Chapter 21 Vaccines Copyright 2011 Delmar Cengage Learning

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Chapter 21 Vaccines Copyright © 2011 Delmar, Cengage Learning

Chapter 21 Vaccines Copyright © 2011 Delmar, Cengage Learning

Immunity • Nonspecific immunity – Includes things such as physical barriers, mucus production, inflammation,

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 –

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

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

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

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

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

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

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

Vaccines • Types of vaccines (cont. ): – Polyneucleotides: or DNA vaccines injects DNA that encodes 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

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

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 –

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 singleantigen 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

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 • 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 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

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

Species-Specific Vaccine Protocols • Examples of vaccines available for a variety of species are listed in the textbook Copyright © 2011 Delmar, Cengage Learning