12 Viruses (4)

Question 1

Where do respiratory tract viruses tend to replicate?

Answer 1

Cells of ANY part of the respiratory tract

from the nasal passages down to the lower lung bronchioles

Question 2

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

Answer 2

F

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

Question 3

Respiratory tract viruses tend to have a _______ distribution.

Answer 3

seasonal

Question 4

Name two ways respiratory viruses can be transmitted.

Answer 4

1. Inhalation of aerosols

2. Contact w/ contaminated surfaces

Question 5

Name a v. popular respiratory virus.

Answer 5

Influenza virus

Question 6

What is the structure of the influenza virus?

Answer 6

Enveloped RNA virus w/ a “segmented” genome

Question 7

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

Answer 7

1. Neuraminidase (N)

2. Hemagglutinin (H)

Question 8

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

Answer 8

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

Question 9

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

Answer 9

ATTACHES to receptors on respiratory tract epithelial cells

Question 10

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

Answer 10

F

BOTH are needed

Question 11

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

Answer 11

F

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

Question 12

Three types of influenza virus?

Answer 12

Type A
Type B
Type C

Question 13

What is the most common type of influenza virus?

Answer 13

Type A

Question 14

Which type of influenza causes the most severe symptoms?

Answer 14

Type A

Question 15

What’s the most MILD type of influenza?

Answer 15

Type C

Question 16

Which influenza type has H and N types?

Answer 16

Type A

Question 17

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

Answer 17

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

Question 18

Which influenza type has a broad host range?

Answer 18

Type A

Question 19

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

Answer 19

Type B

Question 20

What is antigenic drifting?

Answer 20

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

Question 21

What is antigenic shifting?

Answer 21

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)

Question 22

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

Answer 22

1. Antigenic shifting

2. Antigenic drifting

Question 23

Random mutations occurring in influenza’s genome is called…

a. antigenic drifting
b. antigenic shifting

Answer 23

a.

Question 24

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

a. antigenic drifting
b. antigenic shifting

Answer 24

b.

Question 25

Different strains of influenza are brought about through... a. antigenic drifting b. antigenic shifting

Answer 25

a.

Question 26

Different subtypes of influenza A are brought about by... a. antigenic drifting b. antigenic shifting

Answer 26

b.

Question 27

Influenza A enters and replicates in which cells?

Answer 27

Epithelial cells of the upper and lower respiratory tract

Question 28

What's the incubation period of influenza A viruses?

Answer 28

1-3 days before onset of symptoms

Question 29

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

Answer 29

1 day before symptoms up to 5 days after symptoms

Question 30

What is the major complication associated w/ influenza infections?

Answer 30

Secondary bacterial infections in the lungs

Question 31

Do I have the flu or a cold? I have a high fever.

Answer 31

Flu

Question 32

Do I have the flu or a cold? I have a headache.

Answer 32

Flu

Question 33

Do I have the flu or a cold? I don't have any aches or pains.

Answer 33

Cold

Question 34

Do I have the flu or a cold? I have extreme fatigue

Answer 34

Flu

Question 35

Do I have the flu or a cold? I have a runny nose.

Answer 35

Can be either the flu or a cold.

Question 36

Do I have the flu or a cold? I have a sore throat.

Answer 36

Can be either the flu or a cold.

Question 37

How is lab diagnosis of the influenza virus conducted?

Answer 37

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

Question 38

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

Answer 38

1. Rest 2. Fever-relief 3. Nutrition 4. Hydration

Question 39

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

Answer 39

1. oseltamivir 2. zanamivir They block neuraminidase activity of influenza type A only.

Question 40

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

Answer 40

75%

Question 41

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

Answer 41

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

Question 42

What's the problem with immunity against the flu?

Answer 42

Immunity is STRAIN-SPECIFIC

Question 43

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

Answer 43

F

Question 44

The flu vaccine contains either...(2)

Answer 44

1. killed whole virus, or | 2. H and N proteins

Question 45

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

Answer 45

50-60%

Question 46

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

Answer 46

~2 weeks

Question 47

How long does a flu vaccination last?

Answer 47

~1 year

Question 48

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

Answer 48

1. The flu virus may CHANGE (subtype/strain variations) | 2. Diff pt pops respond differently to the vaccine

Question 49

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

Answer 49

1. Antibodies from last year are mostly gone | 2. New influenza strains in circulation that weren't included in prev year's vaccine fmlation

Question 50

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

Answer 50

Ebola virus

Question 51

Structure of the ebola virus?

Answer 51

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

Question 52

Where is Ebola virus found naturally?

Answer 52

African continent

Question 53

Ebola virus is an example of a "_____ _____ virus"

Answer 53

hemorrhagic fever

Question 54

How is Ebola virus transmitted?

Answer 54

Blood or bodily fluids

Question 55

Which blood cell type initially gets infected by Ebola virus?

Answer 55

White blood cells

Question 56

How does Ebola virus spread throughout the body?

Answer 56

Lymphatic system

Question 57

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

Answer 57

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

Question 58

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

Answer 58

T

Question 59

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?

Answer 59

As early as 2 days after being infected Avg: 8 days after being infected

Question 60

T or F: Ebola virus infections progress very slowly.

Answer 60

F Pts worsen RAPIDLY after the onset of symptoms

Question 61

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

Answer 61

None available; only supportive care is possible

Question 62

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

Answer 62

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

Question 63

What do we know about "emerging" diseases? (4)

Answer 63

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

Question 64

What type of microbe will likely cause an emerging infectious disease in the future? a. bacteria b. fungi c. viruses

Answer 64

c. viruses

Question 65

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

Answer 65

1. Contain nucleic acids, proteins, and s.times lipids and enzymes 2. They can "reproduce" 3. Their genes mutate and evolve

Question 66

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

Answer 66

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

Question 67

What're 3 hypotheses regarding the origins of viruses?

Answer 67

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.

Question 68

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

Answer 68

Mimivirus ("mimicking microbe")

Question 69

How many genes does a mimivirus have?

Answer 69

~900 genes

Question 70

What percent of human genetic material originates from viruses?

Answer 70

8%(!!)