CH 7 VIRUSES Flashcards

1
Q

About how small are viruses?

A

0.02-0.3 mcg

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2
Q

Why are viruses different from living cells?

A

Cannot metabolize or reproduce independently

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3
Q

How are viruses classified?

A

By morphology and type of genetic material

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4
Q

Name two classification systems for viruses

A
  1. International committee for taxonomy of viruses
  2. Baltimore classification system
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5
Q

Name 2 general components of the viral covering

A
  1. Capsid
  2. Envelope
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6
Q

Name 2 general components of the viral core

A
  1. Nucleic acid
  2. Enzymes
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7
Q

What may surround the viral genome?

A

Nucleocapsid

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8
Q

What viral action causes tissue damage?

A

Reproduction

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9
Q

Viral capsule proteins that specialize in binding certain cell receptors determine the virus’s what?

A

Viral tropism

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10
Q

What are three mechanisms viruses use to enter through the cell membrane?

A
  1. Endocytosis
  2. Fusion
  3. Adherence and translocation
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11
Q

What is the cycle through which the viral genome is inserted into the host genome?

A

Lysogenic cycle

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12
Q

What is the cycle through which the virus directs the cell to produce new viral capsid proteins?

A

Lytic cycle

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13
Q

What are two ways viruses may exit the cell?

A
  1. Transport through vesicles
  2. Directly emerging through cell membrane
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14
Q

What are two reasons why some animal viruses are able to infect humans?

A
  1. Compatible viral receptor proteins
  2. Mutations of same
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15
Q

What are some cytopathic effects of viruses?

A
  1. Changes in morphology
  2. Abnormal fusion
  3. Gene mutation leading to atrophy, hyperplasia, or dysplasia
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16
Q

What advantage do enveloped viruses have?

A

A patch of the host cell’s membrane stay with the virus as it buds off, which helps it to integrate into the next cell.

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17
Q

Name 3 types of enveloped DNA viruses

A
  1. Poxviruses
  2. Herpesviruses
  3. Hepadnaviruses
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18
Q

Which enveloped DNA virus causes smallpox?

A

Variola virus

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19
Q

How is variola virus transmitted?

A

Contact

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20
Q

What tissue does variola virus target, and where does it multiply?

A

Respiratory tract, lymph nodes

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21
Q

Name 8 types of herpesviruses

A
  1. Herpes simplex 1
  2. Herpes simplex 2
  3. Varicella zoster
  4. Cytomegalovirus
  5. Epstein-Barr
  6. Human herpes 6
  7. Human herpes 7
  8. Human herpes 8
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22
Q

How are herpesviruses transmitted?

A

Contact and respiratory aerosol

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23
Q

After initial manifestation of a painful vesicle, where do herpesviruses go to enter latency?

A

Dosal root ganglia

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24
Q

Which enveloped DNA virus causes cold sores and oral herpes?

A

HSV1

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25
Q

Which enveloped DNA virus causes genital herpes?

A

HSV2

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26
Q

How are herpes simplex viruses activated?

A

Stress causes corticosteroid induced activation of JNK protein

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27
Q

Which enveloped DNA virus causes chickenpox and shingles?

A

Varicella zoster virus

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28
Q

Which tissues are the target of VZV?

A

Respiratory mucosa, skin

29
Q

Which enveloped DNA virus mostly presents as an opportunistic infection?

A

Cytomegalovirus

30
Q

How is CMV transmitted?

A

Body fluids

31
Q

Which enveloped DNA virus causes mononucleosis, Burkitt’s lymphoma, and Hodgkin’s lymphoma?

A

Epstein-Barr virus

32
Q

How is EBV transmitted?

A

Body fluids, especially saliva

33
Q

Which enveloped DNA virus targets hepatocytes?

A

Hepatitis B virus

34
Q

Which nonenveloped DNA viruses cause distinctive pharyngoconjunctival fever, bronchiolitis, pneumonia, and acute hemorrhagic cystitis?

