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Virology > Exam IV: Lecture 12 > Flashcards

Exam IV: Lecture 12 Flashcards

1
Q

What are some examples of plus-strand RNA viruses? (7)

A
  1. Encephalitis
  2. Hapatitis
  3. Polyarthritis
  4. Yellow Fever
  5. Dengue fever
  6. Poliomyelitis
  7. Common Cold
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2
Q

What are the 6 families of +RNA viruses?

A
  1. Piconaviridae
  2. Caliciviridae
  3. Astroviridae
  4. Togaviridae
  5. Flaviridae
  6. Coronaviridae
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3
Q

What family is the poliovirus a part of?

A

Picornavirus

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4
Q

How large is the genome of poliovirus?

A

7-8.5 kb

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5
Q

How is poliovirus translated? What is unique about it?

A

Polyprotein

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6
Q

How is poliovirus transmission?

A

Oral/Fecal Transmission

Shed in weeks for feces

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7
Q

What is the main pathology of poliovirus?

A

It is neurotropic

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8
Q

Causes flaccid paralysis in what percent of cases?

A

1%

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9
Q

Is poliovirus enveloped or nonenveloped?

A

Enveloped

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10
Q

What was the first vaccine for poliovirus made of? Who was it made by?

A

Poliovirus + formaldehyde to inactive the virus
Very few people got polio from the vaccine
1st tested on orphans
Salk

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11
Q

Tell me about the Sabin vaccine

A

Oral vaccine - drop on the tongue
Attenuated virus
Passed through a monkey

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12
Q

How many infections of poliovirus occur each year? How many result in hospitalizations?

A

5-10x10^6 infections/year

30-50,000 hospitalizations

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13
Q

What are the main symptoms of poliovirus infection?

A

Can lead to meningitis, encephalitis, myocarditis

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14
Q

Occosionally, poliovirus can spread to what part of your body? Leading to what?

A 
Causes viremia (goes into blood)
Can infect the spinal cord and cause cell death > paralysis
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15
Q

Recovery in severe cases is quick/slow?

A

Slow

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16
Q

What is post-polio syndrome?

A

Muscle atrophy related to first infection which can last the rest of your life

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17
Q

What are the clinical symptoms and progression of poliomyelitis?

A

Oral > stomach > intestines > lymph nodes > blood > poliomyelitis > death of nuerons (severe cases) > patient recovers OR is paralyzed OR has inability to breath on their own (see iron lung)

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18
Q

What is the iron lung? How is it related to polio?

A

When polio enters the blood it can kill the neurons in the diaphragm > inability to breath
The iron lung is a giant box that creates a vacuum seal and effectively breaths for the patient

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19
Q

Is the genome of poliovirus linear or circular?

A

Linear

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20
Q

What is unique about the genome of poliovirus? (2)

A

VPg

5’NCR and 3’NCR (non-coding region)

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21
Q

What is the VPg required for in poliovirus?

A

The VPg is required to prime the synthesis of new genomes of poliovirus

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22
Q

What does the 5’NCR of poliovirus contain?

A

IRES

Internal ribosome entry site

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23
Q

Talk me through Genome replication of poliovirus

A

At 5’ end the RNA folds up because some pieces are complementary = IRES = recruits ribosome
VPg provides the OH group
It is CAP INDEPENDENT
Polyprotein is cleaved via autocatalysis because it in itself if a protease

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24
Q

What is the implication of cap-independent transcription of poliovirus?

