Chapter 17

Front 1

What are the INNATE immune responses to infectious diseases?

Back 1

-Inflammation
-Complement system
-NK ADCC
-Cytokines

Front 2

What are the SPECIFIC responses to infectious diseases?

Back 2

Cell-mediated response (CTL)
Humoral response

Front 3

Why do viruses present a unique challenge to the immune sytem?

Back 3

They are intracellular pathogens and must be combated with cell-mediated immunity; humoral response is insufficient.

To inhibit the pathogen, the host cell must be affected as well.

Front 4

What is a retrovirus?

An example:

Back 4

A virus which inserts its dna into the host's genome.

HIV

Front 5

What are the 3 main purpose of the Humoral response to infecton:

Back 5

1. Defend AGAINST infection
2. Prevent SPREAD of infection
3. Neutralize viral infection by ADCC

Front 6

How des IgA defend against infection?

Back 6

It is secreted to the mucosal membranes and prevents pathogens from binding to host cells.

PREVENTS infection or reinfection

Front 7

An action done by IgA, IgG and IgM:

Back 7

prevention of viral fusion with the host cell membrane - the pathogen got through the mucosal membrane, but is prevented from inserting DNA into genome.

Front 8

How do IgG and IgM function in the humoral response to infection?

Back 8

Both act as opsonins by binding FcR on phagocytic cells. Allosws CLEARING of infection

Front 9

What is a function of IgM alone in the humoral response:

Back 9

Agglutinates viral particles - a macroprocedure, but effective nonetheless.

Front 10

How is complement activated by the humoral response to infection?

Back 10

When IgM and IgG opsonize, their Fc regions have C3b receptor; C3b can bind the complex and induce MAC construction and lysis.

Front 11

What are the 3 components of the cell-mediated response to infection

Back 11

IFN-y secretion
Cytotoxic T lymphocytes (CTLs)
NK cells

Front 12

What do the three components do?

Back 12

IFN-y is secreted by T cells; has antiviral activity.

CTLs kill virus-infected cells.

NK cells and macrophages kill virus-inf. cells via ADCC while Cell-med. response is being mustered.

Front 13

If you're told to describe the INNATE RESPONSE TO VIRAL INFECTION:

Back 13

IFN-y induces direct antiviral activity;

IFN-a and B stop viral dna replication and protein production.

NK cells are the first-line defense; kill virus-infected cells by ADCC.

Front 14

Which set of cytokines is important in a viral infection?

Back 14

Type I interferons

Front 15

What are the functions of IFN a/b

Back 15

-inhibit viral dna replication and protein synthesis

-activate NK cell activity

Front 16

What are the 4 basic ways viruses can evade their host's defense system?

Back 16

1. Block Antigen presentation
2. Block the complement pathway
3. Block recognition
4. Block host defense

Front 17

How does a virus block antigen presentation?

Back 17

By inhibiting the TAP molecule so that degraded virus cannot be presented on the surface of the infected cell as antigen.

Front 18

How does a virus block the complement pathway of its host to evade the host's defense

Back 18

1. Bind c4b to prevent opsonization of viruses; prevents MAC lysis.

2. Alter the protealysis pathway

Front 19

How does a virus block recognition of itself to evade the host defense system?

What is the purpose?

Back 19

This is a DISGUISE, by two mechanisms:

-Antigen drift
-Antigen shift

Front 20

What are the characteristics of
ANTIGEN SHIFT

Back 20

-A drastic change in the virus subtype;
-Results from genetic recombination between different species to produce a new subtype of the virus.

-Causes a pandemic

Front 21

What are the two molecules on the surface of the flu virus?

Back 21

-Neuraminidase (facilitates budding)

-Hemagglutinin (attaches host to cells)

Front 22

How is the genetic material stored in the flu virus?

Back 22

in 8 strands of RNA.

possible to reassort.

Front 23

What causes antigen drift, what is the result?

Back 23

Caused by point mutations that occur all the time; results in surface molecules slihtly different, but can still cross-react so there is some protection.

LOCAL epidemic

Front 24

What are 6 ways viruses can directly BLOCK the host immune system defense?

Back 24

1. Infect lymphocytes/macrophages
2. Inhibit cytokine functions (mimic or block receptors)
3. Cause cytokine imbalances (suppress cytokine production)
4. Kill T and B cells
5. Be a retrovirus
6. Downregulate MHC expression

Front 25

What does polychromatic mean?

Back 25

There are 8 seperate strands of RNA within the flu virus; these can recombine with other virus rna

Front 26

Why does Antigen drift occur?

Back 26

RNA polymerase is not high-fidelity, so many mistakes occur in the replication process.

Front 27

How does the immune system respond to bacteria?

