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Flashcards in Immune Response to Pathogens Deck (12)
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name the humoral immunity responses to viruses

  • antibody: neutralization; antibody-dependent cell-mediated cytotoxicity (ADCC) and complement activation
  • interferon (alpha and beta): produced by virally infected cells
    • inhibit transcription and translation in neighbor cells
  • IFN-gamma: activates macrophages and NK cells and enhance adaptive immune system upregulating expression of MHC class I and II


name viral strategies to avoid immunity

  • antigenic shift and drift (e.g. influenza): mechanism of antigenic variation
  • polymorphism (e.g. adenovirus, rhinovirus): circumvents immunologic memory by expressing different immunologic targets
  • latent virus (e.g. herpes simplex virus, varicella-zoster)
  • modulation of MHC expression (e.g. adenovirus, EBV, CMV, HSV, VZV)
  • infection of lymphocytes and their death (e.g. HIV, measles, CMV)
  • prevention of complement activation


describe orthomyxoviruses (influenza)

  • 3 distinct influenza virus type: A, B, C; type A causes infxns
  • viral infection:
    • virus attaches to and multiplies in the cells of the respiratory tract
    • segments of RNA genome enter the nucleus (transcribed/translated)
    • finished viruses are assembled and budded off the cell with an envelope


describe the influenza virus cycle


describe the glycoprotein spikes on influenza viruses

  • hemagluttinin (H): 15 different subtypes; most important virulence factor; binds to host cells
  • neuraminidase (N): 9 subtypes - hydrolyzes mucus and assists viral budding and release


contrast antigenic drift and antigenic shift

  • constant mutation is called antigenic drift--gradually change their amino acid composition
  • antigenic shift--one of the genes or RNA strands is substituted with a gene or strand from another influenza virus from a different animal host
    • genome of virus consists of 10 genes encoded on 8 separate RNA strands


describe cell-mediated immunity with bacteria

  • phagocytic cells kill most bacteria
  • helper T cell is required for the generation of the antibody response (Th2 help)
  • B-cells can recognize protein and non-protein antigens


describe the humoral immunity response to extra-cellular bacteria

  • complement: activated via the lectin or alternative pathway
    • C3b: opsonin
    • C3a and C5a: recruit leukocytes
    • MAC: perforate outer lipid bilayer of G-ve bacteria
  • lysozyme: antibacterial that attacks NAM-NAG links (peptidoglycan) in the bacterial cell wall which result in lysis
  • antibody: principal defense against extracellular bacteria
    • neutralization
    • activation of complement
    • opsonization


describe bacterial strategies to avoid immunity


describe the immune response to protozoal infections

  • protozoa are microscopic; single-celled organisms
  • protozoa cause intracellular infection, have marked antigenic variation and are often immunosuppressive
  • they have complex life cycles, with several different stages and therefore present the immune system with a variety of challenges
  • protozoal infection is often chronic since the immune system is not very efficient at dealing with these organisms
  • most of the pathology of protozoal disease is caused by the immune response


describe the immune response to fungi

  • innate immunity controls most fungal infections
    • phagocytosis by neutrophils is a strong defense against most fungi
    • the alternative and lectin pathways of complement activation are triggered by components present in most fungal cell walls


which cytokine is involved in fungal immunity?


defective Th17 cell differentiation has been linked to recurrent filamentous fungi and the occurrence of mucocutaneous candidiasis in patients with primary immunodeficiencies