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Virus > Intro > Flashcards

Intro Flashcards

1
Q

Fundamental properties

A
  • filterable agents
  • RNA or DNA genome
  • obligate intracellular parasite
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2
Q

Classification criteria

A
  • Nature of nucleic acid
  • Symmetry of the capsid
  • Envelope (+/-)
  • Size
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3
Q

size range

A

20nm - 300nm

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4
Q

smallest virus (DNA/RNA)

A

~25 nm
DNA Parvovirus
RNA Picornavirus

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5
Q

largest virus

A

DNA poxvirus ~300 nm

RNA paramyxovirus

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6
Q

DNA Viruses, Genome

A 
Parvo, SS, linear
Hepadna, DS, circular
Papilloma, Ds, circular
Polyoma, DS, circular
Adeno, DS, linear
Herpes, DS, linear
Pox, DS, linear
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7
Q

RNA Viruses with

SS + Genome

A 
Picorna, SS, +
Calici, SS, +
Astro, SS, +
Toga, SS, +
Flavi, SS, +
-----
Retro SS + (two identical
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8
Q

RNA Viruses with

SS - Genome

A 
Rhabdo, SS, -
Paramyxo, SS, -
Orthomyxo, SS -
Filo, SS -
Arena, SS -
Bunya, SS -
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9
Q

RNA Virus with

DS Genome

A

Reo, DS +/-

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10
Q

Capsid structure

A

Symmetry - icosahedral or helical

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11
Q

capsid definition

A

protein coat surrounding nucleic acid

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12
Q

capsomer definition

A

repeating protein subunits making up capsid

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13
Q

protomer definition

A

polypeptide chains that make up the capsomers

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14
Q

helical capsids are composed of _____

A

helical capsids are composed of multiple copies of a single kind of protein subunit in a close-packed helix

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15
Q

Icosahedral capsid symmetry (faces, arrangement)

A

20 triangular faces

5:3:2 symmetry (referring to folds)

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16
Q

virion definition

A

the complete virus particle

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17
Q

nucleocapsid

A

capsid proteins associated with the viral nucleic acid

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18
Q

nucleoprotein

A

proteins associated with the viral nucleic acid

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19
Q

viral envelope composed of…

A

lipids, proteins, glycoproteins

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20
Q

what are spikes?

A

virus encoded envelope proteins that serve as viral attachement proteins

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21
Q 
What kind of capsid?
Adenovirus
Herpes
Influenza
HIV
Bacteriophage
A

Adenovirus - naked iocosahedral

Herpes - enveloped icosahedral

Influenza - enveloped helical

HIV - enveloped icosahedral

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22
Q

What are prions

A

abnormal, pathogenic, transmissible agents that are able to induce abnormal folding of normal cellular proteins

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23
Q

Prion diseases

A

…usually rapidly progressive and ALWAYS fatal.

  • CJD
  • vCJD (variant)
  • Gerstmann-Stausler-Scheinker
  • Fatal Familial Insomnia
  • Kuru
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24
Q

CJD

A

Creutzfeldt - Jacob
Spontaneous transformation of normal proteins into abnormal prions.
Risk of transmission with improperly sterilized instruments.

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25
Q

vCJD

A

variant of CJD

Bovin spongiform encephelopathy (BSE)

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26
Q

How do viruses gain entry into host cells

A

1) Fusion with cell membrane
• At cell membrane
• In an endosome

2) Receptor-Mediated endocytosis

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27
Q

Where are viral receptors found?

A
  • they’re usually normal cell surface components (CD4 to gp120)
  • generally requires coreceptor (CCR5/CXCR4 to gp41)
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28
Q

describe general model of replication

A
  • attachment
  • penetration
  • uncoating
  • replication
  • transcription/translation
  • assembly/maturation
  • release
29
Q

How are RNA virus genomes synthesized???

A

RNA viruses genomes encode their own Polymerase to create a strand of mRNA to be read by cellular machinery…

viral polymerase creates RNA from RNA

retroviruses are the exception (vRNA -> DNA, inserted into host)

30
Q

(+) vs (-) RNA polymerase use

A

(+) RNA viral genome can be directly transcribed by cellular machinery into viral proteins… one of these is viral polymerase

(-) RNA viral genome must be converted to (+) strand of RNA before transcription… viral polymerase is included in the viral particle.

31
Q

RNA virus replication generally occurs in _____. DNA virus replication generally occurs in ____, which allows for _____.

