are recommended only for individual animals deemed to be at high risk for contact with the organism
      Copyright © 2011 Delmar, Cengage Learning
    • Species-Specific Vaccine Protocols
      • Examples of vaccines available for a variety of species are listed in the textbook
      Copyright © 2011 Delmar, Cengage Learning