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Fundamentals 1 > Viruses > Flashcards

Viruses Flashcards

1
Q

papovavirus

A

circular dsDNA

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2
Q

parvovirus

A

ss linear DNA

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3
Q

circovirus

A

circular ssDNA, smallest autonomously propagated virus

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4
Q

capsomeres

A

protein subunits that assembled together to form a capsid

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5
Q

icosahedral symmetry

A

high level of structural integrity, 20 equilateral triangles

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6
Q

4 examples with icosahedral symmetry

A

adenovirus, poliovirus, hep a, hep e

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7
Q

the virus lifecycle

A

attachment, penetration, un-coating, replication, assembly, release FOLLOW A WELL ORDERED SERIES OF TEMPORAL EVENTS

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8
Q

three types of viral penetration: fewest to most layers

A

fusion, translocation, endocytosis (this is an energy dependent step)

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9
Q

when is the beginning of the “eclipse” phase?

A

uncoating

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10
Q

viruses

A

have a strict dependence on host cell structural and metabolic components

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11
Q

range of virus sizes

A

20-30 nm (picorna) —> 300 nm (pox)

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12
Q

virion

A

the complete extracellular structure that transmits the infection

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13
Q

double stranded RNA

A

is highly unusual

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14
Q

nucleocapsid

A

the protein covered genome

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15
Q

envelope

A

resembles cellular membranes. consists of lipid bilayer, proteins, and glycoproteins

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16
Q

antisense strand mRNA

A

require virion associated polymerase activity

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17
Q

how many virus families infect humans?

A

21 (they are not alive and therefore do not fall on the tree of life)

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18
Q

the single most important classification of animal viruses

A

genomic nucleic acid

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19
Q

hep a-e

A

are all in different virus families

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20
Q

current virus classification strategy

A

genome composition, genome structure and organization, and morphology (nucleocapsid architecture)

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21
Q

species for the vaccine for smallpox

A

vaccinia virus

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22
Q

helical symmetry

A

a type of morphology (identical protein subunits, protomers, self assemble into a helical array surrounding the nucleic acid (rigid highly elongated rods or flexible filaments

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23
Q

initiation of infection

A

attachment, penetration, un-coating

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24
Q

replicase

A

complex of viral proteins and/or host proteins required for viral nucleic acid replication (includes viral polymerase and co factors)

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25
Q

RNA dependent DNA polymerase

A

enzyme needed for retroviral replication

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26
Q

examples of positive sense RNA viruses

A

picornaviruses: (poliovirus, hep C, hep A)

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27
Q

negative sense RNA

A

orthomyxovirus: influenza

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28
Q

double stranded RNA

A

rotavirus (required capsid because is targeted by the immune system)

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29
Q

retorvirus

A

HIV, SIV , HTLV

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30
Q

negative sense RNA

A

paramyxoviruses (mumps, measles, parainfluenza virus, RSV)

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31
Q

integrase

A

is a viral enzyme

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32
Q

flaviviruses

A

HCV (+) ss, enveloped

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33
Q

orthomyxoviruses

A

influenza, enveloped, - ss

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34
Q

coronaviruses

A

SARS, enveloped, + ss

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35
Q

tissue tropism

A

the cell or tissue type that supports replication of a given virus

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36
Q

sequence of virus spread

A

implantation @ portal of entry, local replication and local spread, dissemination from the portal of entry, multiplication in target organs, shedding of virus

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37
Q

reason for clinical disease

A

is multiplication in the target organ

38
Q

most commons sites of viral implantation

A

respiratory, GI, skin penetrating, and genital routes

39
Q

viruses spread

A

extra and intracellularly

40
Q

dissemination can occur through

A

viremia, neural dissemination, cell trafficking, and direct cell-cell spread

41
Q

incubation period

A

the time between exposure to the virus and onset of disease

42
Q

determinants of viral pathogenesis

A

access of the virus to the tissue, virus susceptibility, cell permissiveness

43
Q

pathogenesis

A

results from disruption of normal cellular processes

44
Q

influenza/polio virus

A

host shutoff phenomenon

45
Q

hep c virus

A

persistent infection, liver disfunction

46
Q

HIV/T

A

cell syncytium

47
Q

factors contributing to viral diversity

A

mutation, recombination/reassortment, replication rate/number of progeny, selective pressure

48
Q

DNA viruses have

A

proofreading polymerases and have one mutant per 100(0) genome copies

49
Q

RNA viruses

A

do not have a proofreading function and produce one mutation per genome cope (leads to the generation of ‘escape variants’ and is problematic for development of antiviral therapies and vaccines)