A
  • the cytoplasm (except retrovirus and influenza)
  • the nucleus (except poxvirus)
  • insertion into genome and host cell transformation
32
Q

DNA virus life cycle

A 
Attachment
Entry
Uncoating
MOVE TO NUCLEUS
GENE EXPRESSION (staged)
Replication
Assembly
Release (bud with nuclear membrane envelope)
33
Q

Viral release modes (naked vs enveloped)

A

Naked - lysis of cell (death)

Enveloped - budding through cell membrane (may spare cell)

34
Q

AIDS caused by

35
Q

Hepatitis caused by

A

HAV-HEV
CMV
EBV

36
Q

Cancer

A 
HPV
HBV, HCV
EBV
HHV-8
HTLV-1
37
Q

Encephalitis

A 
HSV
togaviruses
flaviviruses
rabies
picornaviruses
38
Q

Meningitis

A

enteroviruses
mumps
HSV-2
VZV

39
Q

GI Tract disease

A

rotaviruses
caliciviruses
adenoviruses (40, 41)

40
Q

Common cold

A

rhinoviruses
coronaviruses
adenoviruses

41
Q

Lower respiratory tract infections

A

influenza
parainfluenza
ReSV
adenoviruses

42
Q

Congenital & neonatal infections

A 
CMV
parvovirus B19
rubella
HSV
HIV
lymphocytic choriomeningitis
43
Q

Respiratory transmission

A

localized: influenza, common cold (rhino, corona, adeno)
disseminated: varicella-zoster, measles

44
Q

Fecal-oral transmission

Localized: 4

A

Localized: 4

Norovirus, Rotovirus, Astrovirus, Adenovirus

45
Q

Fecal-oral transmission Second site

A 
Second site: 
Picorna family
    -Enteroviruses
       -Polio
       -Coxsackie
       -Echovirus
       -Enterovirus
    -Hepatitis A

Hepatitis E

46
Q

Enterovirus secondary viremia - Meninges

A

Meninges: Echo, Polio, Coxsackie A

47
Q

Enterovirus secondary viremia - liver

A

Liver: Hep-A

48
Q

Enterovirus secondary viremia - Skin

A

Skin: Echo, Hep-A

49
Q

Enterovirus secondary viremia - muscle

A

Muscle: Echo, Cox A/B

50
Q

Enterovirus secondary viremia - Brain

A

Brain: Polio, Coxsackie

51
Q

Norovirus is the frequent cause of acute disease outbreaks on ____, and in ____/____

A

cruise ships

daycare centers / nursing homes

52
Q

Rotavirus causes 50% of ___ ___ in infants and children under 2 yrs

A

acute gastroenteritis

53
Q

Chronic viral diseases

A

HIV
Hep-B
Hep-C
HTLV-1

54
Q

Emerging viral infections caused by viruses that ___, ___, ___

A

1) continue to find vulnerable pops
2) continue to evolve
3) introduced from other species (zoonoses)

55
Q

What’s a dang quasispecies?
How does it happen?
Example?

A

Heterogenous group of sequences clustering around a consensus.

RNA polymerase lacks proofreading allowing for many mutation opportunities

HIV and influenza

56
Q

Zoonoses types and their vectors

A

Arbovirus (arthropod)
Rabies (bats, coons, dogs)
Hantavirus (deer mouse)
Pox virus

57
Q

Best tool for controlling viruses?

A

Prophylaxis

  • vaccines
  • universal precautions
  • education**
58
Q

Lytic vs Persistent infections

A

Lytic kill the cell through various mechanisms

Persistent do not cause cell death... may be:
chronic
latent
recurrent
transforming
59
Q

Syncytia is ___…

… for example _____

A

a mass of cytoplasm containing several nuclei

HIV, herpesvirus, Respiratory Syncytial Virus (a paramyxovirus)

60
Q

How is a virus detected after cultivation?

A

Cytopathic effects

Immunofluorescence

Hemadsorption / hemagglutination

61
Q

Cytopathic effects include:

A

Cytopathic effects

  • rounding / detachment
  • syncytia
  • shrinkage
  • increased refractility
  • aggregation
  • lysis
62
Q

Describe hemagglutination

example?

A

Many viral proteins bind to erythrocytes, and causes clumping

Flu is an example .. H in H1N1 means hemagglutination

63
Q

Criteria for diagnosing a primary infection through serology

A
  • at least 4x increase in titer of IgG or total antibody between acute and convalescent sera
  • Presence of IgM
  • Seroconversion
  • a SINGLE high titer of IgG, though very unreliable

*** usefulness depends on individual virus

64
Q

Serology works best / worst for:

A

Best: rubella / hep-a, because symptoms coincide with Ab titers

Worst: resp. / diarrheal, because clinical presentation occurs before Ab titers

65
Q

Serology and HIV

A

HIV produces clinical disease years after seroconversion… presence of Ab is enough to make definitive diagnosis

66
Q

Diagnosis through direct examination is made by viewing

A

inclusion bodies in histological slide

67
Q

Detection of viral nucleic acid and antigens is used for____

A

screening for blood transfusion

68
Q

Detection of viral antigens is done with ___

69
Q

Viral nucleic acid is detected using

A

Gene chip (Virochip)

Virus (3 decks)

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