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MICRB 106 - FINAL > Pathogenic RNA Viruses > Flashcards

Pathogenic RNA Viruses Flashcards

1
Q

What is the morphology of retroviruses?

A

Polyhedral capsids

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2
Q

Retroviruses have ______ envelopes

A

Spiked

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3
Q

What other kinds of enzymes are present in the virion of HIV other than the genome, capsid and envelope? (3)

A
  • Reverse transcriptase
  • Integrase
  • Protease
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4
Q

How do retroviruses violate the central dogma of molecular genetics?

A

They transcribe DNA from RNA

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5
Q

Describe the 4 step mechanism of reverse transcriptase

A
  • tRNA is used as a primer
  • RNA is degraded
  • -ssDNA transcribes +ssDNA
  • Forms dsDNA
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6
Q

Why is AIDS considered a ‘syndrome’?

A

It is a complex of signs, symptoms, and diseases

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7
Q

What is the causative agent of AIDS?

A

HIV

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8
Q

What is the primary target cell of HIV?

A

Helper T cells

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9
Q

In which countries is HIV-1 most prevalent? (2)

A
  • US
  • Europe
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10
Q

What is the alternative name for helper T cells?

A

CD4 cells

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11
Q

In which country is HIV-2 most prevalent?

A

West Africa

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12
Q

What are glycoproteins?

A

The envelope of HIV

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13
Q

Which HIV glycoprotein is known as the primary attachment molecule?

A

gp120

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14
Q

Describe the significance of antigenic changes associated with HIV gp120

A

They make it difficult for the body to make an antibody response

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15
Q

What is the function of gp41 in the life cycle of HIV?

A

Fusion of the viral envelope with the endosome membrane

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16
Q

What is the origin of HIV?

A

A mutation of SIV

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17
Q

When did HIV first emerge in the human population?

A

1920

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18
Q

When was the first case of AIDS documented?

A

1981

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19
Q

How does HIV enter a host cell?

A

Endocytosis

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20
Q

When does uncoating of the HIV nucleocapsid commence?

A

After the capsid enters the cytosol

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21
Q

What is the template of HIV reverse transcriptase?

A

ssRNA

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22
Q

What is the product of HIV reverse transcriptase?

A

dsDNA

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23
Q

Explain how HIV creates a latent infection

A

It integrates into the human chromosome

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24
Q

Where are HIV genes transcribed?

A

In the nucleus

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25
Q

Ribosomes translate mRNA to make ______

A

Polypeptides

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26
Q

What are the 3 different types of macromolecules that are released from the host’s cytoplasmic membrane to form an immature virion?

A
  • tRNA
  • mRNA
  • Polypeptides
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27
Q

Why is HIV nonvirulent after immediately budding from a cell? (2)

A
  • Reverse transcriptase is inactive
  • Capsids are not functional
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28
Q

What does HIV protease cleave in the final assembly of HIV after budding from the cell membrane?

A

Polypeptides

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29
Q

What is released as a result of cleaved polypeptides from HIV protease? (2)

A
  • Reverse transcriptase
  • Capsomeres
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30
Q

What is the receptor for HIV gp120 on the target cell’s cytoplasmic membrane?

A

CD4

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31
Q

How does the CD4-gp120 receptor complex attach to the cytoplasmic membrane?

A

Membrane fusion

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32
Q

What is the function of the fusin receptor on the target cell’s cytoplasmic membrane during attachment / entry of HIV?

A

Triggers endocytosis

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33
Q

What is the name of the vesicle that HIV exists in after being endocytosed?

A

Endosome vesicle

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34
Q

The viral nucleocapsid is released into the ______

A

Cytosol

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35
Q

What is the significance of HIV reverse transcriptase being error prone?

A

It generates multiple antigenic variations of HIV

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36
Q

Where does the provirus state of HIV exist?

A

The nucleus

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37
Q

What is the function of HIV integrase?

A

Inserts the dsDNA provirus into a human chromosome

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38
Q

Is the provirus state of HIV a temporary or permanent condition?

A

Permanent

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39
Q

What are protease inhibitors?

A

Drugs that interfere with the function of HIV protease

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40
Q

Protease inhibitors are a ______

A

Standard therapeutic agent

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41
Q

What kinds of diseases do most AIDS patients suffer from? (2)

A
  • Disseminated herpes
  • Kaposi’s sarcoma
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42
Q

How are diseases in HIV-infected people different from non-HIV-infected people?

A

They would usually be nonlethal, but AIDS patients cannot effectively resist them

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43
Q

Where and in what population was AIDS first identified?

A

Young male homosexuals

44
Q

What kinds of body secretions of AIDS patients contain HIV?

A

ALL

45
Q

What are considered the most infectious bodily fluids associated with HIV transmission? (4)

A
  • Blood
  • Semen
  • Vaginal secretions
  • Breast milk
46
Q

What are the 2 main routes by which HIV is transmitted?

A
  • Sexual contact
  • Intravenous drug use
47
Q

How is HIV infection diagnosed?

A

Enzyme-linked immunosorbent assay testing (ELISA)

48
Q

How is ELISA used to diagnose HIV infection?

A

Detection of antibodies against HIV

49
Q

What drugs are included in antiretroviral therapy (ART) in the treatment of AIDS? (4)

A
  • Nucleotide analogs
  • Reverse transcriptase inhibitors
  • Integrase inhibitors
  • Protease inhibitors
50
Q

How many people died during the flu pandemic of 1918 - 1919?

A

40 million

51
Q

What is the causative agent of influenza?

A

Orthomyxoviruses A / B

52
Q

A ______ genome contains 8 different -ssRNA molecules

A

Segmented

53
Q

What is the function of influenza hemagglutinin (HA) glycoprotein spikes?

A

Trigger endocytosis

54
Q

What is the function of influenza neuraminidase (NA) glycoprotein spikes?

A

Hydrolyze mucus

55
Q

How are influenza viruses transmitted?

A

Respiratory droplets

56
Q

How do influenza viruses enter epithelial cells?

A

Endocytosis

57
Q

Why does the flu increase susceptibility to bacterial infections?

A

Death of epithelial cells reduces the first line of defense of the lungs

58
Q

How long is the incubation period for influenza?

A

1 day

59
Q

What is the distinguishing sign of flu?

A

Fever

60
Q

Antigenic drift is a ______ change

A

Slow, gradual

61
Q

______ causes mutations within a single strain of virus

A

Antigenic drift

62
Q

Antigenic shift is a ______ change

A

Major

63
Q

______ causes reassortment of genes from different influenza A viruses infecting the same host cell

A

Antigenic shift

64
Q

______ has a greater antigenic variability

A

Antigenic shift

65
Q

Antigenic shift can result in ______

A

Major epidemics

66
Q

What type of vaccines are used to prevent the flu?

A

Multivalent vaccines

67
Q

Rhinoviruses cause ______

A

Most colds

68
Q

What body system do rhinoviruses infect?

A

Upper respiratory tract

69
Q

What is the significance of rhinoviruses replicating best at a temperature of 33°C?

A

It is the temperature of the nasal cavity

70
Q

How are rhinoviruses transmitted? (3)

A
  • Aerosoles
  • Direct contact
  • Fomites
71
Q

Why is an effective vaccine for the common cold impractical?

A

It would have to immunize against hundreds of strains

72
Q

What is the most important preventative measure to avoid contracting the common cold?

A

Antisepsis

73
Q

Do enteroviruses normally cause diseases of the digestive system?

A

NO

74
Q

Why are enteroviruses named enteroviruses?

A

They are transmitted via the fecal-oral route

75
Q

What body systems do enteroviruses infect? (2)

A
  • Pharynx
  • Intestine
76
Q

How do enteroviruses spread throughout the body?

A

Through the blood

77
Q

The presence of viruses in the blood referes to ______

A

Viremia

78
Q

Explain why enteroviruses are described as being ‘cytolytic’

A

They kill their host cells

79
Q

Describe the pathology of paralytic polio

A

Viruses invade the spinal cord and motor cortex - causing paralysis

80
Q

Paralytic polio is relatively ______

A

Rare

81
Q

What is post polio syndrome?

A

Deterioration of polio-affected muscles after the original infection

82
Q

Which polio vaccine is an inactivated vaccine?

A

Salk

83
Q

Which polio vaccine is a live attenuated oral vaccine?

A

Sabin

84
Q

Describe the risk associated with the Sabin polio vaccine

A

Occasionally mutates into a virulent form

85
Q

______ is caused by caliciviruses and astroviruses

A

Acute gastroenteritis

86
Q

What are the best studies of the caliciviruses?

A

Noroviruses

87
Q

Why are noroviruses / ‘norwalk’ viruses named such?

A

They were first discovered during the epidemic of diarrhea in Norwalk, Ohio

88
Q

What percentage of viral gastroenteritis are caused by noroviruses?

A

90%

89
Q

What is the standard treatment for caliciviral / astroviral gastroenteritis?

A

Fluid and electrolyte replacement

90
Q

What family does the rubella virus belong to?

A

Togaviruses

91
Q

How is transmission of the rubella virus different from other togaviruses?

A

Respiratory droplets - NOT arthropod vectors

92
Q

Why is the disease rubella also called ‘German measles’?

A

It was first distinguished by German physicians

93
Q

What body system is the site of entering rubella viruses?

A

Upper respiratory tract

94
Q

How does the rubella virus spread throughout the body?

A

Through the blood

95
Q

Describe the characteristic rash of rubella

A

Macules

96
Q

Is rubella more serious for children or adults?

A

Adults

97
Q

Describe the complications associated with rubella infection in pregnant women

A

Severe congenital defects

98
Q

How is rubella prevented – what type of vaccine?

A

Live attenuated vaccine

99
Q

What types of patients should NOT receive the rubella vaccine? (2)

A
  • Pregnant women
  • Immunocompromised patients
100
Q

What family does the hepatitis C virus belong to?

A

Flaviviruses

101
Q

Is hepatitis C a chronic or an acute disease?

A

Chronic

102
Q

Hepatitis C is a ______ virus

A

Bloodborne

103
Q

Is hepatic cancer a possible complication of hepatitis C?

A

YES

104
Q

What is the function of antivirals in treating hepatitis C?

A

Reduce the number of viruses

105
Q

Is there a vaccine for hepatitis C?

A

NO

MICRB 106 - FINAL (4 decks)

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