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Ch 18 Immune Responses to Infectious Diseases
Immune Responses to Infectious Diseases
54
Biology
Undergraduate 4
05/09/2011

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Cards

Term
What are the three steps needed to establish infection?
Definition

1) Penetrate the Epithelial barriers: not easy

  - skin, GI lining, and Respiratory lining

2) Compete w/  Normal flora for Binding Sites

  - Lactobacillus Acidophilous

  - Bifidobacterium Bifidus

3) Evade Innate Immunity

  - Macrophages, Neutrophils and Natural killer cells. 

Term

Innate Immunity

a) What receptors are expressed on Inn. Imm. cells to identify bacterial molecules?

b) What do viruses induce production of?

Definition

a) TLR-4: recognize LPS, gram negative bacteria

   TLR- 2: recognize PGN, gram positive bacteria

    TLR-3,7,9: Viral nucleic acids

b) induce production of interferon Alpha, beta and  

    gamma which produce an anti-viral state.

Term

How do pathogens trick to avoid the immune system?

Definition
  • start living inside cells
  • mimic the surface of host cell
  • acquire a covering of host membrane molecules
  • induce specific type of immunity that allows it to survive
  • continuous variation of antigens. ex HIV
  • express antigens that resemble our own genes.
Term

Viral Infections

a) How does the innate immune system respond via detection and destruction of viruses?

b) What two components do the adaptive immune system use to respond to viral infections?

Definition

a) detection: by Toll-like Receptor (TLRs)

    destruction: by interferons and NK cells

b) cell-mediated and humoral components

Term

Viral Infections

a) Why do viruses need a host?

b) Are infections intracellular or extracellular?

c) How do they survive from host to host?

Definition

a) in order to replicate

b) Intracellular

c) long latency periods that can be seen in AIDs

  - infection efficiency (Influenza)

  - use of non-host species vectors (west nile virus)

 

Term

Viral Infections

a) What genetic information of viruses induces production of IFN?

b) What types of IFN is produced by pDCs?

c) Which TLR respond to dsRNA and ssRNA?

d) What does the anti-viral state inhibit?

Definition

a) dsRNA

b) IFNalpha and IFN beta

c) TLR 3 responds to dsRNA and TLR7 responds to ssRNA

d) inhibit replication and infection

Term

Humoral

What activity does the effector molecule antibody (sIgA) under go?

Definition
blocks binding of virus to host cells, thus preventing infection or reinfection.
Term

Humoral

What activity does the effector molecule IgG, IgM and IgA antibody do?

Definition
blocks fusion of viral envelope with host cell's plasma membrane.
Term

Humoral

What activity does effector molecule IgG and IgM antibody do?

Definition
Enhances phagocytosis of viral particles (opsonization)
Term

Humoral

What does IgM antibody do to respond to viruses?

Definition
Agglutinates viral particles
Term

Humoral

What activity does complement activated by IgG or IgM antibody do?

Definition
Mediates opsonization by c3b and lysis of enveloped viral particles by membrane attack complex.
Term

Cell-mediated Response

What activity does IFN gamma secreted by Th or Tc cells undergo?

Definition
direct antiviral activity
Term

Cell-mediated Response

What activity do cytotoxic t lympohocytes have?

Definition
kill virus-infected self cells
Term

Cell-mediated Response

What activity do natural killers and macrophages have?

Definition
kill-virus infected cells by ab-dependent cell-mediated cytotoxicity (ADCC)
Term

Explain is viral replication prevented?

[image]

Definition

 

IFN alpha/beta binds to the IFN alpha/beta receptor cause dimerization  cell signal transduction on cytoplasmic tail will produce two pathways

      1) 2,-5 (A) synthase will activate 2-5(A) with ATP   

      then activate RNAse L and degrades poly(A)mRNA

       and get inhibition of protein synthesis

    2)  protein kinase becomes activsted with ATP

        and dsRNA which phosphorylates elF-2 which       

         makes it nonfunctional and get inhibition of

         protein synthesis

 

Term
What cells become activated when IFN signaling occurs?
Definition
NK cells begin eliminating virally infected cells.
Term

a) How do antibodies protect against viruses?

b) Viral entry is mediated through receptors, what receptors do influenza virus and rhinovirus bind to?