Back 27

If Extracellular: produces humoral antibody.

If Intracellular: Delayed Type Hypersensitivity DTH

Front 28

Why does a DTH develop in response to intracellular bacteria?

Back 28

Because this response is cell-mediated, and these bacteria are only presented on MHC and induce a cell-mediated response.

Front 29

what is a protease inhibitor?

Back 29

A drug useful for combating viral infection that inhibits reverse transcriptase and viral gene replication

Front 30

what is the target of the AIDS virus?

Back 30

the Thelper cell

Front 31

How does the AIDS virus recognize Thelper cells?

Back 31

It recognizes CD4 and serpentine chemokine receptors; after entering the cell it becomes a

PROVIRUS

and lives for a while.

Front 32

Cell receptors necessary for AIDS to enter cell; which cells?

Back 32

Monocytes; must have CD4 and Chemokine receptors.

Front 33

5 ways Antibodies combat extracellular bacterial infections:

Back 33

1. Bind/neutralize toxin produced..
2. Lysis of bacteria by activating complement (alternative pathway).
3. Ab/C3b bind bacterial surface; opsonins for phagocytosis.
4. C3a anaphylatoxin causes inflammation.
5. Chemotaxis for WBC response

Front 34

Immune responses to bacteria can be pathogenic, rather than the bug itself; what are some examples?

Back 34

Endotoxin causes septic shock

Exotoxin functions as superantigen, resulting in huge cytokine production.

M. tuberculosis - pathogens living intracellularly cause DTH, chronic antigenic activation of Thelper cells.

Front 35

2 types of intracellular pathogens and the immune response:

Solution:

Back 35

Leprosy, Tuberculosis

DTH


DRUGS, taken for a loooong time.

Front 36

What happens in an infection of tuberculosis?

Back 36

Bacteria lives intracellularly in macrophages.
Chronic Ag presentation to CD4 tcells.

EFFECT of activated Tcells -> CTLs release lytic granules to kill targets.

Chemotaxis for activated macrophages causes granuloma -> TUBERCLE walls off bug.

Front 37

4 ways that bacteria invade the host:

Back 37

1. Attach to host cells
2. Proliferate
3. Invade host tissues
4. cause damage with toxins

Front 38

4 ways hosts defend against bacteria:

Back 38

1. block attachment to host cells with IgA
2. prevent prolif by opsonizing for phagocytosis; or by MAC-lysis and inflammation.
3. Use Ab-mediated agglutination to prevent invasion of tissues
4. Neutralize toxins with antibody

Front 39

6 mechanisms by which bacteria evade the host defense against the bacteria:

Back 39

Secrete proteases to cleave IgA
Vary Antigenic structure
3. Inhibit phagocytic cells
4. Resist MAC insertion (Gram pos)
5. Membrane molecules to resist MAC insertion (GRAM neg)
6. Secrete molecules to inactivae C3a/b
etc.

Front 40

Life cycle of Protozoa

Back 40

Plasmodium
1. Blood meal; sporozites enter blood.
2. To liver; multiply, transform liver cells, release many babies.
3. babies infect RBC, rupture, release more babies.
4. Get ingested by another mosquito eating; differentiate, transmitted agian.

Front 41

What causes malaria?

Back 41

plasmodium, a protozoan

Front 42

4 Challenges of Plasmodium:

Back 42

1. Many phases in life cycle make specific immune response difficult.
2. Many babies - MUCH Ag;
3. Sporozoites only circulate 30 min before going to liver.
4. Sporozoites antigenic phenotype changes alot

Front 43

Solutions for Malaria:

Back 43

develop a vaccine
develop new drugs to replace old resistant ones

Front 44

best stage of plasmodium life cycle to administer a vaccine:

Back 44

the sporozoite stage (before going to the liver and having babies)

not useful tho, becuase this is only 30 minutes and immune response takes longer

Front 45

what is Schistosomiasis?


How is it transmitted

Back 45

disease caused by Schistosome - a parasitic worm.

Contact with swimming larvae

Front 46

Process of Schistosomiasis:

Back 46

1. Larvae bore between toes
2. enter capillaries/blood Travel to Mesenteric veins or the bladder.
3. Mature into adult worms.
4. Have eggs; get into feces and urine.
5. Spread eggs.

Front 47

Where would be the best vaccine to schistosomiasis?

Back 47

Early in the stage of infection, maybe the larvae or adult worms but before generation of eggs.

Front 48

What are the challenges presented by schistosomiasis?

Back 48

1. only one worm, hard to stimulate immune response.
2. only one worm; hard to find it to neutralize.
3. Motile worm; evades immune response that is generated.
4. worm expresses ABO antigens; not recognized as foreign