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Virology > Week 5 > Flashcards

Week 5 Flashcards

1
Q

Which of the following could be true if a person had shingles on their 60s?
- VSV might not be detectable in this person’s body fluid by antibody prior to the occuring of shingles
- The person might never have chickenpox prior to the occuring of shingles
- The person has never been infected by VSV prior to the occuring of shingles
- The person was taking immunosuppressant medicine recently

A
  • VSV might not be detectable in this person’s body fluid by antibody prior to the occuring of shingles
  • The person might never have chickenpox prior to the occuring of shingles
  • The person was taking immunosuppressant medicine recently
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2
Q

The viral gene coding for a protein involved in HSV genome packaging most likely belongs to
A. immediate early genes (IE)
B. early genes (E)
C. late genes (L)

A

B. early genes (E)

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3
Q

The proteins found in HSV tegument most likely have a prefix of
A. “g”
B. “VP”

A

B. “VP”

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4
Q

What are 8 human herpesviruses?

A
  1. Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2)
  2. Varicella-zoster virus (VZV)
  3. Epstein-Barr virus (EBV)
  4. Cytomegalovirus
  5. Herpesvirus 6A and 6B
  6. Herpesvirus 7
  7. Kaposi’s sarcoma-associated herpesvirus
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5
Q

Once infected, herpes virus remains as (______) infections for the lifetime of the host.

A

persistent

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6
Q

What is one way latent infections can become reactivated?

A
  • immunocompromised host
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7
Q

T/F. Both primary and reactivated herpesvirus infections can result in disease or be asymptomatic.

A

True

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8
Q

In HSV-1 and HSV-2, where can the virus hide to later establish latent infections?
A. epithelial cells
B. mucosal membranes
C. neurons

A

C. neurons

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9
Q

What are two ways a virus establishes a latent infection and which one is more stable (Why)?

A
  1. Genome integration
    - virus DNA integrated into cell chromosome genome and then into the genome of the host cell
    - MOST STABLE !!
  2. Extra chromosome
    - virus is present as multiple copies, extra chromosome
    - LESS STABLE bc might not be passed on
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10
Q

List the three types of productive infection.

A
  1. symptomatic
  2. asymptomatic
  3. death
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11
Q

Typically, HSV-1 infects (_____) and HSV-2 infects (_____).
A. face (lips); genitals (sexually transmitted)
B. genitals (sexually transmitted); face (lips)

A

A. face (lips); genitals (sexually transmitted)

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12
Q

T/F. The majority of genital herpes infections produce either atypical or no symptoms, only a minority of cases are recognized.

A

True

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13
Q

Varicella is the disease but (______) is the virus.

A

Varicella-zoster virus (VZV)

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14
Q

What does the latent infection of varicella (chickenpox) cause?

A

Shingles
- stays as an extra chromosome

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15
Q

Is VZV easy to detect in the lab to understand transmission?

A

No, there is no clear information

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16
Q

Shingles may develop in any age group, but you are more susceptible if:

A
  • older than 60
  • had chickenpox before age 1
  • weakened immune system
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17
Q

Does vaccination yield poor or strong immunization against chickenpox versus someone that had it before with no vaccination?

A

poor

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18
Q

What would be true if someone had shingles in their 60s? Select all that apply.
A. VZV might not be detectable in this person’s body fluid by antibody prior to the occurring of shingles
B. might have never had chickenpox prior
C. person never infected by VSV prior
D. person was taking immunosuppresants

A

A. VZV might not be detectable in this person’s body fluid by antibody prior to the occurring of shingles
B. might have never had chickenpox prior
D. person was taking immunosuppresants

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19
Q

How is the Epstein-Barr virus transmitted?

A

Saliva

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20
Q

In EBV, (_____) cells are infected first then the infection spreads to (_____) cells.

A

epithelial cells; B-cells

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21
Q

How is the human cytomegalovirus (CMV) transmitted?

A

Sexually

22
Q

How was human herpes 7 virus first isolated?

A

culture of CD4 cells

23
Q

What 3 distinct structures are complex virions composed of?

A
  1. capsid
  2. tegument (matrix)
  3. envelope
24
Q

Fill in the following about the herpes virion.
Genome:
Capsid:
Tegument:
Envelope:

A

Genome: linear dsDNA
Capsid: icosahedral surrounded by tegument
Tegument: viral matrix, lines the space between the envelope and nucleocapsid
Envelope: contains a large number of spikes

25
Q

The proteins found in HSV tegument most likely have a prefix of:
A. VP
B. g

A

A. VP

26
Q

In HSV-1, what are the most abundant proteins in the capsid and tegument?

A
  • VP5
  • VP16
27
Q

Where do herpesviruses gain their envelope from?
A. plasma membrane
B. golgi apparatus
C. de nova synthesis

A

B. golgi apparatus

28
Q

If a viral protein is called gB, where do you normally find them?
A. capsid
B. inside capsid
C. on viral envelope

A

C. on viral envelope

29
Q

What primary receptor does HSV-1 virion bind to before the main receptor?

