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Flashcards in Immune Response to Pathogens Deck (12)
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1

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

2

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

3

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

4

describe the influenza virus cycle

5

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

6

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

7

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

8

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

9

describe bacterial strategies to avoid immunity

10

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

11

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

12

which cytokine is involved in fungal immunity?

IL-17

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