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MCIM 224 > 10 Viruses (2) > Flashcards

10 Viruses (2) Flashcards

1
Q

What’re viruses?

A

Non-cellular agents that cannot reproduce independently

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2
Q

Very general structure of a virus?

A

Nucleic acid surrounded by a protein (capsid) coat

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3
Q

4 types of viral outcomes/infections?

A
  1. Lytic (acute) infection
  2. Persistent (chronic) infection
  3. Latent infection
  4. Oncogenic infection (“Host Cell Transformation”)
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4
Q

Life cycle of all viruses involves…

A
  1. Adsorption
  2. Penetration/uncoating
  3. Gene expression
  4. Assembly
  5. Release
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5
Q

List three ways a virus can cause damage to the host tissue.

A
  1. Viral replication can cause host cell LYSIS
  2. Cell metabolism is altered by virus infection > impaired fn
  3. Viral proteins get inserted into host cell membrane > cell appears foreign to immune sys > cell gets attacked
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6
Q

T or F: Tissue damage that’s caused by viruses often make the host less susceptible to infections by other microbes.

A

F

Tissue damage that’s caused by viruses often make the host MORE susceptible to infections by other microbes

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7
Q

T or F: Diff classes of viruses often infect the SAME organ or tissue.

A

T

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8
Q

T or F: Almost every body system is susceptible to viral infection

A

T

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9
Q

T or F: Viruses infect the site at which they first make contact with the host.

A

F

Not necessarily true. Infection can occur at sites distant from site of first contact.

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10
Q

How can viruses be spread throughout the body? (2)

A
  1. Blood

2. Lymph

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11
Q

What must be present for viruses to initially infect cells?

A

Suitable cell receptors

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12
Q

T or F: The site of virus entry does not always equate to the site of disease symptoms.

A

T

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13
Q

Why is it important to identify the specific virus causing an infection? (3)

A
  1. Rules out other microbes
  2. Help with patient management
  3. Infection ctrl (inds w/ the same infection can be kept in the same place)
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14
Q

Diagnostic challenges w/ viral infections? (3)

A
  1. Viral infection symptoms sometimes similar to those caused by other microbes
  2. Diff viruses often produce the SAME symptoms OR a single virus can cause a range of diff symptoms
  3. Virus diagnostic methods are v. diff from those of bacteria and fungi (need a living cell; agar plates, etc., aren’t appropriate for viruses)
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15
Q

Three steps to diagnosing viral infections?

A
  1. Assess clinical picture (i.e. are the pt’s symptoms and history consistent w/ a viral infection?)
  2. Collect appropriate specimen
  3. Lab testing
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16
Q

What’re the two types of lab tests for viruses?

A
  1. Direct tests

2. Indirect tests

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17
Q

If I’m testing for the presence of the virus itself, then I’m using a(n) ____ laboratory test.

A

direct

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18
Q

If I’m testing for the body’s immune response to the virus, then I’m using a(n) ____ laboratory test.

A

indirect

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19
Q

Name the two specific direct lab tests used in viral diagnosis.

A
  1. Nucleic Acid Amplification tests (NAATs)

2. Direct Fluorescent Antibody (DFA) tests

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20
Q

What does one look for during a NAAT (Nucleic Acid Amplification test)?

A

One looks for the virus’s DNA or RNA in the clinical specimen

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21
Q

NAATs (Nucleic Acid Amplification tests) utilize what kind of technology?

A

Polymerase Chain Reaction (PCR) technology

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22
Q

What does one look for in a Direct Fluorescent Antibody (DFA) test?

A

One looks for virus-infected cells by seeing if any of them (the infected cell, not the virus) are bound by antibodies that have been tagged w/ a fluorescent dye

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23
Q

What is the advantage of using NAATs over DFA tests?

A

Nucleic Acid Amplification tests are much more sensitive than Direct Fluorescent Antibody tests (i.e. We need LOTS of infected cells for DFA to be feasible)

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24
Q

In NAATs, you’re looking for…

In DFA tests, you’re looking for…

A

Viral DNA/RNA

Virus-infected cells

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25
Q

What indirect test is used in lab viral diagnosis?

A

Serology tests

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26
Q

What does one look for in serology tests?

A

One looks for anti-viral antibodies in the pt’s blood

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27
Q

What specific test is used to detect anti-viral antibodies in serology testing?

A

ELISA tests

Enzyme-Linked Immunosorbent Assay

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28
Q

Why are you not automatically considered to be currently infected if you’re found to have antibodies for a specific virus?

A

Because antibodies can persist for a long time, even after the virus is long gone

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29
Q

T or F: Serology tests are useful at any time to indicate the presence of an infection

A

F

Serology tests aren’t useful in the early stages of an infection since your body hasn’t had enough time to make antibodies against the virus

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30
Q

What types of skin lesions are commonly caused by viruses that infect the skin?

A
  1. Rashes
  2. Fluid-filled blisters
  3. Warts
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31
Q

2 routes of transmission for viruses that infect the skin:

A
  1. Direct contact (e.g. w/ a blister)

2. Inhalation of respiratory secretion (it migrates to epithelial surfaces)

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32
Q

What are some skin viruses able to do?

A

Migrate further and enter the CNS

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33
Q

Name two viruses that’re able to migrate from skin epithelia cells into nerves.

A
  1. Herpes

2. Varicella

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34
Q

HSV is a(n) _____ virus

a. enveloped
b. naked
c. DNA
d. RNA
e. both a and c
f. both a and d
g. both b and c
h. both b and d

A

e.

HSV = enveloped, DNA virus

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35
Q

How does one acquire HSV?

A

DIRECT contact w/ someone who has an active HSV lesion

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36
Q

Initially, HSV is THIS type of viral infection when it enters epithelial cells.

A

Lytic (acute) infection

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37
Q

What kind of skin lesions are caused by HSV?

A

Fluid-filled blisters

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38
Q

To where can HSV spread?

A

Nearby sensory nerves

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39
Q

What does the HSV virus do when it reaches the nerve cell? What kind of infection results?

A

It enters the nucleus > its viral DNA gets inserted into the cell’s chromosome > it becomes a LATENT infection

40
Q

What’s the hypothesized purpose of HSV latency?

A

Protection from the immune system

41
Q

T or F: HSV genes can be reactivated by external stimuli, such as stress, trauma, fever, and sunlight.

A

T

42
Q

T or F: HSV eventually gets cleared by the immune system.

A

F

HSV persists for LIFE, switching b/w lytic and latent states

43
Q

HSV-1 usually causes three types of herpes infections:

A
  1. Oral herpes (“cold sores”)
  2. Herpes Keratitis
  3. Herpetic Whitlow
44
Q

Herpes keratitis is an HSV infection of the _____.

It occurs due to _____.

A

eyes (corneas, specifically)

autoinoculation

45
Q

Herpetic whitlow is an HSV infection of the ______.

A

fingers

46
Q

What percentage of adults have antibodies to HSV-1?

A

~65%

47
Q

THIS type of herpes infection is commonly contracted in contact sports.

A

Herpes gladiatorum

48
Q

What strain of herpes virus is most commonly associated w/ genital herpes?

A

HSV-2

49
Q

Genital herpes manifests itself as what?

A

Vesicular lesions in the genital area

50
Q

About 15% of HSV infections cause _____

A

encephalitis

51
Q

Adult encephalitis is mostly caused by THIS strain of HSV, while neonatal encephalitis is usually caused by THIS strain of HSV.

A

HSV-1 (adults)

HSV-2 (neonates)

52
Q

How does adult encephalitis develop from an HSV infection?

A

Latent HSV gets reactivated > instead of migrating to epithelial cells, it migrates backwards towards the brain

53
Q

HSV-induced encephalitis in adults is usually seen in these two pops:

A
  1. Elderly

2. Immunocompromised

54
Q

How do babies get infected initially?

A

A newborn can contract it from his mother if she has active genital HSV lesions during birth.

55
Q

How does the primary infection of HSV-2 manifest itself in newborns? How is neonatal encephalitis caused?

A

Widespread skin lesions.

The herpesvirus makes its way into the CNS > encephalitis results

56
Q

T or F: Neonatal encephalitis due to HSV-2 causes PERMANENT neurological damage or death.

A

T

57
Q

What should mothers who have active HSV lesions consider if they’re expecting to give birth?

A

C-section

58
Q

What type of test can rapidly test for HSV-1 or HSV-2?

A

NAATs (Nucleic acid amplification tests)

59
Q

HSV should be tested for in THIS if neurological symptoms are present.

A

CSF

60
Q

HSV should be tested for in THIS if vesicular lesions are present.

A

Fluid from the blisters

61
Q

What cures are available for HSV?

A

None

62
Q

What drugs are available for treating HSV?

A
  1. Acyclovir (and other “-cyclovir” drugs in general)
  2. Abreva (10% docosanol topical cream)
  3. Topical anesthetics
63
Q

How does acyclovir help with HSV outbreaks?

