Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Virology Test 4 > immune defenses > Flashcards

immune defenses Flashcards

(78 cards)

Start Studying
1
Q

What is the purpose of the invariant chain?

A

It prevents peptides in the ER from binding on MHC II before they reach the endosome which contains extracellular proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What can kill multiple virus-infected cells?

A

CD*+ cytotoxic t cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What must also bind for Cyt. T cell activation?

A

Coreceptors ust bind as well. They facilitate adhesion of the two cells together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The MHC-peptide complex interacting with CD receptor is ____ in the chain of T-cell activation

A

signal 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how can virus affect T cell activation?

A

They can affect structure, function of T cell receptors. MHC can be downregulated in the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does a cyt. T cell work?

A

Release of perforins and granzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Perforin makes holes in _____ ____ . What do granzymes do? How long does it take?

A

endosomal membrane; cleave caspases to activate them; minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How long does it take for CTL activity appear?

A

3-5 days, peaking 1 week in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

If CTLS from an infected organism are transferred to a non-immunized recipient, can they protect them?

A

Yes they can

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Some immunopathology often follows infection by noncytopathic virus. Why?

A

CTLs kill infected cells. Ex: hepatitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Activating signal of B cells requires ___ of receptors complexed with antigen

A

clustering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

B cells have MHC II receptors in order to

A

Present antigens to Th2 helper cells in order to stimulate more cytokines for B cell stimulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

VL stands for:

A

Variable region of the light chain (antibody structure)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Fc stands for:

A

Fragment crystallizable (antibody structure)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How long of the half life of IgG?

A

7 to 21 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How long can specific IgG molecules be detectable in the body

A

years due to memory B cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

IgG and IgM are important for ____ infections

A

viremic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Immunodeficient animals can be protected from lethal viral infections by injection with ___ ____ ____ or monoclonal antibodies

A

virus-specific antiserum (passive immunization)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Poliovirus infection stimulates strong IgM and IgG response in blood, but ____ __ is vital for defense

A

mucosal IgA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What makes IgA?

A

Plasma cells in mucosal epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the primary mechanism of antibody-mediated viral neutralization?

A

steric blocking of virion-receptor interaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Antibodies can also promote aggregation of virions, what does this accomplish?

A

It reduces the effective concentration of infectious particles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

A negative effect of antibody can be that they ____ ____

A

enhance infectivity. Antibody bound to virions is recognizing by Fc receptors on macrophages, which allows it to enter the cell by endocytosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is another way that antibody can affect virus, especially during endocytosis?