A

Transcription can be immediate

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25
Where does the transcription and translation of poliovirus occur?
Everything happens in the cytoplasm
26
Can the original +RNA strand of poliovirus be directly translated?
No, you need ot make a -RNA strand first and then make complimentary +RNA strands
27
What is one defense poliovirus uses against the host?
Since poliovirus replication is a cap-independent process, it does not need the cap-binding protein of the ribosome complex (eIF-4G) so it cleaves eIF-4G making host translation impossible 1) host can't produce antiviral proteins 2) viral replication occurs at a higher rate since it gets to use all the machinary
28
What is the difference between the first Salk vaccine developed against poliovirus and the current vaccine being used?
???
29
What kind of vaccines are available against polio? How were they made?
Live attenuated through monkey | deactivated with formaldehyde?
30
What are the three genera of Flavivirus?
1. Flavivirus 2. Pestivirus 3. Hepacivirus
31
What is the most common flavivirus?
Yellow Fever Virus
32
Is flaviviruses enveloped?
Yes
33
How large is the genome of flaviviruses?
Small genome (9-11kb)
34
How are flaviviruses transmitted?
Arboviruses = spread via mosquitos and ticks
35
What are some diseases caused by Flaviviridae?
Hemorrhagic fever, Fever, encephalitis, arthralgia, rash
36
What is jaundice? How does it occur?
The dysfunction of the liver that leads to the build-up of bile salts under the skin > look yellow (ie yellow fever)
37
What are some viruses that are Flaviviridae? (4)
1. Yellow fever 2. Dengue 3. West Nile 4. Hepatitis C
38
What is the geographic distribution of the yellow fever virus?
Central Africa | High South America
39
Translation of flavivirus produces what?
Polyprotein that gets cleaved by cellular proteases (ex NS3)
40
What is the primary cell target (tropism) of yellow fever?
Lymphoid cells are the principal targets for early replication
41
Yellow fever binds to what protein found in the membrane of what cells?
CD155 protein | NK cells
42
What causes direct viral damage to the liver in yellow fever?
Viremia?
43
It is not uncommon for yellow fever to damage what two organs in addition to the liver?
Kidneys | Heart
44
Up to __% of severly affected persons without treatment will die from yellow fever
50
45
How many cases and deaths of yellow fever each year?
200,000 cases | 30,000 deaths
46
Why has the number of yellow fever cases increased over the past 2 decades? (5)
1. Declining population immunity 2. Deforestation 3. Urbanization 4. Population movements 5. Climate change
47
Is thre a cure for yellow fever?
No
48
What are the treatments for yellow fever?
Treatment is symptomatic
49
What is the best way to prevent yellow fever?
Vaccines!
50
What is the incubation period for yellow fever?
3-6 days
51
What are the symptoms of yellow fever?
Initially = high fever, malaise, headache, photophobia, nausea, vomiting Hemorrhagic disease = oozing at gums, black vomit, hematuria, disseminated intravascular coagulation
52
Febrile
fever
53
Fulminant
Severe and sudden onset
54
What is the mortality rate __% to __%
20-50%
55
What is the story of the Panama channel and yellow fever?
100,000 workers dying of yellow fever Army medical institute > put sick pt in mosquito net tent > expose healthy soldier to mosquitos > get sick Eliminate mosquitos = finish canal
56
What is the genome of the dengue virus? Size?
+ssRNA | 11kb
57
What is Dengue fever also known as?
Break-bone disease | Joint pain can least uears
58
How many people are infected with dengue every year?
50-100 million
59
How is dengue virus spread?
``` Via mosquitoes (aesesaejypti) the virus replicates in gut cells of mosquitoes ```
60
After being bitten by an infected mosquito, the incubation period is how long?
Up to two weeks
61
Does Dengue fever has a IRES?
Yes
62
What is antibody-dependent enhancement (ADE)? What virus does this occur in?
Occurs in Dengue fever Secondary infection > hemmoragic diesease (DHF) Primary infection > antibodies > 2nd infection with different glycoproteins > heterotypic Ab from previous infection bind > Ab cannot neutralize the virus particle >Ab+virus binds to monocyte/macrophage via Fcgamma receptor > is endocytosed = antibodies help the virus infect monocytes more efficiently > increase in overall replication > higher risk of severe dengue
63
Overall RNA viruses have caused diseases since antiquity
True
64
Poliovirus is close to being the second virus eliminated from nature
True
65
Yellow fever is still a threat, though vaccines exist
True
66
The range of Dengue virus is spreading with climate change as its vector range moves away from the tropics
True

Virology (22 decks)

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