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MIMM 324 > Picornaviruses and togaviruses > Flashcards

Picornaviruses and togaviruses Flashcards

1
Q

Why did the polio pandemic started

A

because we started to get more clean and would get sanitation.
-kids before used to get it really fast while they were still drinking their mothers
-now adults got it later

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2
Q

how do you get polio

A

fecal oral

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3
Q

symptoms

A

-fever
-heachache
-vomitting
-diarrhea
-neck stiff
-pain
-death

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4
Q

What was the first vaccine for polio

A

-salks vaccine
-inactivated polio vaccine devceloped in hela cells
-needs to be refregiratred
-delivered by injection
-safe high potency
-lowkey annoying

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5
Q

Oral polio vaccine

A

-live attenuated virus
-not refrigerated

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6
Q

True or false: polio has no animal reservoir

A

true

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7
Q

True or false: polio is almost erradicated

A

true

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8
Q

True or false: polio is a pocornavirus

A

true

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9
Q

Stats about picornaviruses

A
  • Non-enveloped viruses
  • Icosahedral capsid
  • 25-30 nm in diameter
  • Genome: (+) ssRNA
  • Monopartite, linear
  • 7 - 8.5 kb in length
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10
Q

What was the first virus discovered?

A

-Foot and mouth disease: fmdv
-highly infectuous
-for animals that have cloves

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11
Q

True or false: HepA is a pocornavirus

A

true

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12
Q

Symptoms of HAV+how it is spreaded around

A

–nausea and vomiting
-Spread by diredt contact, food, beverages and cups and spoons
-from fecal matter

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13
Q

True or false: HAV is an acute infection

A

true
-most people can actually recover from the infection

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14
Q

True or false: the common cold is a picornavirus

A

true

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15
Q

do picornaviruses code for a polyprotein

A

true

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16
Q

how do picornaviruses get in?

A

integrins

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17
Q

where do viral receptors bind: picornaviruses

A

canyon

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18
Q

how many VP proteins do picornaviruses have

A

4
VP1-4

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19
Q

true or false: picornaviruses replicate in nucleus

A

false they do it in the cytoplasm

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20
Q

Entry and uncoating of picornaviruses

A

Some picornaviruses use receptor-mediated endocytosis
(rhinovirus, FMDV), while others (poliovirus) inject their viral
RNA directly across the plasma membrane

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21
Q

True or false: picornaviruses have a cap-dependent translation

A

false: independent
* Does not contain a 5’ cap
structure
* Must initiate translation in
a cap-independent
manner
* Internal Ribosomal Entry
Site (IRES) mechanism
* Allows viral translation
during host protein
synthesis shutoff

22
Q

What is the dilema of +ssran viruses

A

they have to turn off translation to start replication

23
Q

How do +ssran make the shift from translation to replication

A

they circularize
-which helps recruiting the proteins required like 3cd and PC which binds to the IRES

24
Q

True or false: Togavirus Replication Occurs
on Virus-induced Cellular Vesicles

A

false: it is picornaviruses
* Vesicles are induced by the viral proteins 2B, 2C and 3A
* Required for viral RNA synthesis
- nucleation site for replication complex formation
Vesicle formation in virus-infected cell

