Pathogenic RNA Viruses Flashcards
1
Q
What is the morphology of retroviruses?
A
Polyhedral capsids
2
Q
Retroviruses have ______ envelopes
A
Spiked
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
4
Q
How do retroviruses violate the central dogma of molecular genetics?
A
They transcribe DNA from RNA
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
6
Q
Why is AIDS considered a ‘syndrome’?
A
It is a complex of signs, symptoms, and diseases
7
Q
What is the causative agent of AIDS?
A
HIV
8
Q
What is the primary target cell of HIV?
A
Helper T cells
9
Q
In which countries is HIV-1 most prevalent? (2)
A
- US
- Europe
10
Q
What is the alternative name for helper T cells?
A
CD4 cells
11
Q
In which country is HIV-2 most prevalent?
A
West Africa
12
Q
What are glycoproteins?
A
The envelope of HIV
13
Q
Which HIV glycoprotein is known as the primary attachment molecule?
A
gp120
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
15
Q
What is the function of gp41 in the life cycle of HIV?
A
Fusion of the viral envelope with the endosome membrane
16
Q
What is the origin of HIV?
A
A mutation of SIV
17
Q
When did HIV first emerge in the human population?
A
1920
18
Q
When was the first case of AIDS documented?
A
1981
19
Q
How does HIV enter a host cell?
A
Endocytosis
20
Q
When does uncoating of the HIV nucleocapsid commence?
A
After the capsid enters the cytosol
21
Q
What is the template of HIV reverse transcriptase?
A
ssRNA
22
Q
What is the product of HIV reverse transcriptase?
A
dsDNA
23
Q
Explain how HIV creates a latent infection
A
It integrates into the human chromosome
24
Q
Where are HIV genes transcribed?
A
In the nucleus
25
Ribosomes translate mRNA to make ______
Polypeptides
26
What are the 3 different types of macromolecules that are released from the host’s cytoplasmic membrane to form an immature virion?
- tRNA
- mRNA
- Polypeptides
27
Why is HIV nonvirulent after immediately budding from a cell? (2)
- Reverse transcriptase is inactive
- Capsids are not functional
28
What does HIV protease cleave in the final assembly of HIV after budding from the cell membrane?
Polypeptides
29
What is released as a result of cleaved polypeptides from HIV protease? (2)
- Reverse transcriptase
- Capsomeres
30
What is the receptor for HIV gp120 on the target cell’s cytoplasmic membrane?
CD4
31
How does the CD4-gp120 receptor complex attach to the cytoplasmic membrane?
Membrane fusion
32
What is the function of the fusin receptor on the target cell’s cytoplasmic membrane during attachment / entry of HIV?
Triggers endocytosis
33
What is the name of the vesicle that HIV exists in after being endocytosed?
Endosome vesicle
34
The viral nucleocapsid is released into the ______
Cytosol
35
What is the significance of HIV reverse transcriptase being error prone?
It generates multiple antigenic variations of HIV
36
Where does the provirus state of HIV exist?
The nucleus
37
What is the function of HIV integrase?
Inserts the dsDNA provirus into a human chromosome
38
Is the provirus state of HIV a temporary or permanent condition?
Permanent
39
What are protease inhibitors?
Drugs that interfere with the function of HIV protease
40
Protease inhibitors are a ______
Standard therapeutic agent
41
What kinds of diseases do most AIDS patients suffer from? (2)
- Disseminated herpes
- Kaposi’s sarcoma
42
How are diseases in HIV-infected people different from non-HIV-infected people?
They would usually be nonlethal, but AIDS patients cannot effectively resist them
43
Where and in what population was AIDS first identified?
Young male homosexuals
44
What kinds of body secretions of AIDS patients contain HIV?
ALL
45
What are considered the most infectious bodily fluids associated with HIV transmission? (4)
- Blood
- Semen
- Vaginal secretions
- Breast milk
46
What are the 2 main routes by which HIV is transmitted?
- Sexual contact
- Intravenous drug use
47
How is HIV infection diagnosed?
Enzyme-linked immunosorbent assay testing (ELISA)
48
How is ELISA used to diagnose HIV infection?
Detection of antibodies against HIV
49
What drugs are included in antiretroviral therapy (ART) in the treatment of AIDS? (4)
- Nucleotide analogs
- Reverse transcriptase inhibitors
- Integrase inhibitors
- Protease inhibitors
50
How many people died during the flu pandemic of 1918 - 1919?