 

Definition

a) ab bind to viral surface antigens to 1) protect against re-infection 2) huge amounts of sIgA in lumen block viral attachment

 

b) influenza virus binds to sialic acid on glycoproteins
    rhinovirus binds to ICAMs

Term
What does oral polio vaccine rely on
Definition
IgA production
Term

a) When infection occurs, does cell-mediated or humoral immunity (or both) eliminate infected cells?

 

 b) What cells are the participants? What cytokines are produced and what is the time frame of their peak.

Definition

a) Only Cell-mediated immunity

 

b) Th1: IFN-gamma (induce antiviral state) IL-2 (Expands CTL-P) and TNF-alpha. IL2 and IFN gamma activate nk cells

 

CTL : peaks 7-10 days post infection

   - elimate virally infected cells

Term
how does hepatitis c virus evade the immune system?
Definition
anti viral effect of IFNs by inhibitinh action of PKR
Term
how does herpes simplex virus evade the immune system?
Definition
decreases the expression of MHC class I to avoid CTL elimination
Term
How does cytomegalovirus evade the immune system?
Definition
by decreasing the expression of MHC I
Term
How does HIV evade the immune system?
Definition
Decreases MHC II expression, No TH1 support for CTL
Term
How oes the influenza virus evade the immune system?
Definition
Antigens are constantly changing via antigenic shift and antigenic drift
Term
What are the two receptors on the influenza virus?
Definition
Hemagglutinin and Neuraminidase
Term
What are the characteristics of an influenza virus?
Definition
  • virion is 90-100 nm
  • surrounded by plasma membrane of host
  • 2 glycoproteins on surface; hemagglutinin (HA; viral attachment to sialic acid on glycoproteins) and Neurominidase (NA; detach from sialic acid aka budding)
  • matrix protein beneath lipid bi-layer
  • nucleocaspid contains 8 ssRNA which associated w/ RNA polymerase and protein. Each ssRNA encode for one or more proteins.
Term

a) What is the type of influenza dependent on?

b) What are the types?

c) Which type is responsible for major pandemics in humans?

d) how many variants are in HA and NA?

Definition

a) matrix composition and nucleoprotein composition

b) A,B,C

c) A

d) Ha- 13 and NA- 9

Term
What is the difference between antigenic shift and antigenic drift?
Definition
Antigenic drift has a slight change to the RNA of the virus, while antigenic shift has a major change within swine causing a pandemic.
Term
Why is it that immune protection is lost during antigenic drift?
Definition
The humoral response is strain specific, therefore it will not be able to produce antibodies against it. The antibodies are generated against tip and loop; the domains surrounding the binding cleft.
Term

a) Are antibodies necessary for recovery?

b) is reinfection possible?

Definition

a) No, recovery occured in mice that had antibodies suppressed.

b)Re-infection is possible.

