Virus Genomes: Latency

Question 1

in a temperate phage the dormant state in a host cell is called __

Answer 1

lysogen

Question 2

in animal viruses the dormant state in a host cell is called __

Answer 2

latency

Question 3

T/F all viruses can establish latency

Answer 3

false

Question 4

how are latent infections able to go dormant in host cell and maintain longterm persistence in host?

Answer 4

infect and go dormant and be maintained for lifetime of infected cell

Question 5

what is a consequence of latency for host immune response?

Answer 5

a latent virus doesn’t make antigens (protein products), which means antibodies can’t bind and take to immune system

Question 6

what are the 2 stages of achieving latency?

Answer 6

1. integration into host genome

2. longterm retention of viral episome

Question 7

T/F the integration into host genome is reversible

Answer 7

true

Question 8

what are 2 advantages of latency for the virus?

Answer 8

1. viral genome can go through many cycles of division using resources of the host
2. evasion of host immune

Question 9

if protein products are made during latency, they do what 3 things?

Answer 9

1. promote cell proliferation
2. prevent antigen presentation
3. undermine antiviral immune response

Question 10

provide the steps of a bacteriophage infection

Answer 10

1. penetration into host
2. halt host gene expression
3. make viral enzyme and DNA
4. formation of new viral particles
5. host lysis

Question 11

what is a restriction endonuclease?

Answer 11

enzyme that cuts dsDNA at specific nucleotide sequences known as restriction sites

Question 12

how can restriction endonuclease be used as antiviral defence?

Answer 12

it specifically cuts out pieces of foreign DNA

Question 13

how is host DNA protected from restriction endonuclease?

Answer 13

it is methylated by the host enzyme, “methylase”

Question 14

besides preventing viral infection, what are two molecular bio applications for restriction endonucleases?

Answer 14

1. gene cloning

2. forensics

Question 15

what are the 5 steps in isolating a gene of interest?

Answer 15

1. restriction enzyme cuts specific part of dsDNA
2. made into DNA fragment with 2 sticky ends
3. can be joined by base pairing with another fragment cut by the same enzyme
4. joined fragments make circular or linear molecule
5. DNA ligase unites the 2 fragments making a molecule of recombinant DNA

Question 16

T/F eukaryotes have restriction enzymes

Answer 16

false

Question 17

what takes the place of restriction enzymes in eukaryotes>

Answer 17

pattern recognition receptors

Question 18

what sorts of things are recognized by pattern recognition receptors?

Answer 18

viral dsDNA, non-host nucleic acids, 5’ triphosphate RNA