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UVic BIOL 459 - Fall 2019 > Final > Infectious Agents: Viruses > Flashcards

Final > Infectious Agents: Viruses Flashcards

1
Q

What are the 5 main features of viruses that differentiate them from bacteria?

A
  1. Obligatory intracellular parasites
  2. Contain DNA or RNA
  3. Contain a protein coat
  4. No ribosomes
  5. No ATP-generating mechanism
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2
Q

What main replicative feature (used to differentiate bacteria) do viruses lack?

A

16S rRNA.

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3
Q

Which bacteria share certain features with viruses but not other bacteria? What are these features?

A

Rickettsias and Chlamydias are both intracellular parasites and sometimes require a host for ATP generation.

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4
Q

What is meant by the term “Host Range” with regards to viruses?

A

The spectrum of host cells a virus can infect.

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5
Q

What 2 main factors determine the host range of a virus?

A
  1. Specific host attachment sites

2. Protein-protein interaction

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6
Q

What is the the size range of a bacteriophage?

A

20nm to 1000nm in length.

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7
Q

Are bacteriophages specific to a certain type of bacteria?

A

Yes.

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8
Q

What 4 components compose a virion (fully developed viral particle)?

A
  1. Nucleic acid
  2. Capsid
  3. Envelope
  4. Spikes
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9
Q

Do all viruses have an envelope? Does influenza virus?

A

No, some don’t. Influenza does though (N protein).

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10
Q

What is the name of the subunits which make up the viral capsid?

A

Capsomeres.

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11
Q

What does a complex virus look like?

A

Its the one with the spider legs and polyhedral head. Iconic.

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12
Q

Viral genus names end in ________.

A

-virus.

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13
Q

Viral family names end in ________.

A

-viridae.

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14
Q

Viral order names end in ________.

A

-ales.

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15
Q

What is the definition of viral species?

A

A group of viruses sharing the same genetic information and ecological niche (host).

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16
Q

Regarding a viral life cycle, what does the size of the virus indicate?

A

A more complex life cycle.

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17
Q

How are bacteriophages grown in the laboratory? How can they be recognized?

A

In agar cultures of bacteria. Plaques (clear areas) form around bacteriophages on the agar surface.

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18
Q

What unit can be used to quantify the presence of bacteriophages in an agar culture?

A

Plaque-forming units (PFU).

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19
Q

Approximately what percentage of human infections are caused by viruses?

A

~20%.

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20
Q

What must a virus also have it it carries its genetic material as RNA?

A

Reverse transcriptase.

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21
Q

What must a virus also have if it carries its genetic material as DNA?

A

Regular ol’ transcriptase (polymerase).

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22
Q

Where in a bacterial cell does viral infection occur? What about in eukaryotic cells?

A

Bacteria: cytosol
Eukaryotes: cytosol or nucleus

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23
Q

Describe the eclipse period of a viral infection.

A

The period while the virus is replicating in the cell and before mature virions are released.

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24
Q

Describe the acute period of viral infection.

A

When virion release from the cell ramps up and before the immune response takes over.

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25
Q

What is the difference between the viral lytic cycle and a viral lysogenic cycle?

A

Lytic: phage causes lysis of cell upon replication
Lysogenic: phage DNA incorporated into host DNA and replicates normally

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26
Q

What 5 main steps outline the viral lytic cycle?

A
  1. Attachment
  2. Penetration
  3. Biosynthesis
  4. Maturation
  5. Release (lysis)
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27
Q

What term is used to describe the inserted phage DNA before it becomes a new virion?

A

A prophage. duh.

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28
Q

What is meant by “specialized transduction” with regards to bacterial/viral reproduction?

A

When a bacteria takes advantage of a phage to spread its genes to other bacteria for reproduction.

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29
Q

With 2 exceptions, RNA viruses reproduce in the cytosol and DNA viruses reproduce in the nucleus. What are these exception?

A
  1. Influenza virus is RNA but reproduces in the nucleus

2. Smallpox is DNA but reproduces in the cytosol

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30
Q

How are enveloped viruses released from the cell? What about non-enveloped viruses?