A

Antibodies can prevent capsid uncoating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What starts from a single infected cell?
The cascade of antiviral defense
26
If viral replication isn't slowed after the cascade begins, what is then activated?
The immune defense
27
What are the three steps of the immune defense?
recognition, amplification, and control. It is also critical that it is stopped after the infection has abated.
28
When is the innate immune response activated? What are its components?
When the intrinsic defenses of the cells and tissue are unable to stop the infection; cytokines released from infected cells, local sentinel cells (dendritic cells and macrophages), the complement system, NK cells
29
What WBC cells are of lymphoid origin?
T cells, B cells, NK cells,
30
What WBC cells are of myeloid origin?
monocytes, dendritic cells, and neutrophils
31
Where is MHC II located on an immature dendritic cell? Toll-like receptors? cytokine receptors?
MHC II is located in endosomes. TLRs are on the exernal plasma membrane, as well as cytokine receptors
32
Where is MHC II located on a mature dendritic cell? Mature dendritic cells secrete ______ _____ in order to activate ___ cells
on the cell surface; proinflammatory cytokines; T
33
NK cells secrete ____, _____, and ____, _____ upon binding with a non-self MHC I molecule or MHC I without the proper protein
perforin, granzymes; TNF-alpha, IFN-gamma
34
How does the concentration of NK cells change with response to a viral infection?
The number of NK cells increases exponentially after infection, and then gradually decreases once the adaptive immune response kicks in.
35
How do granzymes kill a cell?
The activate caspase-mediated cell death.
36
The activating signal of a NK cell is delivered when an NK cell receptor binds and identifies a ____ _ _____ instead of binding the _____
MHC I molecule; peptide
37
What methods do virus use to modulate NK cell response?
1. Inhibition by a viral protein with homology (similarity) to cellular MHC class 1 2. Inhibition of expression of HLA-A or HLA-B, upregulation of HLA-E 3. Release of virus-encoded cytokine-binding proteins that block NK-cell activating cytokines. 4. Inhibition of action of NK cell stimulating cytokines by binding these or by producing a chemokine antagonist 5. New virions can engage the cell, block inhibitory NK cell receptor, or infect the NK cell.
38
What are HLA-A and HLA-B
MHC I human homologs
39
When are cytokines produced? What is the multifunctionary "early warning" cytokine? What are some of its functions?
Cytokines are produced when certain intrinsic defenses are activated; Tnf-alpha (produced by monocytes and macrophages); capillary changes that attract and facilitate entry of circulating WBCs, antiviral response in infected cells, inducing apoptosis of infected cells within seconds of TNF-a binding
40
What are the two major classes of lymphocytes? Where do T cells mature? What makes up the cell-mediated response?
T cells and B cells; the thymus; T cells and cytokines
41
What do immature T cells mature into?
Cytotoxic T cells and Helper T cells (both are effector T cells)
42
Where are B cells derived from? What response are they responsible for? What do they turn into?
Bone marrow; humoral response; plasma cells
43
How is the humoral response activated?
The humoral response is activated when an antigen binds the antibody on the B cell surface, prompting it to undergo differentiation into plasma cells
44
How is the cell-mediated response activated?
An antigen binds to a T cell receptor on a naive Cyt. T cell, causing it to kill the infected cell, or in the case of the helper t cell, to release Th cytokines 1 and 2, which promotes differentiation of T cells and B cells, respectively.
45
What are the two cell groups the adaptive response relies upon?
the adaptive response relies upon lymphocytes and antigen presenting cells.
46
Where do lymphocytes tend to settle?
Various lymphoid organs throughout the body
47
If lymph nodes are removed, how does this effect adaptive immunity?
Without lymph nodes, the immune response will not be activated.
48
What are lymphoid tissues the sites of?
They are the sites of communication, and collection, for cells in the circulatory system.
49
What happens to T and B cells that react against self proteins?
They die during early maturation
50
When T and B cells are made and mature, what do they do?
They lie in a dormant state in lymphoid tissues unless activated by the particular antigen or epitope that they protect against.
51
What do APC cells do?
They move back and forth from tissues to the lymphoid tissues.
52
What are lymph nodes the location of?
exchange of information between dendritic cells and lymphocytes
53
M cells are found where? What is their function?
in the submucosal epithelium of the GI tract. They function to allow transfer of antigen from intestinal lumen to lymphoid tissue. They have pockets filled with Th cells B cells macrophages and dendritic cells
54
What receptor would an infected cell display viral proteins on?
MHC I
55
What alternative immune activity do keratinocytes display?
They are able to phagocytose pathogens which they can display on MHC II receptors. they also secrete pro- inflammatory cytokines
56
How are T and B cell antigen receptors formed?
somatic gene rearrangement during organism development
57
What are the functions of lymphocytes?
They are responsible for specificity, memory, self/nonself discrimination
58
Why are T and B cells said to be naive?
They are naive when their specific receptor has not bound antigen, so they haven't completely differentiated to produce their ultimate immune effector response
59
The initial encounter with any foreign epitope involves only a few cells . The frequency of B or T lymphocytes that can recognize an infected cell is between:
1:10,000 to 1:100,000
60
How long does it take for the initial response to be fully amplified? what is the increase in virus-specific lymphocyte concentration?
1-2 weeks. 1000X
61
What is a lymphocyte that has been exposed to antigen called?
activated and fully differentiated.
62
When an activated lymphocyte undergoes mitosis, what specific quality to the progeny share?
They encode for the same specific immune reactivity as the parent cell.
63
Where are B cells produced? What does a B cell produce as it matures?
bone marrow; specific receptor which is a membrane bound antibody
64
When an antigen binds specifically to a membrane-bound antibody, what ensues? A _____ ______ cascade
signal transduction cascade; the cell divides rapidly
65
What are produced when a B cell begins to divide?
plasma cells and memory B cells
66
What is the life span of a plasma cell? What is the maximum rate of antibody secretion?
a few days; more than 2000 antibodies/second
67
The memory of previous infections is what made the development of _____ possible.
vaccines
68
When encountering a virus that the organism has previously been exposed to, a ferocious adaptive response can occur within ____ of exposure
hours
69
T-cell precursors are produced in the ____ ____
bone marrow
70
How can T-cells be distinguished from other lymphocytes?
The presence of a T-cell receptor on their surface
71
What are the types of T cell selection?
Positive selection involves selecting T cells that bind appropriate MHC surface molecules via TCR. Negative selection weeds out T cells that bind self peptides
72
What are the three types of cells a naive T cell can differentiate into?
Cytotoxic T cells, helper T cells, and memory T cells
73
How would you compare the peptide binding site of the TCR and the epitope binding site of the B cell receptor? How is this structure formed? What is another name for this region?
They are similar structures. They are formed by folding of the three regions in the amino-terminal domains of proteins that participate in antigen recognition; the hypervariable region
74
What is the process of T cell maturation?
Immature T cells are -- (double neg.) They differentiate sequentially in thymus, producing both CD4 and CD8 ++. Afterwards, they begin to just produce one type +, and are now "naive T cells", and migrate to peripheral sites.
75
Th cells are generally able to interact with cells with which receptors on their surface? After this interaction, what do they mature into?
MHC Class II; Th1 and Th2 cells
76
What proinflammatory cytokine secreted by Th cells is important for viral infections? Which T helper cell would secret this, and which adaptive response would this encourage?
IL-12; Th1; cell mediated response
77
What does cytokine IL-4 do?
IL-4 induces naive Th0 cells to become Th2 cells
78
Viral proteins can take advantage of Th1-Th2 balance. For example, when Epstein-Barr Virus infects B cells, it encodes a ____ homolog that suppresses the Th1 response. What are the advantages of this for the virus?
IL-10 (vIL-10); This causes the cell to foil the Th1 defense that would help with cell-mediated defense, and also causes B cells to differentiate, which is vital to the virus' survival

Virology Test 4 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions