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MCIM 224 > 12 Viruses (4) > Flashcards

12 Viruses (4) Flashcards

1
Q

Where do respiratory tract viruses tend to replicate?

A

Cells of ANY part of the respiratory tract

from the nasal passages down to the lower lung bronchioles

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2
Q

T or F: Respiratory viruses are usually not a problem in developing countries, but a big concern in the developed world due to resistance.

A

F

Low mortality rate in the developed world due to respiratory viruses, but a big concern in developing countries

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3
Q

Respiratory tract viruses tend to have a _______ distribution.

A

seasonal

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4
Q

Name two ways respiratory viruses can be transmitted.

A
  1. Inhalation of aerosols

2. Contact w/ contaminated surfaces

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5
Q

Name a v. popular respiratory virus.

A

Influenza virus

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6
Q

What is the structure of the influenza virus?

A

Enveloped RNA virus w/ a “segmented” genome

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7
Q

What’re the two kinds of spike proteins on the envelope of influenza?

A
  1. Neuraminidase (N)

2. Hemagglutinin (H)

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8
Q

What does neuraminidase (N) (type of Flu spike protein) do? (2)

A
  1. DEGRADES mucus layer on respiratory epithelial cells > allows virus to reach cell surface
  2. Helps in the release of newly-formed mature Flu viruses from host cells
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9
Q

What does hemagglutinin (H) (type of Flu spike protein) do?

A

ATTACHES to receptors on respiratory tract epithelial cells

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10
Q

T or F: Either the neuraminidase OR the hemagglutinin of the influenza virus is enough for the virus to infiltrate host cells.

A

F

BOTH are needed

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11
Q

T or F: Both neuraminidase AND hemagglutinin are needed for the influenza virus to be released from the host cell.

A

F

Only neuraminidase is needed for the release of influenza viruses from the host cell.

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12
Q

Three types of influenza virus?

A

Type A
Type B
Type C

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13
Q

What is the most common type of influenza virus?

A

Type A

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14
Q

Which type of influenza causes the most severe symptoms?

A

Type A

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15
Q

What’s the most MILD type of influenza?

A

Type C

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16
Q

Which influenza type has H and N types?

A

Type A

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17
Q

If a patient is infected w/ H5N1, which type of influenza does he have?

A

Type A (only type A has H and N designations)

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18
Q

Which influenza type has a broad host range?

A

Type A

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19
Q

Which influenza type has a limited host range (humans and some marine mammals only)?

A

Type B

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20
Q

What is antigenic drifting?

A

When, during virus replication, random mutations occur in H or N genes, resulting in MINOR changes in H or N surface spike proteins.

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21
Q

What is antigenic shifting?

A

Two viruses with different subtypes infect the same host at the same time > H and N genes of flu’s SEGMENTED genome re-assort (mix) > progeny viruses are hybrids of the two original viruses (i.e. NEW SUBTYPE)

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22
Q

What’re the two ways flu viruses can evolve over time?

A
  1. Antigenic shifting

2. Antigenic drifting

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23
Q

Random mutations occurring in influenza’s genome is called…

a. antigenic drifting
b. antigenic shifting

A

a.

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24
Q

Genetic shuffling b/w the genomes of two influenza viruses is called…

a. antigenic drifting
b. antigenic shifting

A

b.

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25
Q

Different strains of influenza are brought about through…

a. antigenic drifting
b. antigenic shifting

A

a.

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26
Q

Different subtypes of influenza A are brought about by…

a. antigenic drifting
b. antigenic shifting

A

b.

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27
Q

Influenza A enters and replicates in which cells?

A

Epithelial cells of the upper and lower respiratory tract

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28
Q

What’s the incubation period of influenza A viruses?

A

1-3 days before onset of symptoms

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29
Q

How long before the onset of symptoms is one contagious with the flu virus? How long after the symptoms are gone?

A

1 day before symptoms

up to 5 days after symptoms

30
Q

What is the major complication associated w/ influenza infections?

A

Secondary bacterial infections in the lungs

31
Q

Do I have the flu or a cold?

I have a high fever.

A

Flu

32
Q

Do I have the flu or a cold?

I have a headache.

A

Flu

33
Q

Do I have the flu or a cold?

I don’t have any aches or pains.

A

Cold

34
Q

Do I have the flu or a cold?

I have extreme fatigue

A

Flu

35
Q

Do I have the flu or a cold?

I have a runny nose.

A

Can be either the flu or a cold.

36
Q

Do I have the flu or a cold?

I have a sore throat.

A

Can be either the flu or a cold.

37
Q

How is lab diagnosis of the influenza virus conducted?