Term
What are the three cells responsible for viral elimination
Definition
pDC, NK, and CTL
Term
What signals do hepatitis C block?
Definition
IFN alpha and IFN beta
Term
What does Herpes simplex virus inhibit?
Definition
inhibition of antigen presentation via TAP, Blocks action of complement.
Term
How are bacterial infections eliminated?
Definition
Humoral immunity with extracellular bacteria, but not for intracellular bacteria.
Term
What is important in the elimination of intracellular bacteria?
Definition
DTH
Term
How are the many ways that antibodies eliminate bacteria or bacterial toxins?
Definition
  • opsonization of bacteria
  • neutralization of toxins (exotoxins eg. diptheria and endotoxins e.g LPS)
  • lysis of bacteria through complement pathway
  • complement activation through mast cell activation results in localized inflammation
       - vasodiation and extravasation (neutrophil 
         accumulation)
Term
How does bacteria enter the host?
Definition
via Respiratory tract, GI tract, Genuitourinary tract, skin
Term
How does ab-mediated mechanism combat extracellular bacteria?
Definition
  1. bacteria will evade
  2. ab will neutralize bacterial toxins
  3. complement-mediated lysis of bacteria
  4. ab and complement split profuct c3b bind to the bacteria serving as opsonins to increase phagocytosis
  5. c3a and c5a induce local mast degranulation, releasing substances that mediate vasodilation and extravasation of lymphocytes and neutrophils.
  6. other complement products are chemotactic for neutrophils and macrophages.
Term
Bacterial infection have four steps, what are they?
Definition
  1. attachment
  2. proliferation
  3. invasion of host tissue
  4. toxin induced damage to host cells
Term
What do bacterias use for attachment?
Definition
  • pili
  • adhesion molecules (Bordetella Pertussis)
Term
What is IgA's responsibility during an immune system response?
Definition
  • prevent attachment of bacteria
  • some bacteria can overcome via protease decreasing 1/2 life of IgA eg. Heamophilus Influenzae
Term
How do some bacteria avoid phagocytosis?
Definition
Having a polysaccharide capsule around the bacteria
Term
How can an immune response against a pathogen cause pathogenesis?
Definition

Overzealous immune system can be pathogenic

  - bacterial septic shock
        - predominant cytokines involved: IL 1 and TNF-a

        - Source: Macrophages

  - intracellular bacteria cause granulomas
        - extensive tissue damage 
        - eg. tuberculosis

Term

a) What bacteria causes tuberculosis?

b) What happens after macrophage Ingest?

c) What cells are granulomatous lesion formed from? What do the lesions do?
d) What cytokines eliminate the pathogen?

Definition

a) Mycobacterium Tuberculosis

b) Cannot digest pathogen, the pathogen will eventually replicate itself and burst releasing bacilli

c) Macrophage and TH1 cells produce the lesions which are containment and destruction of healthy tissue

d) IL-12 and IFN gamma

Term

Immune Response contributing to disease

a) What is septic shock induced by?

b) What cytokines are responsible?

Definition

a) endotoxins

b) IL-1 and TNF alpha

Term

Immune Response contributing to disease

a) What is shock induced by?

b) what is an example of a pathogen?

Definition

a) superantigen exotoxins

b) Staphylococcus

Term

Immune Response contributing to disease

Granulomas are chronic activation of what cells?

Definition
CD4+
Term

Immune Response contributing to disease

What disease do antibodies to flagella contribute to WHAT TYPE of hypersensitivity?

Definition
Lyme disease, type III
Term

Evasion of immune system

How does Gonorrhea evade the immune system?

Definition
  • enhanced attachment to host cells
  • proteases that cleave IgA
  • changing surface antigens
Term

Parasitic Diseases

a) What are some examples of the diseases that are caused by protozoans??

b) What immunity is active during the location of the blood born-stages?

c) What immunity is necessary during the location of infection of host cells?

Definition

a) Malaria and African sleeping sickness (Trypanosoma)

b) humoral antibody

c) cell-mediated immunity

Term

a) What type of species does the disease malaria come from?

b) How many people are affected world wide?

c) What is the life cycle?

d) How does it evade the immune system?

Definition

a) Plasmodium

b) 600 million

c) Blood --> liver --> RBCs

d) Change antigens during maturation, intracellular proliferation, sporozite in blood only 30 minutes and can slough off antigen coat.

Term
Why are parasitic diseases of helmiths difficult?
Definition
Parasites are large and exposure to the immune system is limited.
Term

Fungal diseases (Mycosis)

a) What are some examples of cutaneous infections?

b) Where are subcutaneous infections? How?

c) how is in controlled?

Definition

a) athletes foot, jock itch, and ringworm

b) secondary infections of lungs, CNS, bones and abdomen by ingestion, inhalation or innoculation into the blood stream.

c) phagocytosis via neutrophils, controlled by innate barriers, activation of complement

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