virology replication

Question 1

what are the basic steps in replication

Answer 1

1. entry
2. replication of genome
3. generation of mRNA to make new viral proteins
4. Assemble new virions
5. Exit
6. spread to new organism

Question 2

what happens in the early phase of replication

Answer 2

adsorption to cell
penetration of cell membrane
uncoating- capside degeneration
-------------
[migration of genome to nucleus (some viruses)]

Question 3

what happens in late stage replication cycle

Answer 3

replication of viral nucleic acid
transcription
translation
assembly
release
spread to new host

Question 4

entry

Answer 4

by adsorption and penetration

Question 5

adsorption

Answer 5

binding to cell and the host range of the virus is often controlled here

the adhesion of atoms, ions, biomolecules or molecules of gas, liquid, or dissolved solids to a surface

Question 6

where does replication occur

Answer 6

in the cytoplasm or the nucleus - location is depending on the virus

Question 7

assembly can occur where?

Answer 7

in nucleus or cytoplasm or the combination of the two

Question 8

release of virions

Answer 8

budding or lysis

Question 9

absorption

Answer 9

incorporation of a substance in one state into another

Question 10

what is the envelope of the cell and where is it from

Answer 10

it is a lipid bilayer

it is derived from the cell

Question 11

what is on the envelope

Answer 11

enveloped glycoprotein this is an envelope protein

appears as spikes

Question 12

the spike of the on the enveloped virus are what?

what are they called

Answer 12

transmembrane glycosylated proteins

envelope glycoproteins (Env)

Question 13

what is the env ectodomain

Answer 13

it mediated the attachment and fusion

it binds to a receptor on the cell surface

Question 14

tropism is determined by?

Answer 14

the receptor on cells to which the env binds

Question 15

the envelope glycoproteins are what

Answer 15

trimers

Question 16

what determines serology

Answer 16

antigenic sites

Question 17

what neutralize viruses

Answer 17

antibodies

Question 18

t/f env can be highly variable

Answer 18

true- it mutates frequently to order to evade adaptive immune responses - mainly antibodies

Question 19

targets for antiviral drugs are developed

by my taking advantage or…

Answer 19

the virus binding and entering

Question 20

viruses that use cell surface receptors to enter the cell

receptors on the cells to which viruses bind are used by the cell for other purposes and exploited by viruses

Answer 20

• influenza A
• HIV-1
• hepatitis C
• rabies
• rhinovirus
• hepatitis B
• Adenovirus type2
• poliovirus

Question 21

how does fusion happen when an enveloped virus enters the cells

Answer 21

fusion can occur

• at the cell surface (like in HIV)[fusion and uncaring]
• or with the membrane of the endosome after it enters the cell. the endosome will release the genome into the cell (influenza virus)[endocytosis , fusion and uncoating]

Question 22

naked virus binding

Answer 22

viral spikes bind to the cell

the trimeric spike proteins mediate binding to their receptor

Question 23

naked virus entry

Answer 23

e.g polivirus

adenovirus(has triads) lysis leads to uncoating

Question 24

viruses must

Answer 24

• replicated their genomes

- make mRNA

Question 25

how do genomes replicated

Answer 25

using either cellular polymerase or a viral polymerase or both

Question 26

replicase

Answer 26

a viral nucleic acid polymerase

Question 27

why is mRNA made by viruses

Answer 27

to generate proteins and new virions

Question 28

what about a virus makes it a good target for drug development?

Answer 28

a virus that uses its own enzyme

Question 29

what happens if a virus uses a cellular enzyme

Answer 29

then probably not a good target for drugs, since enzyme is needed by the cell to do its normal functions
inhibiting a cellular enzyme can be toxic

Question 30

DNA viruses

Answer 30

most replicate in the nucleus
the use the cells machinery

must replicate in proliferating cells that are replicating cellular DNA so that the cell
s DNA replication machinery is active

some induce cell proliferation and can cause cancer.

Question 31

how does an enveloped virus exit from the cells

Answer 31

budding

Question 32

what happens when proteins accumulate to the point of reaching critical concentration

Answer 32

self assemble into viral subunits or higher order structures

Question 33

where does assembly of subunits or virions occur within the cell

Answer 33

nucleus
ER/Golgi
cytoplasm
plasma membrane

Question 34

what are viral proteins first generated as?

Answer 34

poly protein

it is then cleaved into mature proteins by either a viral or a cellular protease

Question 35

what steps are attractive targets for antiviral drug development

Answer 35

assembly and maturation

Question 36

maturation of HIV virion

Answer 36

have a precursor Gag polyprotein

it is immatures when the virion has an uncelaved Gag

mature and infectious after Gag is cleaved

Question 37

how are naked viruses released?

Answer 37

cell lysis