Viruses

Question 1

How do viruses differ in their replication cycle?

Answer 1

Viruses have an eclipse/latent period then burst

Bacteria just linearly replicate from the get go

Question 2

6 stages in viral replication

Answer 2

1. attachment
2. penetration
3. uncoating
4. genome replication, RNA synthesis, protein synthesis
5. assembly
6. RELEASE THE KRAKKEN!

Question 3

Viral attachment to specific receptors on hosts does what?

Answer 3

limited the host species/type of cell

Question 4

2 kinds of receptors for viruses to attach?

Answer 4

protein (ICAM-1 for rhinoviruses)

Carbohydrate (sialic acid for influenza)

Question 5

HIV uses two receptors to attach: explain

Answer 5

on initial CD4

then CCR5 locks it in

Question 6

2 ways to penetrate a cell as a virus:

Answer 6

1. fuse with host cell membrane

2. endocytosis

Question 7

Do fusing with cell membrane viruses have envelopes?

Answer 7

yes

Question 8

Do endocytosis viruses have envelopes?

Answer 8

Yes and they don’t need them either.

Question 9

HIV penetrates how?

Answer 9

Fusion of region gp41

Question 10

What’s an example of a virus that is endocytosed?

Answer 10

togavirus

Question 11

DNA viruses replicate where? exception?

Answer 11

nucleus except for influenza(RNA)

Question 12

RNA viruses replicate where? exception?

Answer 12

cytoplasm except for poxvirus(DNA)

Question 13

What’s vital for viral protein transcription initially?

Answer 13

mRNA

Question 14

What are early viral proteins?

Answer 14

non structural

Question 15

What are late viral proteins?

Answer 15

structural (capsids)

Question 16

How does an RNA virus replicate?

Answer 16

needs RNA dependent DNA polymerase

Question 17

Poliovirus is a plus sense ssRNA, how does it replicate?

Answer 17

goes right to translation to make proteins
auto cleavage of parts
one is a RNA polymerase to make more copies

Question 18

What happens with a -ve sense ssRNA virus?

Answer 18

need to bring your own polymerases (BYOP)

Question 19

Why would a retrovirus want to go back to DNA?

Answer 19

It needs to be DNA to insert itself in the host genome

Question 20

2 viruses that need their own polymerase?

Answer 20

Pox

Hepadna

Question 21

Translation is done how and by whom?

Answer 21

Host cell ribosomes in cytoplasm

Question 22

when do you need virus coded proteases?

Answer 22

post-translational cleavage of viral polyproteins

Question 23

What’s glycosylation in viral replication?

Answer 23

envelope glycoproteins in RER and golgi get deposited on underside of cell surface

Question 24

Why glycosylation?

Answer 24

for budding of enveloped viruses

Question 25

T/F? All non-enveloped viruses are helical?

Answer 25

Nope. Icosahedral

Question 26

Assembly of non-enveloped viruses happen 2 ways:

Answer 26

1. spontaneous assembly

2. proteolytic cleavage to induce assembly

Question 27

Do non-enveloped viruses bud?

Answer 27

Nope.

Question 28

Two viruses that bud?

Answer 28

Flu

Measles

Question 29

Besides budding and lysing out, is there another way viruses can exit the cell?

Answer 29

Elementary Watson. some enveloped viruses use the golgi vesicles’ secretary pathway

Question 30

Example of a virus that uses the secretory pathway?

Answer 30

corona virus

Question 31

4 virus induced changes in cells?

Answer 31

Oncogenic
lytic
chronic
latent

Question 32

What’ s the difference between chronic and latent viral infection?

Answer 32

Chronic is slow release, no cell death

latent is dormant, emerges later as lytic

Question 33

What are cytopathic effects?

Answer 33

changes in virus infected cells you can SEE on light microscope

Question 34

What are inclusion bodies re: viruses

Answer 34

viral proteins visible at site of virus assembly

Question 35

The goal of a virus isn’t to turn a cell cancerous, how does it happen?

Answer 35

The virus oncogenes are growth promoting genes that ‘accidentally’ lead to uncontrolled proliferation of infected cell

Question 36

What kind of inhibition do cancer cells lack?

Answer 36

contact inhibition

Question 37

3 ways viral genetics change?

Answer 37

mutation
recombination (DNA viruses)
reassortment (swapping of segments e.g.. flu/rota)

Question 38

4 ways to halt viruses

Answer 38

1. antibodies
2. kill infected cell via CD8, NK
3. interferon
4. antiviral drugs

Question 39

do antivirals work on classes of viruses?

Answer 39

NOPE. very specific

Question 40

How does acyclovir work?

Answer 40

It’s a nucleoside analog, it mimics guanosine, but missing a key component to extend DNA polymer, so in the infected cell, it uses the analogue and termination occurs cause it can’t replicate