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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
Q

Where does the transcription and translation of poliovirus occur?

A

Everything happens in the cytoplasm

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26
Q

Can the original +RNA strand of poliovirus be directly translated?

A

No, you need ot make a -RNA strand first and then make complimentary +RNA strands

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27
Q

What is one defense poliovirus uses against the host?

A

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
Q

What is the difference between the first Salk vaccine developed against poliovirus and the current vaccine being used?

A

???

29
Q

What kind of vaccines are available against polio? How were they made?

A

Live attenuated through monkey

deactivated with formaldehyde?

30
Q

What are the three genera of Flavivirus?

A
  1. Flavivirus
  2. Pestivirus
  3. Hepacivirus
31
Q

What is the most common flavivirus?

A

Yellow Fever Virus

32
Q

Is flaviviruses enveloped?

A

Yes

33
Q

How large is the genome of flaviviruses?

A

Small genome (9-11kb)

34
Q

How are flaviviruses transmitted?

A

Arboviruses = spread via mosquitos and ticks

35
Q

What are some diseases caused by Flaviviridae?

A

Hemorrhagic fever, Fever, encephalitis, arthralgia, rash

36
Q

What is jaundice? How does it occur?

A

The dysfunction of the liver that leads to the build-up of bile salts under the skin > look yellow (ie yellow fever)

37
Q

What are some viruses that are Flaviviridae? (4)

A
  1. Yellow fever
  2. Dengue
  3. West Nile
  4. Hepatitis C
38
Q

What is the geographic distribution of the yellow fever virus?

A

Central Africa

High South America

39
Q

Translation of flavivirus produces what?

A

Polyprotein that gets cleaved by cellular proteases (ex NS3)

40
Q

What is the primary cell target (tropism) of yellow fever?

A

Lymphoid cells are the principal targets for early replication

41
Q

Yellow fever binds to what protein found in the membrane of what cells?

A

CD155 protein

NK cells

42
Q

What causes direct viral damage to the liver in yellow fever?

A

Viremia?

43
Q

It is not uncommon for yellow fever to damage what two organs in addition to the liver?

A

Kidneys

Heart

44
Q

Up to __% of severly affected persons without treatment will die from yellow fever

A

50

45
Q

How many cases and deaths of yellow fever each year?

A

200,000 cases

30,000 deaths

46
Q

Why has the number of yellow fever cases increased over the past 2 decades? (5)

A
  1. Declining population immunity
  2. Deforestation
  3. Urbanization
  4. Population movements
  5. Climate change
47
Q

Is thre a cure for yellow fever?

A

No

48
Q

What are the treatments for yellow fever?

A

Treatment is symptomatic

49
Q

What is the best way to prevent yellow fever?

A

Vaccines!

50
Q

What is the incubation period for yellow fever?

A

3-6 days

51
Q

What are the symptoms of yellow fever?

A

Initially = high fever, malaise, headache, photophobia, nausea, vomiting
Hemorrhagic disease = oozing at gums, black vomit, hematuria, disseminated intravascular coagulation

52
Q

Febrile

A

fever

53
Q

Fulminant

A

Severe and sudden onset

54
Q

What is the mortality rate __% to __%

A

20-50%

55
Q

What is the story of the Panama channel and yellow fever?

A

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
Q

What is the genome of the dengue virus? Size?

A

+ssRNA

11kb

57
Q

What is Dengue fever also known as?

A

Break-bone disease

Joint pain can least uears

58
Q

How many people are infected with dengue every year?

A

50-100 million

59
Q

How is dengue virus spread?

A 
Via mosquitoes (aesesaejypti)
the virus replicates in gut cells of mosquitoes
60
Q

After being bitten by an infected mosquito, the incubation period is how long?

A

Up to two weeks

61
Q

Does Dengue fever has a IRES?

A

Yes

62
Q

What is antibody-dependent enhancement (ADE)? What virus does this occur in?

A

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
Q

Overall RNA viruses have caused diseases since antiquity

A

True

64
Q

Poliovirus is close to being the second virus eliminated from nature

A

True

65
Q

Yellow fever is still a threat, though vaccines exist

A

True

66
Q

The range of Dengue virus is spreading with climate change as its vector range moves away from the tropics

A

True

Virology (22 decks)

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