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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
RNA dependent DNA polymerase
enzyme needed for retroviral replication
26
examples of positive sense RNA viruses
picornaviruses: (poliovirus, hep C, hep A)
27
negative sense RNA
orthomyxovirus: influenza
28
double stranded RNA
rotavirus (required capsid because is targeted by the immune system)
29
retorvirus
HIV, SIV , HTLV
30
negative sense RNA
paramyxoviruses (mumps, measles, parainfluenza virus, RSV)
31
integrase
is a viral enzyme
32
flaviviruses
HCV (+) ss, enveloped
33
orthomyxoviruses
influenza, enveloped, - ss
34
coronaviruses
SARS, enveloped, + ss
35
tissue tropism
the cell or tissue type that supports replication of a given virus
36
sequence of virus spread
implantation @ portal of entry, local replication and local spread, dissemination from the portal of entry, multiplication in target organs, shedding of virus
37
reason for clinical disease
is multiplication in the target organ
38
most commons sites of viral implantation
respiratory, GI, skin penetrating, and genital routes
39
viruses spread
extra and intracellularly
40
dissemination can occur through
viremia, neural dissemination, cell trafficking, and direct cell-cell spread
41
incubation period
the time between exposure to the virus and onset of disease
42
determinants of viral pathogenesis
access of the virus to the tissue, virus susceptibility, cell permissiveness
43
pathogenesis
results from disruption of normal cellular processes
44
influenza/polio virus
host shutoff phenomenon
45
hep c virus
persistent infection, liver disfunction
46
HIV/T
cell syncytium
47
factors contributing to viral diversity
mutation, recombination/reassortment, replication rate/number of progeny, selective pressure
48
DNA viruses have
proofreading polymerases and have one mutant per 100(0) genome copies
49
RNA viruses
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
quasispecies
dynamic distribution of related genomes
51
RNA viruses exist
near the "error threshold"
52
largest % chance of infection due to needle stick injury
hep b virus
53
3 main types of genetic recombination
1. independent reassortment, 2. homologous recombination, 3. breakage/re-joining *REQUIRE A CELL INFECTED BY 2+ VIRUSES
54
independent reassortment
segmented genomes -- causes antigenic SHIFT
55
homologous recombination
can result in a chimeric genome resistant to both antiviral drugs
56
breakage/rejoining
requires nucleic acid break or fragmentation. occurs mainly with DNA viruses and large RNA viruses
57
what does recombination do that point mutations cannot
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
RNA viruses
represent major human pathogens and are ubiquitous, are diverse, and are adaptive
59
circovirus
ss circular DNA, no envelope
60
parvovirus
single stranded
61
adenovirus
ds linear DNA, icosahedron, no envelope
62
herpesvirus
ds linear DNA, icosahedron, yes envelope
63
hepadnavirus
+ partial, - partial, icosahedral, enveloped
64
DNA virus that does not replicate in the nucleus
poxvirus
65
DNA viruses that replicate in the nucleus use
RNA Pol II (multiple promoters, alternative splicing, code from both strands)
66
hallmark of DNA viruses is
that the expression of viral genes and viral DNA synthesis occur in a strictly defined, reproducible pattern
67
IE protiens
parental DNA, transactivators, transcription induced by host factors and carried in virions
68
E protiens
parental DNA, DNA synthesis, (when host shutoff can occur), advantageous environment for viral replication
69
Late Proteins
progeny DNA, structural
70
Host DNA polymerase mediated
papilloma, parvo, only made during the s phase
71
viral polymerase mediated
adeno, herpes, pox
72
parvovirus
B19
73
transforming infection
type of infection in which cell proliferation is induced thereby leading to cancer
74
replication requires
a 3' primer (and goes 5'--->3')
75
bi-directional DNA synthesis
papoviruses, circular DNA
76
strand displacement
adenovirus
77
self priming
parvoviruses, ITR
78
rolling circle
herpes, RNA primers needed
79
Late phase includes
late gene expression, down regulation of early gene expression, induction of CPE
80
CMV infection
inclusion bodies
81
types of infection
latent (HSV, varicella), chronic (hep B, HIV, hepadna), acute (flu, hep A, adeno), slow (JCV)
82
abortive infection
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
transforming infection
DNA alters the growth regulation of infected cells (papilloma, EBC) - usually oncogenesis is a mistake
84
parvovirus
DNA non enveloped, small, need helper virus (dependovirus +herpes, B19+dividing cells)
85
papovaviruses
DNA, non enveloped, icosahedral, ds circular 9papilloma, polyoma, narrow host cell range)
86
HPV
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
polyamoaviruses
DNA, BK, JC, MCV
88
adenovirus
non enveloped linear dsDNA (pink eye, hemorrhagic cystitis)
89
herpes
enveloped, large linear dsDNA, icosahedral, herpes is forever, tegument layer
90
acyclovir
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
hepadnavirus
occupational risk for health care workers, ~90 day incubation, cirrohis, mixed ssDNA/dsDNA
92
pox virus
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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