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virology > Exam1 Host response > Flashcards

Exam1 Host response Flashcards

1
Q

Which of the following are may be activated in host response to Viral infections?

a. innate immunity
b. adaptive immunity
c. passive immunity
d. all of the above

A

d. all of the above

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2
Q

Which of the following are characteristics of innate immunity?

a. no antigen specificity or memory
b. antigen specificity but no memory
c. antigen specificity and memory

A

a. no antigen specificity or memory

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3
Q

Innate immunity is part of :

a. first defense
b. second defense

A

a. first defense

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4
Q

Which of the following is true of innate immunity?
They are the only immune defenses available for the :
a. last few days after viral infection
b. first few days after viral infection

A

b. first few days after viral infection

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5
Q

Physical and chemical defenses are part of which line of dense?

A

first.

viruses must first breach these barriers at portal of entry before they can cause infection.

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6
Q

Which of the following are NOT defenses used by the skin?

a. presence of fatty acids
b. high pH
c. dryness
d. dense outer layer of keratin

A

b. high pH

LOW pH

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7
Q

Mucous membranes of the conjunctiva, oropharynx, and genitourinary tract use this protein :

a. albumin
b. virucidal
c. milk
d. glycoprotein

A

b. virucidal

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8
Q

Which of the following is not a characteristic of first line defense in the GI tract?

a. acidity of the intestine
b. lipolytic activity of bile
c. mucus layer covering gut
d. Defensins

A

a. acidity of the intestine

the intestine is ALKALINE

the stomach is acidic

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9
Q

Which of the following are NOT mechanisms of first line of defense in the respiratory tract?

a. mucociliary blankey
b. acidic environment
c. temperature gradient

A

b. acidic environment

larger particles >10um are trapped in the mucociliary blanket and swallowed or coughed up.

Temperature gradient between nasal passage (33celcius) and alveoli (37celcius)

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10
Q

T/F NK cells are granulated.

A

TRUE

NK cells are large lymphocytes, defined by cytoplasmic granules

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11
Q

T/F NK cells provide specific resistance against viral infections

A

FALSE

NK cells provide NONspecific resistance against viral infections

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12
Q

Which of the following are not contained in cytoplasmic granules of NK cells?

a. perforin
b. granzymes
c. defensin

A

c. defensin

perforin - produce pores in plasma membrane

granzymes - proteins that can initiate apoptosis

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13
Q

T/F NK cells synthesize the release of cytokines and interleukins that stimulate their own proliferation and cytolytic activity.

A

True

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14
Q

T/F healthy cells express class II MHC molecules, and are not attacked by NK cells.

A

FALSE healthy cells express class I MHC molecules, and are not attacked by NK cells.

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15
Q

In virus infected cells, ____ expression is reduced so that NK cells are activated and kill the infected cell.

a. MHC class I
b. MHC class II
c. MHC class II

A

a. MHC class I

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16
Q

Which of the following do NOT have PAMPS :

a. viruses
b. host cells
c. microbes

A

b. host cells

PAMPS are macromolecules recognized by cells at portals of virus entry.

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17
Q

Which of the following express pattern recognition receptors (PRR)?

a. macrophages
b. dendritic cells, NK cells
c. neutrophils,
d. all of the above

A

d. all of the above

PRR are receptors on these cells that recognize PAMPS on viruses and microbes

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18
Q

cells of innate immune system respond in which of the following ways when their PRR is bound to PAMPs?

a. expression of IFN and inflammatory cytokines
b. activation of phagocytic cells
c. macrophages initiate chemotaxis
d. all of the above

A

d. all of the above

If persistent activation of these receptors by viruses, can have continuous production of inflammatory mediators resulting in damage to host.

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19
Q

What are interferons?

A

IFN are a group of cytokines (complex glycoproteins) that are secreted by somatic cells in response to viral infections and other stimuli

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20
Q

T/F interferons show virus specificity.

A

FALSE

interferons show NO virus specificity.

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21
Q

Which of the following are stronger inducers of interferons?

a. DNA viruses
b. RNA viruses

A

b. RNA viruses

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22
Q

T/F interferons should be administerd to the patient orally

A

FALSE
interferons should be administerd to the patient BY INJECTION.

interferons are orally inactive!

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23
Q

Type-1 IFN allfa is :

a. not host specific
b. host specific

A

a. not host specific

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24
Q

Type-1 IFN beta is :

a. not host specific
b. host specific

A

b. host specific

generally

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25
Q

T/F the two major type-I interferons are produced by virus infected cells within minutes of viral invasion.

A

FALSE

the two major type-I interferons are produced by virus infected cells within A FEW HOURS of viral invasion.

26
Q

Type-I interferons released by virus infeced cells, cause which of the following :

a. inhibition of DNA replication in virus infected cells
b. increased MHC class 1 expression
c. activation of NK cells
d. all of the above

A

d. all of the above

27
Q

Define autocrine

A

cell secreted substance that acts on the same cell

28
Q

Define paracrine

A

cell secreted substance that acts on adjacent cells

29
Q

Which of the following is not a characteristic of typeII interferon : IFN gamma ?

a. labile at pH 2
b. does not demonstates host specificity
c. produced by antigen stimulated T cells and NK cells

A

b. does not demonstates host specificity

DOES demonstrate host specific immunity

30
Q

Which of the following is NOT a characteristic of typeIII interferons?

a. recently discovered
b. primary function is immunoregulation
c. expressed in response to viral infections
d. all of the above are characteristic

A

d. all of the above are characteristic

there are at least 3 types
IFN-gamma 1,2,3

31
Q

T/F cells utilize small, interfering RNA molecules to silence genes to potentially interfere with virus replication

A

True.

this is known as gene silencing.

cells use this mechanism to disrupt virus replication through production of RNAi that are complementary to specific viral genes.

