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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
Q

True or false: picornavirus replication
induces SMVs and DMVs

A
  • 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
Q

How does viral packaging and assembly works? for picornaviruses

A

YOU BASICALLY HAVE ALL THE SUB UNITS AND THEN YOU EITHER put the virus in or you have the capsid around the rna

27
Q

What was a system used for production of infectious polio in vitro

A

cdna that then you make rna and then put in cultured cells

28
Q

Stats about togaviridae

A
  • 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
Q

Name 2 viruses that are part of the togaviridae fam

A

rubivirus and alphaviruses like chikunguya

30
Q

true or false: rubella is an acute ibfection

A

true

31
Q

how does rubella spreads

A

through the air or caughuing

32
Q

who are the the hosts for rubella

A

humans

33
Q

true or false: the us is rubella free

A

true

34
Q

True or false: picornaviruses are arthropod borne viruses

A

false: it is alphaviruses

35
Q

what are arthropod borne viruses

A
  • 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
Q

True or false: we are accidental hosts of alphaviruses

A

true
Naturally it is between moquitoes and wild birds

37
Q

how id chikuguya transmitted

A

Aedes aegypti and Aedes albopictus

38
Q

what does chikungutya mean

A

disease that bends uo the joints

39
Q

symoptoms of chikunguya

A

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
Q

Where is chikunguya usually is

A

south america/asia/africa

41
Q

true or false: togaviruses encode for polyproteins

A

true

42
Q

which virus has extremely uniform particles

A

togaviruses
40 copies each of E2, E1, and Capsid proteins
All have Icosahedral symmetry
= Extremely uniform particles

43
Q

where do togaviruses replicate

A

in the cytoplasm

44
Q

cellular entry of toga viruses

A
  • 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
Q

non structural proteins of togaviruses translation

A
  • 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
Q

-strand rna synthesis of togaviruses

A

Partially cleaved NSPs are responsible for negative-strand RNA synthesis aka p123 and nsp4

47
Q

Temporal Regulation of Negative-
and Positive-strand RNA Synthesis of togaviruses

A
  • 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
Q

which viruses replication takes place on cytopathic vacuoles

A

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
Q

Packaging, and assembly of togaviruses

A

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
Q

true or false: togaviruses capsid proteins interact
with the cytoplasmic tails of envelope proteins on
the cell surface

A

true

51
Q

how do togavirus virions exit the cell

A

by budding

MIMM 324 (26 decks)

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