50
Q

quasispecies

A

dynamic distribution of related genomes

51
Q

RNA viruses exist

A

near the “error threshold”

52
Q

largest % chance of infection due to needle stick injury

A

hep b virus

53
Q

3 main types of genetic recombination

A
  1. independent reassortment, 2. homologous recombination, 3. breakage/re-joining *REQUIRE A CELL INFECTED BY 2+ VIRUSES
54
Q

independent reassortment

A

segmented genomes – causes antigenic SHIFT

55
Q

homologous recombination

A

can result in a chimeric genome resistant to both antiviral drugs

56
Q

breakage/rejoining

A

requires nucleic acid break or fragmentation. occurs mainly with DNA viruses and large RNA viruses

57
Q

what does recombination do that point mutations cannot

A

juxtapose things that would have a low probability of meeting otherwise, juxtapose viral genomes with limited homology (intertypic recombination), transduce sequences from nonhomologous genomes (low frequency)

58
Q

RNA viruses

A

represent major human pathogens and are ubiquitous, are diverse, and are adaptive

59
Q

circovirus

A

ss circular DNA, no envelope

60
Q

parvovirus

A

single stranded

61
Q

adenovirus

A

ds linear DNA, icosahedron, no envelope

62
Q

herpesvirus

A

ds linear DNA, icosahedron, yes envelope

63
Q

hepadnavirus

A

+ partial, - partial, icosahedral, enveloped

64
Q

DNA virus that does not replicate in the nucleus

A

poxvirus

65
Q

DNA viruses that replicate in the nucleus use

A

RNA Pol II (multiple promoters, alternative splicing, code from both strands)

66
Q

hallmark of DNA viruses is

A

that the expression of viral genes and viral DNA synthesis occur in a strictly defined, reproducible pattern

67
Q

IE protiens

A

parental DNA, transactivators, transcription induced by host factors and carried in virions

68
Q

E protiens

A

parental DNA, DNA synthesis, (when host shutoff can occur), advantageous environment for viral replication

69
Q

Late Proteins

A

progeny DNA, structural

70
Q

Host DNA polymerase mediated

A

papilloma, parvo, only made during the s phase

71
Q

viral polymerase mediated

A

adeno, herpes, pox

72
Q

parvovirus

A

B19

73
Q

transforming infection

A

type of infection in which cell proliferation is induced thereby leading to cancer

74
Q

replication requires

A

a 3’ primer (and goes 5’—>3’)

75
Q

bi-directional DNA synthesis

A

papoviruses, circular DNA

76
Q

strand displacement

A

adenovirus

77
Q

self priming

A

parvoviruses, ITR

78
Q

rolling circle

A

herpes, RNA primers needed

79
Q

Late phase includes

A

late gene expression, down regulation of early gene expression, induction of CPE

80
Q

CMV infection

A

inclusion bodies

81
Q

types of infection

A

latent (HSV, varicella), chronic (hep B, HIV, hepadna), acute (flu, hep A, adeno), slow (JCV)

82
Q

abortive infection

A

is not the same thing as an asymptomatic one. the infection fails to proceed, no virus is produced, but CPE may still result due to host immune response or activity of viral gene products

83
Q

transforming infection

A

DNA alters the growth regulation of infected cells (papilloma, EBC) - usually oncogenesis is a mistake

84
Q

parvovirus

A

DNA non enveloped, small, need helper virus (dependovirus +herpes, B19+dividing cells)

85
Q

papovaviruses

A

DNA, non enveloped, icosahedral, ds circular 9papilloma, polyoma, narrow host cell range)

86
Q

HPV

A
  1. infection of basal epithelial layer, 2. amplification of episomal DNA, 3. maintenance replication in differentiating cels, 4. productive viral replication in differentiated cells
87
Q

polyamoaviruses

A

DNA, BK, JC, MCV

88
Q

adenovirus

A

non enveloped linear dsDNA (pink eye, hemorrhagic cystitis)

89
Q

herpes

A

enveloped, large linear dsDNA, icosahedral, herpes is forever, tegument layer

90
Q

acyclovir

A

ingested, injected, topical ointment, highly effective against HSV1 and 2, pro drug, TK phosphorylation in cell (triphosphate form generated in infected cells), guanine nucleotide terminated DNA synthesis (no 3’ OH)

91
Q

hepadnavirus

A

occupational risk for health care workers, ~90 day incubation, cirrohis, mixed ssDNA/dsDNA

92
Q

pox virus

A

enveloped, dsDNA linear, REPLICATES IN CYTOPLASM, no need for nucleus, variola virus (small pox), vaccinia virus (cowpox-like vaccine)

Fundamentals 1 (4 decks)

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