Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL 4010 Virology > Flaviviruses > Flashcards

Flaviviruses Flashcards

1
Q

Where did faviviridae get its name from

A

flavus: Latin for yellow (cuz it causes yellow fever)

Dengue Hemorrhagic fever, tick borne encephalitis, West Nile virus, HCV, Zika virus
(animal swine fever and bovine viral diarrhea)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

3 genera

A
  1. flavivirus: infects humans monkeys bats and birds
  2. pesstivirus: infects pigs, cattle ruminants (plauge)
  3. hepacivirus: infects humans (HCV) liver
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Characteristics of Flaviviruses (5)

A
  1. mosquito/tick transmitted
  2. major envelope protein parallel to lipid membrane
  3. proteins synthesized as single poly protein
  4. pestivirus and hepacivirus have internal ribosomal entry site to begin protein synthesis
  5. assembles by budding fromER and released by exocytosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Flaviviruses genome and structure

A
  1. Spherical nucleocapsid
  2. Enveloped
  3. Envelope glycoproteins have icosahedral symmetry
  4. Linear +ve sense ssRNA
  5. 5’ cap
  6. NO Poly A tail
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Flaviviruses receptor preference

A
  • interacts with many cell surface particles depending on host (only few receptors have been characterized )
  • Antibody enhancement: non-neutralizing antibodies facilitate virus entry
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does Flaviviruses enter and fuse with the host

A

1- virus internalized via clathrin-coated pits
2- trafficked to pre-lysosomal endocytic compartment with low pH (inducing factor)
3- virus fuses with host membrane and nucleocapsid is released
** efficiency depends on the lipid composition of the membrane **
more cholesterol = more fusion

viral genome directly assembles for translation upon entry into host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Flaviviruses genes and proteins

A

genome translated as a single polyprotein (with 10 proteins) that then undergoes proteolytic cleavage
1 capsid proteins
2 envelope proteins
7 NS proteins (non-structural)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is primary determinant of Flaviviruses infectivity?

A

efficiency of genome translation
- viral genome translates directly (+ve)
- single long ORF and single polyprotien
- cleaved into individual proteins by viral protease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Flaviviruses RNA replication

A
  • semi-conservative
  • occurs on cytoplasmic membranous web
  • makes -ve sense RNA strand which acts as template for new +ve strand which then gets packaged
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Flaviviruses assembly and release

A
  • assembly and RNA replication are coupled
  • core protiens interact with viral genome and make nucleocapsid precoursor
  • gets envelope by budding from ER (fully formed virions in ER with rapid assembly)
    -passes through secretory pathway and gets released from cell surface (buds from host cell? or lytic?)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Yellow fever (signs and symptoms)

A

initially asymptomatic but then fever, muscle and back and head pain, loss of appetite and nausea

  • some people enter 2nd stage after 24hr after recovering from initial stage and then leads to liver and kidney failure (dark urine) and then jaundice and then 50% die after 7-10 days
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

primary reservoir for yellow fever

A

non-human primates
(human to human or primate to human transmission through intermediate mosquito vector)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Yellow fever treatment

A

early supportive care:
- treatment of dehydration
- treatment of co-occuring bacterial infection
- no specific antiviral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

yellow fever prevention

A
  1. vaccination (single dose = life long immunity, cheap, oldest live attenuated virus)
  2. vector control (control mosquito population and personal protection)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Dengue Virus (the hemorrhagic flavivirus) transmission

A

monkeys are reservoir host
mosquitos transmit it (AGAIN)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Dengue Virus symptoms

A

sudden onset of generalized symptoms: skin rash, high fever, headache, retroocular pain, back pain, flushing

increase in severity overtime, can get second phase (hemorrhagic stage shock syndrome)

17
Q

Dengue hemorrhagic stage/shock syndrome

A

increase in initial stage symptoms :
anorexia, weakness, decreased pulse, respiratory problems, rash spread to limbs, less WBC and platelet count

hemorrhagic: intestinal bleeding, vascular leaking, ogham failure (death 8-24hrs)