40 million
51
What is the causative agent of influenza?
Orthomyxoviruses A / B
52
A ______ genome contains 8 different -ssRNA molecules
Segmented
53
What is the function of influenza hemagglutinin (HA) glycoprotein spikes?
Trigger endocytosis
54
What is the function of influenza neuraminidase (NA) glycoprotein spikes?
Hydrolyze mucus
55
How are influenza viruses transmitted?
Respiratory droplets
56
How do influenza viruses enter epithelial cells?
Endocytosis
57
Why does the flu increase susceptibility to bacterial infections?
Death of epithelial cells reduces the first line of defense of the lungs
58
How long is the incubation period for influenza?
1 day
59
What is the distinguishing sign of flu?
Fever
60
Antigenic drift is a ______ change
Slow, gradual
61
______ causes mutations within a single strain of virus
Antigenic drift
62
Antigenic shift is a ______ change
Major
63
______ causes reassortment of genes from different influenza A viruses infecting the same host cell
Antigenic shift
64
______ has a greater antigenic variability
Antigenic shift
65
Antigenic shift can result in ______
Major epidemics
66
What type of vaccines are used to prevent the flu?
Multivalent vaccines
67
Rhinoviruses cause ______
Most colds
68
What body system do rhinoviruses infect?
Upper respiratory tract
69
What is the significance of rhinoviruses replicating best at a temperature of 33°C?
It is the temperature of the nasal cavity
70
How are rhinoviruses transmitted? (3)
- Aerosoles
- Direct contact
- Fomites
71
Why is an effective vaccine for the common cold impractical?
It would have to immunize against hundreds of strains
72
What is the most important preventative measure to avoid contracting the common cold?
Antisepsis
73
Do enteroviruses normally cause diseases of the digestive system?
NO
74
Why are enteroviruses named enteroviruses?
They are transmitted via the fecal-oral route
75
What body systems do enteroviruses infect? (2)
- Pharynx
- Intestine
76
How do enteroviruses spread throughout the body?
Through the blood
77
The presence of viruses in the blood referes to ______
Viremia
78
Explain why enteroviruses are described as being ‘cytolytic’
They kill their host cells
79
Describe the pathology of paralytic polio
Viruses invade the spinal cord and motor cortex - causing paralysis
80
Paralytic polio is relatively ______
Rare
81
What is post polio syndrome?
Deterioration of polio-affected muscles after the original infection
82
Which polio vaccine is an inactivated vaccine?
Salk
83
Which polio vaccine is a live attenuated oral vaccine?
Sabin
84
Describe the risk associated with the Sabin polio vaccine
Occasionally mutates into a virulent form
85
______ is caused by caliciviruses and astroviruses
Acute gastroenteritis
86
What are the best studies of the caliciviruses?
Noroviruses
87
Why are noroviruses / ‘norwalk’ viruses named such?
They were first discovered during the epidemic of diarrhea in Norwalk, Ohio
88
What percentage of viral gastroenteritis are caused by noroviruses?
90%
89
What is the standard treatment for caliciviral / astroviral gastroenteritis?
Fluid and electrolyte replacement
90
What family does the rubella virus belong to?
Togaviruses
91
How is transmission of the rubella virus different from other togaviruses?
Respiratory droplets - NOT arthropod vectors
92
Why is the disease rubella also called ‘German measles’?
It was first distinguished by German physicians
93
What body system is the site of entering rubella viruses?
Upper respiratory tract
94
How does the rubella virus spread throughout the body?
Through the blood
95
Describe the characteristic rash of rubella
Macules
96
Is rubella more serious for children or adults?
Adults
97
Describe the complications associated with rubella infection in pregnant women
Severe congenital defects
98
How is rubella prevented – what type of vaccine?
Live attenuated vaccine
99
What types of patients should NOT receive the rubella vaccine? (2)
- Pregnant women
- Immunocompromised patients
100
What family does the hepatitis C virus belong to?
Flaviviruses
101
Is hepatitis C a chronic or an acute disease?
Chronic
102
Hepatitis C is a ______ virus
Bloodborne
103
Is hepatic cancer a possible complication of hepatitis C?
YES
104
What is the function of antivirals in treating hepatitis C?
Reduce the number of viruses
105
Is there a vaccine for hepatitis C?
NO
