Immunogens and Antigens in Microbiology
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Questions and Answers

Which term refers to a molecule of low molecular weight that cannot induce an immune response by itself?

  • Immunogen
  • Epitope
  • Antigen
  • Hapten (correct)
  • What is the definition of an immunogen?

  • A small site of simple chemical structure found on the antigen surface
  • An agent that induces an immune response when introduced to the host body (correct)
  • A large carrier molecule that can bind to haptens
  • An agent that binds specifically to components of the immune response
  • What is the relationship between immunogens and antigens?

  • All antigens are immunogens but not all immunogens are antigens (correct)
  • All immunogens are antigens and all antigens are immunogens
  • Immunogens are a subset of antigens and all antigens are immunogens
  • Immunogens are a subset of antigens but not all antigens are immunogens
  • What are antigen determinants or epitopes?

    <p>Small sites of simple chemical structures on the antigen surface to which antibodies or T-lymphocytes can bind</p> Signup and view all the answers

    Which type of molecules become immunogenic when coupled with carrier macromolecules?

    <p>Haptens</p> Signup and view all the answers

    What effect is associated with changes in antigen determinants?

    <p>Decrease in the specificity of antigen molecules</p> Signup and view all the answers

    What is the term for the number of epitopes on an antigen molecule that bind to antibodies?

    <p>Antigen valency</p> Signup and view all the answers

    Which phenomenon occurs when unrelated antigens share one or more identical epitopes, leading to the production of cross-reacting antibodies?

    <p>Cross reactivity</p> Signup and view all the answers

    Which factor influences immunogenicity by providing cross-protective immunity to related pathogen strains?

    <p>Foreignness</p> Signup and view all the answers

    Which chemical structure is considered non-immunogenic unless conjugated with protein to form lipoprotein or nucleoprotein?

    <p>Pure lipids</p> Signup and view all the answers

    At what molecular weight are substances considered potent immunogens?

    <p>Above 100,000 Dalton</p> Signup and view all the answers

    What is the term for a substance that, when mixed with antigen before its administration, induces the production of a stronger immune response against the antigenic substance?

    <p>Adjuvant</p> Signup and view all the answers

    Which route of administration generally induces a better immune response for immunogens?

    <p>Subcutaneous or intramuscular injection</p> Signup and view all the answers

    What factor influences immunogenicity by varying the ability to respond to a particular antigen according to the genetic makeup of animals?

    <p>Genetic constitution of the animal</p> Signup and view all the answers

    Which type of molecules become immunogenic when coupled with carrier macromolecules?

    <p>Polysaccharides</p> Signup and view all the answers

    What is the term for the ability of a substance to be immunogenic only when administered in an optimum dose?

    <p>Dose-dependent immunogenicity</p> Signup and view all the answers

    Study Notes

    Immunology Basics

    • A hapten is a molecule of low molecular weight that cannot induce an immune response by itself.
    • An immunogen is a substance that can induce an immune response, and an antigen is a substance that can bind to an antibody.
    • Immunogens are also antigens, but not all antigens are immunogens.
    • Antigen determinants or epitopes are the specific regions on an antigen molecule that bind to antibodies.

    Immunogenicity

    • Haptens become immunogenic when coupled with carrier macromolecules.
    • Changes in antigen determinants can lead to a loss of immunogenicity.
    • The valency of an antigen refers to the number of epitopes on an antigen molecule that bind to antibodies.
    • Cross-reactivity occurs when unrelated antigens share one or more identical epitopes, leading to the production of cross-reacting antibodies.

    Factors Influencing Immunogenicity

    • Genetic makeup influences immunogenicity by varying the ability to respond to a particular antigen according to the genetic makeup of animals.
    • Lipoproteins and nucleoproteins are considered non-immunogenic unless conjugated with protein.
    • Molecular weight is a factor in immunogenicity, with substances above a certain molecular weight (typically >5,000) considered potent immunogens.

    Immunogenicity Enhancement

    • Adjuvants are substances that, when mixed with antigen before its administration, induce the production of a stronger immune response against the antigenic substance.
    • The route of administration can influence immunogenicity, with some routes (e.g., intradermal) inducing a better immune response than others.
    • Dose is a factor in immunogenicity, with the optimum dose required for a substance to be immunogenic.

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    Description

    Test your knowledge about immunogens and antigens with this quiz based on the lecture contents from the Faculty of Veterinary Medicine, Alexandria University. Explore the concepts of antigens, immunogens, and their specific interactions with the immune response.

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