18
Q

Dengue virus immunity

A

there are many serotypes

if you get one, ur protected against it for life, but u have INCREASED RISK of other serotypes

Antibody-dependant enhancement: memory B cells and T cells can bind to other serotypes and help them get into cells

19
Q

Dengue virus treatment

A
  • no antiviral :(
  • management of symptoms (but not NSAID cuz it can increase bleeding)
20
Q

Dengue virus prevention

A
  1. vector control (control of mosquitos and personal protection)
  2. vaccine?? can make it worse? but Dengvaxia
21
Q

Dengvaxia

A

only given if you had confirmed prior infection (to prevent vaccine from making it worse)
approved by WHO for ppl 9-16 years in endemic regions

22
Q

Neurotrophic Falviviruses :

A

Japanese Encephalitis Virus
West Nile Virus
Zika Virus

23
Q

Symptoms of Japanese Encephalitis and West Nile Virus

A

most asymptomatic
both: headache vomiting seizures, stiff neck, confusion (JEV:fever, WNV:rash)
JEV: 30% fatality
WNV: 10% fatality

24
Q

JEV has many reservoirs and can undergo amplification in

A

Swine

25
Q

WNV mostly carried in

A

Birds ( cuz its asymptomatic can be carried in organs and blood given to immunosuppressed people and killing them, was not screened for like HIV is now)

26
Q

Treatment of Japanese Encephalitis and West Nile Virus

A

no treatment
supportive care if hospitalized

27
Q

Prevention Japanese Encephalitis and West Nile Virus

A

JEV: vaccine 90% effective
WNV: none for humans (only for horses)

28
Q

Zika Virus: where?

A

the new and shiny flavivirus
2016 - Brazil outbreak

29
Q

what cells does Zika virus effect?

A

dermal fibroblasts (by mosquito bite)
epidermal keratinocuyes
immature dendritic cells
can be taken by lymph and cause symptomatic

30
Q

Zika virus symptoms

A

Not abrupt, generalized symptoms (headache, fever, rash, arthritis, fatigue)

31
Q

Zika virus complication 1:

A

Guillian-Barre Syndrome:
- autoimmune: body’s immune system starts attacking neuron’s
- pin and needle sensations, weakness, unsteady walking, eye facial difficulty, bladder control, bowel function, breathing

32
Q

Zika virus complication 2:

A

Microcephaly: head smaller than expected due to improper brain development in utero
- seizures, intellectual disabilities, balance issues, swallowing issues, heading and vision loss

33
Q

Zika transmission

A
  • mosquito transmission
  • can be transmitted sexually or from mom to baby through placenta or breast milk
34
Q

Zika treatment

A
  • no antivirals :(
  • vaccine IN PROGRESS
  • management of symptoms (pain meds, antihistamine for rash, and fluid intake)
35
Q

Hepatitis C virus fun facts:

A
  • one of the first viruses to be discovered using modern tech (cDNA cloning of viral genome)
  • used to be called non A non B hepatitis
36
Q

Hepatitis C Virus (HCV) symptom

A
  • causes acute/chronic hepatitis (could also cause hepatocellular carcinoma HCC)
  • there is curative drugs!*
    *inhibits the enzymes that the virus codes for
  • can develop into chronic hepatitis if left untreated (but its RNA so it doesn’t integrate, but the viral genome just gets maintained)
  • transmitted by blood transfusion, needles, drug abuse nasal inhalation and possibly sexual contact (NOT MOSQUITOS unlike others)
  • no vaccine available
37
Q

Why is HCV vaccine so difficult

A
  1. money
  2. virus diversity (high mutation rate, immune system can’t clear it on its own so hard with vaccine)
    3.lack of a good animal model (can’t use chimpanzees anymore)
38
Q
A

BIOL 4010 Virology (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions