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Clinical Microbiology > Virology > Flashcards

Virology Flashcards

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Biology 101 flashcards
1
Q

Viruses cause ___% of human illness

A

80%

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2
Q

Can obligate intracellular parasites live outside a cellular host?

A

No

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3
Q

Can obligate intracellular parasites be treated or cured?

A

No, not with existing medical therapies

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4
Q

What are the smallest known pathogens?

A

Viroids

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5
Q

What are viroids? How do they replicate?

A

Naked, circular, single-stranded RNA molecules that do not encode protein yet replicate autonomously when introduced into host plants

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6
Q

A viral particle is a…

A

virion

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7
Q

What does a virion’s structure consist of?

A
  • Protein coat
  • Nucleic acid core
  • Envelope (occasionally)
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8
Q

In a laboratory setting, what are the three ways to replicate viruses?

A
  • Cell culture
  • Fertilized eggs
  • Living animals
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9
Q

Each virus capsid consists of…

A

identical protein units called capsomeres

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10
Q

The protein coat surround the nucleic acid core is called…

A

a capsid

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11
Q

Capsomeres bond together and give the capsid…

A

symmetry

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12
Q

What are the two basic patterns of self assembly of virus capsids?

A
  • Helical symmetry
  • Icosahedral symmetry
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13
Q

What is helical symmetry of a capsid?

A

Protein subunits and nucleic acid are arranged in a helix

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14
Q

What is icosahedral symmetry of a capsid?

A

Protein subunits assemble into a symmetric shell that covers the nucleic acid containing core

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15
Q

Viruses are characterized by their…

A

nucleic acid cores

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16
Q

The DNA and RNA is a virus’ core can be ___ or ___

A

ds (double stranded) or ss (single stranded)

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17
Q

If genetic information is used within a cell to produce the proteins needed for the cell to function, what is occurring?

A

Expression
Cell metabolizes and grows

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18
Q

If genetic information is being transferred horizontally between cells of the same generation, what is occurring?

A

Recombination
Recombinant cell with new combinations of genes

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19
Q

If genetic information is being transferred vertically to the next generation of cells, what is occurring?

A

Replication
Offspring cells produced

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20
Q

What is the most stable viral form/genome?

A

dsDNA genome

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21
Q

What is an example of a virus with dsDNA genome?

A

Herpesviridae

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22
Q

What viral form/genome is most prone to mutation?

A

+ssRNA genome

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23
Q

What is an example of a virus with +ssRNA genome?

A

Ebola virus

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24
Q

Many viruses that infect mammals are…

A

enveloped

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25
Q

All envelopes have…

A

a phospholipid bilayer

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26
Q

Envelopes arise from…

A

the plasma membrane of the infected host cell

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27
Q

If a virus does not have an envelope, how is it classified?

A

Naked

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28
Q

Is adenovirus naked or enveloped?

A

Naked

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29
Q

Is herpesvirus naked or enveloped?

A

Enveloped

30
Q

After a virion enters a host cell, its DNA is…

A

uncoated

31
Q

Once virion DNA is uncoated, a portion is transcribe, producing…

A

mRNA that encodes “early” viral proteins

32
Q

What occurs during biosynthesis of the virus?

A

Viral DNA is replicated and some viral proteins are made

33
Q

In late translation, ___ are synthesized

A

capsid proteins

34
Q

Once virions are mature, they are…

A

released

35
Q

What is a lytic infection?

A

Host cell fills with virions and bursts resulting in cell death

36
Q

What are the six steps of lytic infection?

A
  1. Attachment
  2. Penetration
  3. Uncoating
  4. Biosynthesis
  5. Maturation
  6. Release
37
Q

What is viral tropism?

A

Virus binds to specific receptors on host cell

38
Q

Some virions require ___ for successful attachment to a host cell

A

co-receptors

39
Q

What are the steps of virion penetration?

A
  • Adhesion of virus to host receptors
  • Engulfment into vesicle
  • Viral RNA is released from vesicle
40
Q

What is uncoating and where can it occur?

A

Removal of the capsid happens:
* at plasma membrane
* in the cytoplasm
* at the nuclear membrane

41
Q

After uncoating of viral DNA, ___ makes a DNA copy of the RNA, then uses the new DNA as a template to make complementary DNA strand.

A

reverse transcriptase

42
Q

Integration of a viral DNA ;copy into a host chromosome is called…

A

provirus

43
Q

Virion maturation involves moving newly made virions to specific sites in the cell for…

A
  • intracellular trafficking
  • assembly
44
Q

What is the most important part of virion assembly?

A

Placement of the viral genome inside the capsid

45
Q

Virion is assembled while…

A

the viral genome is being synthesized

46
Q

During virion assembly, the viral genome will be inserted into…

A

already formed capsids

47
Q

What are the two ways new virions can be released from cells?

A
  • Lysis (non-enveloped)
  • Budding (envoloped)
48
Q

Lysogenic infection is also known as…

A

latent infection

49
Q

With a lysogenic infection, what happens to the viral genome?

A

Viral genome becomes incorporated into host cell’s DNA, remaining for a long period of time

50
Q

Give three examples of lysogenic/latent infections

A
  • HIV
  • Hepatitis B and C
  • HPV
51
Q

Describe the number of virions over the course of an acute infection

A

Initial number of virions drops for a short eclipse period followed by a longer spike of virions being released from the host cell that peaks and declines

52
Q

How long will an acute viral infection last?

A

A matter of days

53
Q

Describe the number of virions over the course of a persistent infection

A

Gradual increase in virions followed by a spike

54
Q

Describe the number of virions over the course of a latent infection

A

Sudden spike in virions with a later onset than acute infection

55
Q

How long will a persistent infection last?

A

Months to years

56
Q

How long might it take to see a spike in virions from a latent infection?

A

Months to years

57
Q

What is antigenic shift?

A

Process of viral antigenic variation caused by the reassortment of genes

58
Q

Shuffling of the viral genome in antigenic shift leads to…

A

major changes in viral proteins

59
Q

How does the host immune system react to viral proteins changed by antigenic shift?

A

Host immune system does not recognize the changed proteins

60
Q

What is antigenic drift?

A

Process of viral antigenic variation that results from mutations

61
Q

Can cytotoxic T cells recognize epitopes from antigenic drift?

A

No

62
Q

What is the process of viral antigenic variation caused by the reassortment of genes?

A

Antigenic shift

63
Q

What is the process of viral antigenic variation that results from mutations?

A

Antigenic drift

64
Q

What are three types of vaccines for viruses?

A
  • Live attenuated
  • Inactivated (killed)
  • Sub-unit
65
Q

What are the contents of live attenuated vaccines?

A

Intact viral particles that have been mutated and selected for poor infectivity

66
Q

What type of vaccine is used for MMR (measles, mumps, rubella) and oral poliovirus (OPV)?

A

Live attenuated

67
Q

What are the contents of inactivated vaccines?

A

“Dead” or non-infectious virus via chemical or physical treatment

68
Q

What type of vaccine is used for poliovirus?

A

Inactivated

69
Q

What are the contents of sub-unit vaccines?

A

Immunogenic parts of the virus via genetic engineering and recombinant DNA technology

70
Q

What type of vaccine is used for Hepatitis B?

A

Sub-unit

71
Q

What is a prion?
How do they relate to propagation of a disease?

A

A misfolded protein; the active component of the infectious agent
Propagation of a disease and its features depend on self-replication of prions

Clinical Microbiology (6 decks)

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