Subversion of immunity/immunodeficiency Flashcards

1
Q

Immunity to microbes and subversion of the immune response

A

how pathogens make their way in the face of the human defenses

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2
Q

Effective immunity to extracellular bacteria

A

Antibody
- neutralization
- opsonixation and Fc receptor-mediated phagocytosis

Complement activation
- Phagocytosis of C3b coated bacteroa (opsonization)
- Inflammation
- Lysis of microbe

^ work together with phagocytes to lead to the destruction of extracellular bactera.

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3
Q

Th17 type

A

T helper response is favorable for clearance of extracellular bacteria

It recruits neutrophils.

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4
Q

immunity to intracellular bacteria

A

Innate and adaptive immunity

Live inside host cells

Must be either killed by T cells or killed by the host cell which has to be activated.

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5
Q

intracellular bacteria molecules

A

IL12
IFNy

work in both innate and adaptive immunity

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6
Q

IL 12 secreted by macrophages

A

can activate NK cells, and T helper to make IFNy.

IFNy can perform macrophage activation

and cells (Th1)

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7
Q

intracellular bacteria response

A
  1. IL12 response from macrophage or APC
  2. IL12 acts on T cell which makes IFNy
  3. Leads to macrophage activation
    - phagocytosis and bacterial killing
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8
Q

IFNy produced by

A

CD4 T helper cells, not only supports macorphage activation but also supports CD8 T cell actvivation and killing of infected cell.

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9
Q

virus immunity (live inside cells)

A

Innate response
- type I interferon (IFNalpha and Beta) - creates an anti viral state
- NK cells

Adaptive response
- Antibody - neutralization
- CD8 + CTL - killing and eradication of established infection

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10
Q

Extracellular bacteria key players

A
  • Th17
  • neutrophils
  • antibodies
  • complement
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11
Q

Intracellular bacteria key players

A
  • Th1
  • IFN-gamma
  • macrophage activation
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12
Q

viruses - key playeres

A
  • Type I IFN
  • NK cells
  • Neutralizing antibody
  • CTL
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13
Q

Kinetics of immune response to virus

A

Virus titer - highest at day 5. cleared by day 12

Innate response
1. Type I interferon
2. NK cells

Adaptive response
1. Virus specific CTL
2. Antibody

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14
Q

What are strategies pathogens use to survive in human host?

A
  • Change what they are “wearing” (changes in their antigens)
  • hide out and rest
  • disrupt antigen processing and presentation
  • inhibit or suppress innate or adaptive immunity
  • Live as a community in a biofilm
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15
Q

S. pneumoniae, comes in different

A

serotypes
- type of antibody response, based on capsule polysaccharides
- “changing what they are wearing”

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16
Q

serotype

A
  • many bacteria evade host immunity by existing as different strains which differ in the antigenic molecules on their surface
  • serological assays are used to determine the identity of bacterial strains based on the antibodies that bind them
  • Following an infection with one bacterial serotype, a patient will have protective immunity to that strain, but not a different serotype
17
Q

Vaccines against streptococcus pneumoniae

A
  • Polysaccharide vaccine
  • Conjugate vaccine
18
Q

Polysaccharide vaccine

A

consists of purified polysaccharides from 23 different serotypes
- Pneumovax
- T-independent, IgM produced (type 2 response)
- Immunity is not as robust or long lasting, but serotype coverage is broad

19
Q

Conjugate vaccine

A

capsular polysaccharide coupled to diptheria toxoid
- Prevnar 7 and Prevnar 13 are two brands
- T dependent immunity, other isotypes, B cell memory
- Immunity is more robust, but serotype coverage is more limited

20
Q

antigenic drift

A

way for influenze to change its “antigenic clothes”

  • small change in one person, let another person unable to have a secondary immune response

small changes to viral genome that result in changes in the anitgens and their desired binding to surfaces

21
Q

antigenetic drift definition

A

viruses such as influenza are prone to mutations. Point mutations in certain antigens (H and N) are sufficient to alter antibody binding, creating a means of escape from the existing antibody response

22
Q

antigenic shift

A

more dramatic changes in the virus in which new recombinant viral genomes are generated in cells infected with two distinct viruses (human and avian) leads to more spread, pandemic.

23
Q

anitgenic shift - more dramatic

A

results in a different virus that no one has pre-existing immunity to

  1. a secondary host is infectied with a human and an avian strain of virus
  2. recombination of viral RNA in the secondary host produces virus with a different hemagglutinin
  3. No cross protective immunity in humans to virus expressig novel hemaggluthinin
24
Q

human influenza virus

A

8 RNA segment genome
Neuraminidase
Hemaglutinin

25
avian influenze virus
- HA gene - NA gene
26
Latency
a dormant, a state in which replication does not occur. Ex: herpes simplex virus. - little viral gene expression is observed - virus can hide in this state for long periods - Upon reactivation, the immune response can respond to viral infection stress induce reactivation of the virus.
27
Virus that is immunosuppressive
**Epstein Barr Virus** Produces cytokine homoloh of IL10 Inhibits Th1 lymphocytes Reduces IFNy production
28
Viral mechanism to inhibit antigen processing and presentation
Removal of Class I from ER: CMV Reduces expression of MHC class I expression on the cell surface
29
Biofilms
- surface attached community of bacteria encased in polymeric matrix - protected from a number of stresses or immune defenses - less sensitive ROI, phagocytosis, complement, neutrophil attack Characteristics of many mucosal infections: Otitis, pneumonia
30
*change what they are wearing*
streptococcus pneumonia **influenza** - antigenic shift - antigenic drift
31
*hide out and rest*
Herpes Simplex Virus (HSV)
32
*Disrupt antigen processing and presentation*
several viruses, CytoMegalo Virus (CMV) is best example
33
*Inhibit or suppress innate or adaptive immunity*
EBV-IL10-Homolog
34
*live as a community in biofilm*
Haemophilus influenzae
35
*Extracellular bacteria*
- complement - neutrophils - antibody - Th17
36
*intracellular bacteria-*
- macrophages - IL12, which leads to IFN gamma production from CD4+ Th1 cells - macrophage activation - CTL contributes too