A

Adenoviruses

35
Q

Which nonenveloped DNA viruses cause cervical cancer?

A

HPV 16 and 18

36
Q

Which group of viruses cause influenza?

A

Orthomyxoviruses

37
Q

What two things make up the glycoprotein spikes unique to influenza viruses?

A

Hemagglutinin and neuraminidase

38
Q

Which term describes the accumulation of mutations of influenza surface proteins?

A

Antigenic drift

39
Q

Which term describes the way viruses exchange genetic material to create hybrids?

A

Antigenic shift

40
Q

Name 3 types of paramyxoviruses

A
  1. Morbillovirus
  2. Mumps virus
  3. Respiratory syncytial virus
41
Q

Which RNA paramyxovirus causes measles?

A

Morbillovirus

42
Q

What can mumps virus infection lead to?

A

Epidemic parotiditis

43
Q

What is another term for the RNA paramyxovirus respiratory syncytial virus?

A

Pneumovirus

44
Q

Rabies virus belongs to which group of RNA viruses?

A

Rhabdoviruses

45
Q

Which group of RNA viruses includes poliovirus and Hepatitis A?

A

Picornaviruses

46
Q

Which RNA picornavirus causes poliomyelitis?

A

Poliovirus

47
Q

How are polio and Hepatitis A spread?

A

Fecal-oral

48
Q

Which cells are targeted by HIV?

A

Helper T cells, macrophages, microglia, dendritic cells

49
Q

Which cells are targeted by EBV?

A

B cells

50
Q

What is the term for proteinaceous particles that cause transmissable spongiform encephalopathy?

A

Prions

51
Q

Name an example of transmissable spongiform encephalopathy

A

Cruetzfeldt-Jakob disease

52
Q

Name two viral categories based on the appearance of their genetic material

A

Helical and isocahedral

53
Q

Name 3 ways viral culturing is done

A
  1. Inoculate live animals
  2. Inoculate bird embryos
  3. Use cell culture
54
Q

How are chronic viral infections different from latent viral infections?

A

Chronic: virus multiplies slowly, symptoms mild or absent
Latent: after lytic cycle, become undetectable. Can reactivate

55
Q

What is the term for a virus that can cross the placental barrier?

A

Teratogenic

56
Q

Which enveloped DNA viruses cause exanthema subitum and lymphoproliferative diseases?

A

Human herpes viruses 6, 7

57
Q

Which enveloped DNA virus causes Kaposi sarcoma?

A

Human herpes virus 8

58
Q

How are the Hep A, B, and C viruses different?

A
  1. Hep A is an enveloped RNA picornavirus
  2. Hep B is an enveloped DNA hepadnavirus
  3. Hep C is an enveloped DNA flavivirus
59
Q

What conditions can human herpes 6 and 7 lead to?

A

Exanthema subitum, lymphoproliferative diseases

60
Q

What disease is associated with human herpes 8?

A

Kaposi sarcoma

61
Q

Why are polyoma viruses and parvoviruses unique?

A

Generally only affect animals

62
Q

How are orthomyxoviruses different from other enveloped RNA viruses?

A

Segmented genome

63
Q

What group of viruses does rubella belong to?

A

Togaviruses

64
Q

What group of viruses does dengue virus and Hepatitis C belong to?

A

Flaviviruses

65
Q

What group of viruses does Ebola virus belong to?

A

Filoviruses

66
Q

Why are paramyxoviruses, rhabdoviruses, coronaviruses, togaviruses, flaviviruses, and filoviruses unique?

A

RNA, enveloped, single stranded, non-segmented

67
Q

Why are picornaviruses and reoviruses different from other RNA viruses?

A

Non-enveloped genome

68
Q

How do picornaviruses differ from reoviruses?

A

Single stranded genome

69
Q

What is an example of reoviruses?

A

Rotavirus