32
Q

Adaptive immunity includes :

a. adaptive and humoral components
b. cellular and adaptive components
c. humoral and cellular components

A

c. humoral and cellular components

33
Q

Humoral immunity is mediated principally by ?

a. antibodies released from B lymphocytes
b. antigens
c. antibodies released from T cells

A

a. antibodies released from B lymphocytes

34
Q

Cellular immunity is mediated by ?

a. B lymphocytes
b. T lymphocytes

A

b. T lymphocytes

35
Q

T/F Adaptive immunity acts quickly, within hours

A

FALSE.

adaptive immunity is antigen specific, and takes several days to develop.

36
Q

T/F adaptive immunity stimulates long-term memory after infection

A

True

37
Q

T/F Internal viral antigens elicit humoral and CMI responses.

A

FALSE
SURFACE viral antigens elicit humoral AND CMI responses.

INTERNAL antigens elicit CMI response

38
Q

Define granulocytosis

A

presence in peripheral blood of an increased number of granulocytes (neutrophils, eosinophils, basophils, mast cells)

39
Q

Viral infections usually

a. provoke granulocytosis
b. do not provoke granulocytosis

A

b. do not provoke granulocytosis

40
Q

T/F virus capsid and envelope proteins are antigenic

A

true

41
Q

Antibodies may be directed against :

a. virus capsid
b. virus envelope
c. virus proteins on infected cells
d. all of the above

A

d. all of the above

42
Q

Define virus neutralization

A

neutralizing antibodies prevent virus attachment and entry into host cells. they bind to the viral capsid or host envelope

43
Q

What is opsonization?

A

coating virions with antibodies. antibody coated virion is recognized and phagocytosed by macrophages or neutrophils

44
Q

Clumping of viruses _____ the number of viral particles available for cell invasion.

a. increases
b. decreases

A

b. decreases

can be beneficial.

for example : parvovirus B19 oponisation and immune complex formation so no virus is left free

45
Q

Which of the following can activate the complement system?

a. opsonization
b. chemotaxis
c. lysis
d. agglutination
d. all of the above

A

d. all of the above

46
Q

opsonization :

a. attracts macrophages and neutrophils
b. ruptures membranes of foreign cells
c. enhances phagocytosis of antigens
d. binds pathogens togther

A

c. enhances phagocytosis of antigens

47
Q

Chemotaxis :

a. attracts macrophages and neutrophils
b. ruptures membranes of foreign cells
c. enhances phagocytosis of antigens
d. binds pathogens togther

A

a. attracts macrophages and neutrophils

48
Q

Lysis

a. attracts macrophages and neutrophils
b. ruptures membranes of foreign cells
c. enhances phagocytosis of antigens
d. binds pathogens togther

A

b. ruptures membranes of foreign cells

49
Q

Agglutination

a. attracts macrophages and neutrophils
b. ruptures membranes of foreign cells
c. enhances phagocytosis of antigens
d. binds pathogens togther

A

d. binds pathogens togther

50
Q

In antibody-dependent cell-mediated cytotoxicity, host cells are destroyed by :

a. macrophags
b. NK cells
c. complement
d. all of the above

A

d. all of the above

51
Q

In cell mediated immunity, which of the following is NOT caused by helper T cells?

a. activation of macrophages
b. inflammation
c. killing of infected cell
d. stimulation of B lymphocytes

A

c. killing of infected cell

would be caused by CD8+ cytotoxic T cell

52
Q

In cell mediated immunity, which of the following is caused by CD8+?

a. activation of macrophages
b. inflammation
c. killing of infected cell
d. stimulation of B lymphocytes

A

c. killing of infected cell

53
Q

Cytotoxic T lymphocytes are associated with ?

a. MHC class I
b. MHC class II

A

a. MHC class I

54
Q

What are perforins?

A

pore-forming proteins. released by CTL, when CTL binds to the infected cell

55
Q

In cell mediated immunity, What passes through the pores created in the infected cell to activate the caspase enzyme that leads to apoptosis of the infected cell?

a. perforins
b. chemokines
c. CD4
d. granzymes

A

d. granzymes

56
Q

Define antigenic plasticity

A

rapid changes in structure of viral antigen. due to changes in antigen structure, the virus may become resistant to immunity generated by previous infection.

57
Q

Which of the following would NOT cause antigenic plasticity :

a. mutation
b. reassortment
c. apoptosis
d. recombination

A

c. apoptosis

58
Q

T/F antigenic plasticity of a virus is usually beneficial to the host.

A

FALSE

T/F antigenic plasticity of a virus is usually NOT beneficial to the host.

due to change in antigen structure, the virus may become resistant to immunity generated by previous infection….bad for the host!

59
Q

What is antigenic multiplicity?

a. antigenic variants with high cross reactivity
b. antigenic variants with little or no cross reactivity

A

b. antigenic variants with little or no cross reactivity

ex : there are more than 100 serotypes of rhinoviruses which are antigenically different from eachother. SO immunity against one serotype may not work against the other variants

60
Q

What two viruses produce caspase inhibitors that protect the infected cells against death and allow virus replication to be completed?

a. parvo and retrovirus
b. retrovirus and poxvirus
c. HIV and parvo
d. poxvirus and herpes

A

d. poxvirus and herpes

virology (8 decks)

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