A

Shortens duration of lesions

64
Q

What drug is effective for HSV-induced encephalitis?

A

Acyclovir

65
Q

How does Abreva work?

A

Blocks entry of HSV into host cells

66
Q

How do topical anesthetics help w/ HSV outbreaks?

A

They reduce discomfort ONLY

67
Q

Why can HSV be destroyed by soap and water?

A

It’s an enveloped virus, so its lipid envelope can be disrupted by detergents

68
Q

Avoiding active HSV lesions is a good way to avoid spreading it and autoinoculation. However, this isn’t always feasible. Why?

A

Some active lesions are small, and thus not obvious.

69
Q

HPV is a(n) _____ virus

a. enveloped
b. naked
c. DNA
d. RNA
e. both a and c
f. both a and d
g. both b and c
h. both b and d

A

b. and c.

70
Q

HPV comprises over ____ “genotypes”

A

100

71
Q

Most common HPV infections manifest themselves as what?

A

warts (abnormal skin growths that project outward)

72
Q

Rarely, serious HPV infections can cause what? Where do they usually occur in men and women (if they occur at all)?

A

Cancer

In men: Oropharynx (throat)

In women: Cervix

73
Q

How is HPV transmitted?

A

Direct skin-to-skin contact

74
Q

Where amongst the skin layers does HPV specifically enter?

A

The basal layer (stratum basale) of the epidermis

75
Q

How does HPV work?

A

It causes the basal cells to divide more rapidly, and to continue dividing after they normally should have stopped

76
Q

What triggers the production and assembly of new HPV?

A

The MIGRATION of infected basal cells upward to skin surface

77
Q

About how many HPV particles per cell are present by the time the basal cell reaches the skin surface?

A

1000s

78
Q

HPV-infected epithelial cells form characteristic warts/papillomas. Why?

A

They divide more rapidly than non-infected cells

79
Q

HPV is an example of a(n) “______” virus bc it causes unctrled host cell growth.

A

“oncogenic”

80
Q

What occurs when HPV-infected epithelial cells die?

A

They release HPV onto the skin surface > new rounds of infection are initiated

81
Q

What effective anti-viral agents are there for HPV?

A

None

82
Q

Name 4 ways HPV-infected epithelial tissue can be killed?

A
  1. Caustic chemicals
  2. Cryogenic treatment (liquid nitrogen)
  3. Laser treatment
  4. Surgical removal
83
Q

Approximately ___% of skin warts spontaneously disappear within 6-18 months w/o treatment due the body’s immune sys response.

A

50%

84
Q

List the 4 HPV types that have a preference for infecting epithelial cells of the genital area:

A
  1. 6
  2. 11
  3. 16
  4. 18
85
Q

What HPV types are considered “low-risk” i.e. cause genital warts only

A

6, 11

86
Q

What HPV types are considered “high-risk” i.e. can cause cancer, in addition to genital warts

A

16, 18

87
Q

Why are high-risk HPV infections more likely to lead to cancer? (2)

A
  1. They cause far more rapid epidermal basal cell replication
  2. They interfere more w/ the host cell’s proteins that regulate cell growth and repair mutated DNA
88
Q

T or F: Presence of high-risk HPV is sufficient to cause cancer.

A

F

Other factors must be present

89
Q

How can HPV and cervical cancer be diagnosed?

A
  1. Pap test (looks for cervical cancer, not HPV specifically)
  2. “HPV PCR” test (looks for HPV specifically)

–>Ideally, both are done together

90
Q

About ___% of sexually-active men and women will acquire a genital HPV infection before the age of 50.

A

85%

91
Q

What three factors determine whether s.o. w/ genital warts caused by HPV will go on to develop cancer?

A
  1. HPV type (high- vs low-risk)
  2. DURATION of infection
  3. Presence of other poorly-defined FACTORS
92
Q

The vaccine against HPV is made by using what part of the HPV virus?

A

The CAPSID proteins = “Virus-like particles”

93
Q

Gardasil contains virus-like particles from which HPV types?

A

6, 11, 16, and 18

94
Q

Gardasil is approved for use in males and females b/w the ages of…

A

9-26 years

95
Q

Gardasil should be given BEFORE what?

A

The onset of sexual activity

96
Q

If the vaccine is almost 100% effective in preventing infection by high-risk HPV types, why is your protection vs. cervical cancer only 90%?

A

Because 10% of cervical cancers are caused by OTHER non-HPV stuff.

MCIM 224 (25 decks)

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