25
True or false: picornavirus replication induces SMVs and DMVs
* Early in infection - single- membrane vesicles (SMVs) containing dsRNA are derived from the ER and golgi * Later vesicles wrap around themselves to form double-membrane vesicles (DMVs)
26
How does viral packaging and assembly works? for picornaviruses
YOU BASICALLY HAVE ALL THE SUB UNITS AND THEN YOU EITHER put the virus in or you have the capsid around the rna
27
What was a system used for production of infectious polio in vitro
cdna that then you make rna and then put in cultured cells
28
Stats about togaviridae
* Toga (Latin = gown or cloak) - Two genera: Rubivirus (Rubella virus) and Alphavirus (27 members) * Enveloped viruses (icosahedral envelope) * Icosahedral capsid - 70 nm in diameter * Genome: (+) ssRNA - Monopartite, linear - 9-11 kb in length
29
Name 2 viruses that are part of the togaviridae fam
rubivirus and alphaviruses like chikunguya
30
true or false: rubella is an acute ibfection
true
31
how does rubella spreads
through the air or caughuing
32
who are the the hosts for rubella
humans
33
true or false: the us is rubella free
true
34
True or false: picornaviruses are arthropod borne viruses
false: it is alphaviruses
35
what are arthropod borne viruses
* Arthropod-borne viruses (Arboviruses) - Group of viruses transmitted by arthropod (insect) vectors - Replicate in both cold-blooded arthropods and warm- blooded vertebrate hosts (adaptable) - Infection in insects is often not cytopathic, but persistent * Arboviruses were initially classified together; but they have: - Distinct genome organization and replication strategies - Reclassified into different families: Togaviridae, Flaviviridae and Bunyaviridae
36
True or false: we are accidental hosts of alphaviruses
true Naturally it is between moquitoes and wild birds
37
how id chikuguya transmitted
Aedes aegypti and Aedes albopictus
38
what does chikungutya mean
disease that bends uo the joints
39
symoptoms of chikunguya
Symptoms: abrupt onset of fever, severe joint pain (may persist for weeks to years), arthritis (with joints exhibiting tenderness and swelling), skin rash, myalgia (esp. in lower back and leg muscles) - more rare: neurological features and cardiac manifestations, death (neonates, >65 yrs, and immunocompromised) -highly debitating=economic impacts
40
Where is chikunguya usually is
south america/asia/africa
41
true or false: togaviruses encode for polyproteins
true
42
which virus has extremely uniform particles
togaviruses 40 copies each of E2, E1, and Capsid proteins All have Icosahedral symmetry = Extremely uniform particles
43
where do togaviruses replicate
in the cytoplasm
44
cellular entry of toga viruses
* Cell receptors are unclear (mutations in E2 accumulate in culture that can alter receptor binding) - E2 can bind Laminin (rodent/primates) and Heparin Sulfate (upon passage in culture) * Virions enter cells by receptor-mediated endocytosis - pH drop in endosomes causes a conformational change in E1/E2 leading to membrane fusion and release of the nucleocapsid
45
non structural proteins of togaviruses translation
* Genomic RNA contains a 5’ methylated cap and 3’ poly-A tail * Nonstructural proteins (NSPs) are translated directly from the genome - Readthrough of a UGA codon occurs 10-20% of the time the complete P1234 polyprotein
46
-strand rna synthesis of togaviruses
Partially cleaved NSPs are responsible for negative-strand RNA synthesis aka p123 and nsp4
47
Temporal Regulation of Negative- and Positive-strand RNA Synthesis of togaviruses
* Partially (cis-) cleaved NSPs can catalyze negative-strand RNA synthesis and transcription of subgenomic mRNAs - Subgenomic mRNAs encode the structural proteins * Proteolytic processing (trans-cleavage) of NSPs results in positive-strand RNA synthesis
48
which viruses replication takes place on cytopathic vacuoles
togavirus * dsRNA spherules form at the plasma membrane * Internalization of these structures by the endo- lysosomal pathway results in formation of cytopathic vacuoles (CPVs)
49
Packaging, and assembly of togaviruses
Structural proteins are cleaved during translation and directed to different cellular locations - Capsids self cleave and bind to a packaging signal in the genomic RNA to form nucleocapsids - pE2, 6K and E1 are processed by host signal peptidase and furin protease in the ER - Further modification of envelope proteins occurs during translocation through the trans-golgi network on their way to the cell surface
50
true or false: togaviruses capsid proteins interact with the cytoplasmic tails of envelope proteins on the cell surface
true
51
how do togavirus virions exit the cell
by budding

MIMM 324 (26 decks)

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