A

Enveloped: budding (endocytosis)

Non-enveloped: lysis

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31
Q

What kind of genome do class I viruses have? What are some examples of viruses in this category?

A

dsDNA. Ex: Smallpox, Herpes, HPV, Varicella, Epstein-Barr.

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32
Q

What kind of genome do class II viruses have? What are some examples of viruses in this category?

A

ssDNA. Ex: Parvovirus (non-pathogenic).

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33
Q

What kind of genome do class III viruses have? What are some examples of viruses in this category?

A

dsRNA. Ex: Rotavirus (non-notifiable) (but Rotavec is a vaccine on the schedule in BC!).

34
Q

What kind of genome do class IV viruses have? What are some examples of viruses in this category?

A

ssRNA (+). Ex: Polio, WNV, Zika, Dengue, Hep A & C, Rubella, Yellow fever, Norovirus.

35
Q

What kind of genome do class V viruses have? What are some examples of viruses in this category?

A

ssRNA (-). Ex: Measles, Mumps, Influenza, Rabies, Hantavirus, Ebola, Marburg.

36
Q

What kind of genome do class VI viruses have? What are some examples of viruses in this category?

A

ssRNA with DNA stage. Ex: HIV, retroviruses in general.

37
Q

What kind of genome do class VII viruses have? What are some examples of viruses in this category?

A

Partial dsDNA. Ex: Hep B (has an RNA stage, uses reverse transcriptase).

38
Q

When was the first retrovirus discovered? By who?

A

David Baltimore and Howard Timmins discovered the first retrovirus in 1970.

39
Q

Where in the host cell is the viral capsid synthesized?

A

In the cytoplasm.

40
Q

What 2 notifiable diseases belong to class I (dsDNA viruses)?

A
  1. Smallpox (poxviridae)

2. Chickenpox (herpesviridae)

41
Q

What does adenoviridae infection cause in humans? What about animals?

A

Adenoviridae causes respiratory infections in humans and tumours in animals.

42
Q

What are some examples of poxviridae viruses? What does poxviridae infection cause in humans?

A

Smallpox, vaccinia, cowpox, monkeypox, camelpox. Causes skin lesions.

43
Q

What is the origin of vaccinia (a type of poxviridae)?

A

No one knows for sure!

44
Q

Why is it important for the variola virus genome to have inverted tandem repeats at both ends? How are these sometimes activated?

A

To enable circularization/insertion. Sometimes triggered by UV light exposure.

45
Q

List as many examples of Herpesviridae viruses as you can (HHV-1 to HHV-8).

A 
HHV-1 Simplexvirus
HHV-2 Simplexvirus
HHV-3 Varicellovirus
HHV-4 Epstein-Barr virus
HHV-5 Cytomegalovirus
HHV-6 Roseolovirus
HHV-7 Roseolovirus
HHV-8 Rhadinovirus
46
Q

What is Kaposi’s sarcoma?

A

A cancer of the connective tissue which presents as reddish purple colour under the skin.

47
Q

What is an example of a papovaviridae? What does this cause in humans?

A

Papillomavirus. Can cause warts and transform cells to cause cancer (esp. in women).

48
Q

How can HPV be implicated in cancer development?

A

Because one of its early genes binds to p53, a well known oncogene.

49
Q

What virus covered in class was the only example of a ssDNA virus

A

Parvovirus B19 (non-pathogenic).

50
Q

What virus covered in class was the only example of a partial dsDNA virus? What can infection by this virus cause?

A

Hepatitis B virus. Can cause jaundice.

51
Q

What differentiates ssRNA (+) from ssRNA (-)?

A

(+): sense, RNA acts as mRNa and is translated directly.

(-): antisense, transcribed to + strand before translation.

52
Q

What virus covered in class was the only example of a dsRNA virus? What can infection by this virus cause?

A

Rotavirus. Non-notifiable but can cause infant diarrhea and mild respiratory infection.

53
Q

What is a picornavirus?

A

A large family of small, non-enveloped, cytoplasmic, ssRNA (+) viruses with a capsid. No lipid membrane.

54
Q

What is the most well known example of an enterovirus (in the family picornaviridae)?

A

Poliovirus.

55
Q

What is the most well known example of a rhinovirus (in the family picornaviridae)?

A

Rhinovirus (common cold).

56
Q

Besides the rhinoviruses and the enteroviruses, what other prominent virus belongs to the picornaviridae family?

A

Hepatitis A virus.

57
Q

What are togaviridae?

A

A family of enveloped ssRNA (+) viruses with a capsid. (pretty much identical to flaviviridae, but a little bigger)

58
Q

What differentiates picornaviridae from togaviridae?

A

Picornaviridae: non-enveloped
Togaviridae: enveloped

59
Q

Into what 2 genera is the togaviridae family divided?

A
  1. Alphavirus

2. Rubivirus

60
Q

What 3 viruses are countered by the MMR vaccine given to children? What genotype does it target?

A
  1. Measles
  2. Mumps
  3. Rubella
    Target A genotype, though effective against some others.
61
Q

What are flaviviridae?

A

A family of enveloped ssRNA (+) viruses with a capsid. (pretty much identical to togaviridae, but a little smaller)

62
Q

What are 3 examples of viruses belonging to the flaviviridae family (ssRNA (+))?

A
  1. Hepatitis C
  2. West Nile virus
  3. Yellow fever virus
    * Both WNV and YFV are transmitted by arthropods. Neat!
63
Q

How is hepatitis C transmitted?

A

By blood, sex, pregnant mother to infant, needles, etc.

64
Q

What virus in the norovirus genus is notifiable, can cause gastroenteritis, and is most common in winter?

A

Norwalk virus.

65
Q

What are rhabdoviridae?

A

A family of bullet-shaped, enveloped ssRNA (-) viruses with a capsid. Must first transcribe mRNA before replication.

66
Q

What is the only example of a virus in the rhabdoviridae family that was shown in class?

67
Q

What are the 2 examples of paramyxoviridae that were presented in lecture? What class do they belong to?

A
  1. Measles (morbillivirus)
  2. Mumps (rubulavirus)
    Both are class V ssRNA (-).
68
Q

What class does hantavirus (family: hantaviridae) belong to? How would this best be treated?

A

Class V ssRNA (-). Treat with drugs which target polymerase and inhibit synthesis.

69
Q

What makes the structure of the filoviridae virus family so unique? What is an example of a virus in this family?

A

A long, enveloped helical virus that’s more like a spaghetti than a d20. Ex: Marburg virus, Ebola virus.

70
Q

In Canada, what is the only notifiable disease from the retroviridae virus family? What class does this belong to?

A

HIV/AIDS. Class VI ssRNA with a DNA stage.

71
Q

What do class VI viruses require for replication that class IV viruses do not? Why?

A

Reverse transcriptase to produce DNA from the viral ssRNA genome for integration into the host chromosome.

72
Q

What is another way to say “reverse transcriptase”?

A

RNA-dependent DNA polymerase.

73
Q

What is HAART? How does it work?

A

Highly Active AntiRetroviral Therapy (for HIV). Prevents replication and limits viral load.

74
Q

What is a sarcoma?

A

A cancer of the connective tissue.

75
Q

What is an adenocarcinoma?

A

A cancer of glandular epithelial tissue.

76
Q

What is an oncogenic virus?

A

A virus which integrates with the host cell’s DNA and induces tumours.

77
Q

What are some examples of DNA oncogenic viruses?

A
  • Hepatitis B
  • Hepatitis C
  • Human Papillomavirus (HPV)
  • Smallpox (+other pox)
  • Epstein-Barr
  • Any retroviruses!
78
Q

What is a latent virus? What are some examples?

A

A virus which remains asymptomatic in host cells for long periods. Ex: Herpes, Leukemia, Shingles

79
Q

What is a persistent viral infection? What are some examples of viruses which can cause these?

A

Infection over a long period, usually fatal. Ex: Measles, Rubella, HIV, HPV, Hepatitis B

80
Q

What is Epstein-Barr virus also known as? What condition is it the leading cause of?

A

Also known as human herpes virus 4. Known to be a primary cause of infectious mononucleosis (mono).

UVic BIOL 459 - Fall 2019 (16 decks)

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