A

Nasopharyngeal swab (far back into nasopharyngeal area) > Nucleic acid amplification test (PCR) performed for identification of viral nucleic acid

38
Q

What is usually the treatment plan for a person suffering from an influenza infection? (4)

A
  1. Rest
  2. Fever-relief
  3. Nutrition
  4. Hydration
39
Q

What’re two antivirals that’re used in exceptional circumstances to battle a flu infection? How do they work?

A
  1. oseltamivir
  2. zanamivir

They block neuraminidase activity of influenza type A only.

40
Q

Oseltamivir and zanamivir reduce the risk of infection by the flu by ___%.

A

75%

41
Q

Protective immunity against the flu is achieved when you have antibodies against THIS flu surface spike protein.

A

H protein (having N antibodies as well would be ideal, but not required for protective immunity)

42
Q

What’s the problem with immunity against the flu?

A

Immunity is STRAIN-SPECIFIC

43
Q

T or F: If you’re immune against H1N1, then you’re also protected against H3N2.

A

F

44
Q

The flu vaccine contains either…(2)

A
  1. killed whole virus, or

2. H and N proteins

45
Q

How effective is the flu vaccine at protecting against the flu?

A

50-60%

46
Q

After getting the flu shot, how long before antibodies against the flu are fully developed?

A

~2 weeks

47
Q

How long does a flu vaccination last?

A

~1 year

48
Q

What’re 2 reasons the protection against the flu virus with the vaccine is only 50-60%?

A
  1. The flu virus may CHANGE (subtype/strain variations)

2. Diff pt pops respond differently to the vaccine

49
Q

Why do inds need to get the flu vaccine each year?

A
  1. Antibodies from last year are mostly gone

2. New influenza strains in circulation that weren’t included in prev year’s vaccine fmlation

50
Q

Name a virus responsible for a new, emerging viral disease.

A

Ebola virus

51
Q

Structure of the ebola virus?

A

Enveloped RNA virus w/ a “pleomorphic” (i.e. inconsistent) morphology

52
Q

Where is Ebola virus found naturally?

A

African continent

53
Q

Ebola virus is an example of a “_____ _____ virus”

A

hemorrhagic fever

54
Q

How is Ebola virus transmitted?

A

Blood or bodily fluids

55
Q

Which blood cell type initially gets infected by Ebola virus?

A

White blood cells

56
Q

How does Ebola virus spread throughout the body?

A

Lymphatic system

57
Q

What’re three things that the Ebola virus does to the body?(3)

A
  1. Increases vascular permeability (thus, blood vessels leak)
  2. Interferes w/ coagulation system
  3. Dysregulation of the immune system
58
Q

T or F: Ebola virus eventually causes multi-organ failure, leading to death.

A

T

59
Q

How early can symptoms of Ebola infection show up after being infected? On avg, how many days does it take for symptoms to appear after infection?

A

As early as 2 days after being infected

Avg: 8 days after being infected

60
Q

T or F: Ebola virus infections progress very slowly.

A

F

Pts worsen RAPIDLY after the onset of symptoms

61
Q

What anti-virals can be used to treat Ebola virus?

A

None available; only supportive care is possible

62
Q

What 5 things can be done in the supportive care of a person suffering from an Ebola virus infection?

A
  1. Maintain ELECTROLYTE balance
  2. Aggressive FLUID replacement
  3. Maintain BP and oxygenation
  4. Nutritional support
  5. Pain ctrl
63
Q

What do we know about “emerging” diseases? (4)

A
  1. They usually start as “zoonotic” diseases
  2. International outbreaks = possible
  3. Outbreaks are sustained by human-human contact
  4. Recognizing and fighting “new” viral diseases = challenging
64
Q

What type of microbe will likely cause an emerging infectious disease in the future?

a. bacteria
b. fungi
c. viruses

A

c. viruses

65
Q

What three characteristics about a virus make it compatible w/ the def’n of something that is “alive”?

A
  1. Contain nucleic acids, proteins, and s.times lipids and enzymes
  2. They can “reproduce”
  3. Their genes mutate and evolve
66
Q

What three characteristics about a virus make it incompatible w/ the def’n of something that is “alive”?

A
  1. No cellular organization
  2. Totally inert outside of host cell
  3. Replication is via self-assembly of pre-formed components
67
Q

What’re 3 hypotheses regarding the origins of viruses?

A
  1. “Retrograde” evolution (cells continuously lost fns until they became completely dependent on another host)
  2. Cellular origin (combos of cellular macromolecules eventually gained the ability to self-assemble and replicate
  3. Parallel evolution w/ cells when life first began.
68
Q

What microbe may be the “missing link” b/w the cellular and viral worlds?

A

Mimivirus (“mimicking microbe”)

69
Q

How many genes does a mimivirus have?

A

~900 genes

70
Q

What percent of human genetic material originates from viruses?

A

8%(!!)

MCIM 224 (25 decks)

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