Central Dogma and Polio

Question 1

what are viruses?

Answer 1

obligate intracellular parasites

Question 2

what are the 2 was viruses can use host resources / machinery?

Answer 2

1. conform themselves to fit host machinery

2. conform host machinery to fit them

Question 3

DNA dependent DNA polymerase uses ___ to make ___

Answer 3

dsDNA; more dsDNA

Question 4

RNA polymerase uses ___ to make ___

Answer 4

dsDNA ; (+) ssRNA

Question 5

ribosomes translate +ssRNA into ___

Answer 5

amino acid sequence

Question 6

T/F virus genomes can be DNA or RNA

Answer 6

true

Question 7

the genomes of viruses can be diverse, but all most pass through a stage that resembles ___

Answer 7

mRNA

Question 8

why must all viruses go through a stage of resembling mRNA?

Answer 8

host protein synthesis can use it to make viral protein

Question 9

gene products (mostly proteins) are required for what 5 things?

Answer 9

1. replication of viral genome
2. assembly and packaging of genome particles
3. regulation and timing of replication cycle
4. modulation of host defence
5. spread to other cells and hosts

Question 10

what information is encoded by viral genomes?

Answer 10

protein products

Question 11

do viral genomes encode the complete protein synthesis machinery?

Answer 11

no

Question 12

do viral genomes encode proteins involved in energy production and membrane synthesis? [

Answer 12

no

Question 13

do viral genomes encode centromeres or telomeres?

Answer 13

no

Question 14

+ ssRNA viruses get directly translated into the cytoplasm (T/F)

Answer 14

ture

Question 15

how do polioviruses express their genes?

Answer 15

direct translation into cytoplasm

Question 16

how do polioviruses replicate their genomes?

Answer 16

viral RNA dependent RNA polymerase with dsDNA intermediates

Question 17

why don’t Polioviruses use host RNA dependent RNA polymerase?

Answer 17

because host cells don’t have them!

Question 18

would progeny viruses be made if naked RNA into a host cell? Why/why not?

Answer 18

yes because the genome is already translated

Question 19

the amino terminal makes a lot of ___ proteins

Answer 19

structural

Question 20

the carboxyl terminal makes a lot of ___ proteins

Answer 20

enzymatic

Question 21

T/F polyproteins can be cleaved by either host or viral proteases into the full complement of viral proteins

Answer 21

true

Question 22

why do proteases make a good drug target? (2)

Answer 22

1. if proteins are not made, the virus can’t replicate

2. unique (not going to accidentally target host)

Question 23

disadvantage for virus relying on host proteases?

Answer 23

host is in control

Question 24

poliovirus and HCV both encode RNA dependent RNA polymerase at which end of the genome?

Answer 24

3’

Question 25

why is there an RNA dependent rna polymerase on the 3' end of the polio genome?

Answer 25

it puts it in the perfect spot to bind to the rna and and start replication in the 5' direction to make the complementary strand

Question 26

T/F RDRP (rna dependent rna polymerase) is a drug target

Answer 26

true

Question 27

the poliovirus causes what disease?

Answer 27

poliomyelitis

Question 28

where does poliovirus live?

Answer 28

in the water

Question 29

t/f the infection of poliomyelitis used to be common, but the infection was not

Answer 29

true

Question 30

__% of cases of poliomyelitis are asymptomatic

Answer 30

95

Question 31

__% of poliomyelitis cases spread to secondary tissues and cause flu-like symptoms

Answer 31

5

Question 32

__% of poliomyelitis cases enter the central nervous system and results in selective destruction of motor neurone

Answer 32

less than 1

Question 33

what are the 2 effective vaccines for poliomyelitis?

Answer 33

1. sabin (oral) | 2. stalk (intradermal)

Question 34

how is the poliovirus grown and inactivated to make the stalk vaccine?

Answer 34

grown in kidneys of monkeys; inactivated by formalin

Question 35

how is the poliovirus grown and attenuated in the sabin vaccine?

Answer 35

grown at subphysiologic temperatures, which causes the virus to undergo spontaneous mutations

Question 36

t/f the attenuated poliovirus of the oral sabin vaccine can replicate in the gut

Answer 36

t

Question 37

the oral Sabin vaccine establishes what type of immunity?

Answer 37

mucosal

Question 38

what makes the erradication of poliomyelitis possible?

Answer 38

no animal reservoir

Question 39

poliovirus binds to what receptor on the cell surface of a host?

Answer 39

CD155 (PVR)

Question 40

what is the normal function of CD155 PVR?

Answer 40

cel-cell contact between epithelial cells

Question 41

once bound to the PVR, how does the poliovirus enter the host cell?

Answer 41

endocytosis

Question 42

once endocytized, the capsid of the poliovirus is ___ and releases __ into the cytoplasm

Answer 42

destabilized; +ssrna

Question 43

what is the capsid shape of the poliovirus?

Answer 43

icosahedral

Question 44

the icosohedral shape of the capsid of poliovirus allows it to survive __

Answer 44

the acidic pH of gut

Question 45

the +ssrna of poliovirus is translated by __ to make a __

Answer 45

host ribosomes; polyprotein

Question 46

viral and host proteases process polyprotein into ___ and __

Answer 46

capsid proteins and machinery for proteases and rna synthesis

Question 47

t/f polyprotein translation if cotranslational

Answer 47

t

Question 48

during polyprotein processing, as soon as viral protease is made, cleavage happens immediately, this is called __

Answer 48

auto proteolysis

Question 49

auto proteolysis in processing poliovirus is due in part to __

Answer 49

viral enzymes acting in cis on the same molecule

Question 50

__ is the viral rna dependent rna polymerase

Answer 50

3D

Question 51

3d uses +ssrna as a template to make __ in the ___ direction

Answer 51

-ssrna; 3'-5'

Question 52

3d makes a __ intermediate

Answer 52

ds rna

Question 53

ds rna is the template for __

Answer 53

+ssrna progeny genome

Question 54

in order to make +ssrna progeny from +rna, the rna polymerase first has to make the __

Answer 54

mirror image

Question 55

what is a disadvantage of having an rna dependent polymerase?

Answer 55

sets off host recognition receptors

Question 56

what is Ribavirin?

Answer 56

an inactive pro-drug which is phosphorylated and activated within cells

Question 57

ribavirin is an analogue for __ and can therefore bind to

Answer 57

adenine and guanine ; cytosine, uracil

Question 58

ribavirin induces ___ viruses, which can be lethal to rna viruses

Answer 58

hypermutation

Question 59

t/f ribavirin can be incorporated into viral rna during genome replication

Answer 59

t