A

heparan sulphate

30
Q

Explain the steps of how HSV-1 DNA is transported.

A
  1. the nucleocapsid and tegument proteins are released into the cytoplasm
  2. the nucleocapsid is rapidly transported with dynein along microtubules to the nuclear pore area
  3. The virus DNA is released into the nucleus where the linear molecule is converted into a covalently closed circular molecule (cccDNA)
31
Q

List the functions of tegument proteins.

A
  • down-regulation of host DNA, RNA
  • vhs (virion host shutoff) protein degrades cell mRNA
  • activation of virus genes
32
Q

Herpesvirus genes are expressed in which three phases?

A

Immediate Early (IE): need to make own transcription factor, make protein first

Early (E): virus DNA replication

Late (L): structural proteins

33
Q

LATs are…

A

virus RNAs synthesized during latency
- role in inhibiting apoptosis to allow survival of neuron with latent HSV-1 infection

34
Q

List 3 characteristics of parvoviruses.

A
  • Icosahedral
  • linear (-)ssDNA or (+)ssDNA
  • smallest known virus
  • hosts: mammals, birds, insects
35
Q

What are dependoviruses?

A
  • are defective
  • cannot infect host on its own
  • only replicates when the host cell is co-infected with helper virus (adenovirus)
36
Q

Do autonomous parvoviruses require helper viruses for replication?

A

NO, can replicate on its own

37
Q

T/F. All dependoviruses absolutely require the help of an adenovirus.

A

False.
- Other DNA viruses may act as helpers
- some dependoviruses replicate in the absence of a helper under certain conditions

38
Q

The blood from donor #1 has no detectable virus in an infectivity assay, but when the blood is mixed with blood that is known to have adenovirus from donor #2, then an infection from a second virus can be detected. What could be the reason?
A. Donor #1 has the dependovirus not replicated before mixing
B. Donor #2 has the dependovirus not replicated before mixing

A

A. Donor #1 has the dependovirus not replicated before mixing

39
Q

Autonomous parvoviruses can infect without any signs and symptoms. This can result in a disease called….

A

fifth disease (common in children)

40
Q

T/F. There is a vaccine and medicine that can prevent parvovirus B19 infection.

A

False. There is no vaccine and medicine that can prevent parvovirus B19 infection.

41
Q

In parvoviruses, the 5’ end has which covalently linked protein molecule that is involved in replication and present on the surface of the virion?

A

Rep or NS1

42
Q

Match the following genome structures:
1. Inverted repeats at the termini
2. unique sequences at the termini

  • produces equal number of (+) and (-_ strands of virus DNA with ITRs
  • folded back/complementary to itself
  • unequal strands of (+) and (-) strands of virus DNA
A
  1. Inverted repeats at the termini
    - produces equal number of (+) and (-_ strands of virus DNA with ITRs
    - folded back/complementary to itself
  2. unique sequences at the termini
    - unequal strands of (+) and (-) strands of virus DNA
43
Q

Assuming that all the cells listed below are permissive cells to parvovirus, the virus is more likely to replicate in
A. normal somatic cells
B. cancer cells

A

B. cancer cells

44
Q

Parvoviruses are more likely to replicate in cells at which cell cycle phase?
A. G0 phase
B. G1 phase
C. S phase
D. M phase

A

C. S phase

45
Q

Why is parvovirus DNA replication restricted to the S phase?

A
  • some cell proteins like DNA polymerase are only available during S phase
46
Q

List the steps of attachment and entry of the parvovirus into the host cell.

A
  1. Binds to primary receptor and 1 or more coreceptors
    - Rep protein is removed from the 5’ end of viral genome while virion is STILL ON SURFACE
    - entry through clathrin-endocytosis
  2. transported to the nucleus along microtubules
  3. Nuclear localization signals found on VP1 capsid proteins and taken into nucleus
    - virus genome released at nuclear pore before or released after virion is transported through
47
Q

The cell RNA polymerase II transcribes virus genes. The transcripts undergo splicing to produce larger mRNA and smaller mRNA. What do the different RNAs encode for?

A

larger mRNA: non-structural proteins
- Rep proteins
- (IE) proteins
smaller mRNA: structural proteins
- (L) proteins

48
Q

Explain this genome replication and assembly process.

A
  1. Rolling hairpin replication
  2. Procapsids constructed from structural proteins
    - genome copy is packed inside procapsid
    - genome enters via one of the 12 pores of the procapsid
49
Q

If a cell with latent dependoviral genome becomes infected with appropriate helper virus, what is the result?

A

Productive infection

50
Q

How is latent infection established in parvoviruses?

A

Integration of the viral dsDNA genome into a cell chromosome
- in human cells the virus DNA is inserted at chromosome 19

Virology (5 decks)

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