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HELENP CBG VIROLOGY AND IMMUNITY > CBG Lecture 20: Viral diversity > Flashcards

CBG Lecture 20: Viral diversity Flashcards

(67 cards)

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1
Q

define virus

A

a small non cellular agent consisting largely of nucleic acid within protein coat and requiring a cell for reproduction`

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2
Q

what is a way in which viruses differ from eachother

A 
genome diversity 
ss or ds
DNA or RNA
circular or linear
\+ sense or -sense
segmented or nonsegm
life cycles
replication strategy
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3
Q

name some DNA viruses

A

herpes
pox
mimi

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4
Q

name some rna viruse

A

picorna
polio
rubella
HIV

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5
Q

is herpes virus dna/rna

A

dna

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6
Q

is polio dna/rna virus

A

rna

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7
Q

is mimivirus dna or rna virus

A

dna

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8
Q

what is max size of rna virus

A

30kbp

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9
Q

what is range of dna virus

A

3-800kb

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10
Q

which viruses tend to have overlapping genes

A

those with small genomes

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11
Q

is HIV rna or dna virus

A

rna

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12
Q

what is HIV genome size

A

9kb

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13
Q

how many strands are most rna viruses

A

single stranded

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14
Q

which RNa viruses are double stranded

A

reoviruses

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15
Q

what is unusual about reoviruses

A

they are RNA double stranded

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16
Q

what ssDNA viruses are there

A

some small viruses

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17
Q

whats unusual about parvoviruses

A

v. small SINGLE stranded dna virus

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18
Q

name a circular dsDNA virus

A

SV40

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19
Q

what is unusual about SV40 virus

A

has circular dsDNA genome

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20
Q

which viruses have lower error/mutation rate

A

dna viruses, because DNAP has proofreading arm

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21
Q

what is the effect of RNA viruses having a high mutation rate

A

every RNA virus is different so get quasispecies

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22
Q

what is a quasispecies

A

virus doesnt exist as single sequence but pool of sequences making it v difficult to make vaccines

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23
Q

why is it important for big viruses to be dsDNA

A

more stable therefore lower mutation rates

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24
Q

how can RNa viruses have genome that is mostly ss but with some ds

A

because can make ds by looping structures - secondary structures eg. hairpin

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25
in what direction does - sense viruses go
3' 5'
26
how do -sense viruses replicate
produce +sense mRNA before production of viral proteins | input RNA then to +RNA then to progeny RNA then to virions which are -sense 3'5'
27
what are polarity switches
from virion of -sense RNa back to +sense RNA
28
give example of segmented virus
influenza
29
give example of non-segment
retrovirus
30
give example of +sense non-segmented genome
retrovirus
31
what genome do retroviruses have
+sense non-segmented genome
32
how do nonsegmented viruses evolve
mutation | recombination
33
how do segmented viruses evolve
mutation recombination assortment
34
how many segments in influenza virus
7/8
35
when does antigenic shift occur
when RNA segment are exchnaged between viral strains in a secondary host no cross protective immunity to virus expressing a novel hemaglutinin
36
what microscope used to see viruses
EM
37
what is basic structure of a virus
genome (nucleic acid) surrounded by capsid eg.TMV
38
give example of virus which has genome surrounded by capsid
TMV
39
what does the capsid of a virus do
protect nucleic acid
40
how can virus capsid be assembled
self assembly - monomeric protein units produce spherical particles one or more capsid prteins:icosahedral formations
41
name some ds segmented RNA virus
reoviridae
42
name some nonsegmented negative strand rna virus
paramyxoviridae | filoviridae
43
name a segmented - rna virus
orthomyxoviridae | bunyaviridae
44
name a virus with an envelope
retrovirus: hiv
45
name some dna virus
circo/parvo/papoadeno/herpes/pox
46
name some host specific viruses
small pox and polio are human specific
47
name some human specific viruses
smallpox and polio
48
what is mortality rate of ebola
90%
49
for most viruses, how many viral cells do you need to get exposure to to contract it? whyh is ebola the exception
normally need 1000s virus eg.polio but with ebola need 1
50
define zoonotic
infectious diseases of vertebrates that can be naturally transmitted to humans eg.rabies
51
name a zoonotic virus
rabies | ebola
52
what is WNV
west nile virus
53
how is WNV transmitted
crow to crow transmission in caged birds by infected mosquitos
54
what is WNV vector
mosquitos
55
how do mosquitos become infected with WNV
when they bite birds infected with WNV
56
what are the dead end carriers of WNV
uhans - the virus is not sufficient to be transmitted back to the mosquito, thereby ending transmission cycle
57
why are humans dead end csarriers of WNV
because the virusin them is not sufficient enough to be transmitted ack to mosquto therefore ends the transmittion cycle
58
whats unusual about mimivirus
physically big and related to other dsDNA viruses
59
how many genes do mimiviruses contain | what is its genome size
900 | 1Mbp genome size
60
apart from mimivirus, what virus has next biggest genome size
poxvirus
61
how many genes does poxvirus contain
900
62
how can you eradicate a virs
need to be human specific, effective vaccine, need virus to produce symptoms, need antigenetically STABLE virus
63
name some asymptomatic viruses
WNV in some mamals | poliovirus
64
how old are RNA viruses
up to 3.5bn yrs old
65
what are similarities between HIV types 1&2
replicate in the nucleus contain 2 env proteins contain RT envelope fuses with cell membrane
66
how does adenovirus getinto host cell
endoctosed
67
how does influenza get into host cell
endocytosed then fuses with the endosome in a pH dependent manner

HELENP CBG VIROLOGY AND IMMUNITY (8 decks)

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