Consequences of viral infection in animal cells

Question 1

Consequences of viral infection in animal cells ?

Answer 1

• transformation into tumor cell
• cell fusion
• Virus multiplication

Question 2

quand il c transforme en tumor cell?

Answer 2

sa veut dire que sa reste permanent

Question 3

what’s cell fusion?

Answer 3

enveloped virus that fuse with the host cell cytoplasmic membrane carries viral proteins that fuse biological membranes

Question 4

the cell fusion results in ?

Answer 4

Hybrid cell that have chromosomal abberration

Question 5

those hybrid cell usually are?

Answer 5

short-lived

Question 6

some viral infection are implicated in the ?

Answer 6

conversion of a normal cell into a tumor cell

Question 7

What’s a tumor cell ?

Answer 7

a cell that has acquired immortllity,characterized by uncontrolled replication

Question 8

How it’s called the cell when it becomes a tumor cell?

Answer 8

process called transformation

Question 9

Which one is known DNA and RNA for causes tumors in animals ?

Answer 9

Both DNA and RNA

Question 10

virus is it the only factor that is involved in tumor cells?

Answer 10

No it’s not, not the only one who causes cancer

Question 11

four different mechanisms in which they become tumor cells?

Answer 11

1-Transduction
2-INsertion of a strong promoteer
3-Inactivation of a tumor suppressor gene
4-Expression of a viral protein that induces transformation (DNA virus)

Question 12

estimated 15-20% of all human cancers aer associated with one of five virus?

Answer 12

• Epstein-Barr Virus(DNA)
• Hepatitis C virus (RNA)
• human T-lymphototrophic virus type 1 (retrovirus)
• Hepatitis B virus (RNA)
• Human Papillomavirus

Question 13

in insertion of a promoter the virus does not encode?

Answer 13

an oncogene

Question 14

where is inserted the strong promoter of the provirus ?

Answer 14

next to a proto-oncogene (c-onc)

Question 15

what happens to the proto-oncogene when the strong promoter is inserted a coter?

Answer 15

the proto-oncogene is then expressed at high levels and results in misregulation of the pathway that prevents transformation

Question 16

The site of integration of the provirus is very____ and transformaion will occur only if a____?

Answer 16

• important

- proto-oncogene is affected

Question 17

insertion of a promoter is usually a?

Answer 17

Retrovirus

Question 18

what’s inactivation of a tumor suppressor gene ?

Answer 18

Insertion of the provirus in a gene involved in the regulation of proto-oncogene
expression

Question 19

what does insertion in inactivation of a tumor suppressor gene causes?

Answer 19

• inactivation of the gene
• uncontrolled expression of the proto-oncogene(C-onc)

(resulting in transformation)

Question 20

expression of a viral protein who can cause that?

Answer 20

DNA virus

Question 21

What can occur in when the DNA virus rentre ds le host?

Answer 21

• Integration of the viral genome into the host genome

- Viral genome may persist in the cell as an extrachromosomal episome

Question 22

when does that DNA virus causes a tumor?

Answer 22

when they infect a nonpermissive host

Question 23

Why does it causes tumor when they infect a nonpermissive host?

Answer 23

• They cannot complete their infection cycle

- cell infected and undergoes uncontrolled replicat

Question 24

Because the virus cannot complete the cycle?

Answer 24

the cell will never die

Question 25

HPV infects what?

Answer 25

epidermal or mucosal epithelial cells that are still able to proliferate (basal layer cells)

Question 26

When HPV infects what do u find in the basal layer?

Answer 26

• viral gene expression is largely suppressed

- limited expression of specific ‘early’ viral genes ( E5,E6 et E7)

Question 27

HPV in the basal layer the cells are still able to ?

Answer 27

proliferate, enhanced proliferation infected cells and their lateral expansion

Question 28

HPV in the midzone layer?

Answer 28

• ‘late’ viral gene expression is initiated

- circular viral genome is then replicated and structural proteins form.

Question 29

HPV, upper layers?

Answer 29

complete viral particles are assembled and released.

Question 30

HPVwhat can happen in some cases ?

Answer 30

viral genome integrates the host genome

Question 31

In HPV, what happen when the viral genome integrates the host genome?

Answer 31

overexpresion of E6 and E7, cell proliferation and formation of a tumor

Question 32

another way of having tumors is ?

Answer 32

Transduction

Question 33

in transduction what does the virus carries?

Answer 33

carries one or many oncogenes,called v-oncogenes

Question 34

what are oncogenes?

Answer 34

tumor-causing genes

Question 35

why v-oncogene?

Answer 35

for virus-encoded oncogene