Consequences of viral infection in animal cells Flashcards
Consequences of viral infection in animal cells ?
- transformation into tumor cell
- cell fusion
- Virus multiplication
quand il c transforme en tumor cell?
sa veut dire que sa reste permanent
what’s cell fusion?
enveloped virus that fuse with the host cell cytoplasmic membrane carries viral proteins that fuse biological membranes
the cell fusion results in ?
Hybrid cell that have chromosomal abberration
those hybrid cell usually are?
short-lived
some viral infection are implicated in the ?
conversion of a normal cell into a tumor cell
What’s a tumor cell ?
a cell that has acquired immortllity,characterized by uncontrolled replication
How it’s called the cell when it becomes a tumor cell?
process called transformation
Which one is known DNA and RNA for causes tumors in animals ?
Both DNA and RNA
virus is it the only factor that is involved in tumor cells?
No it’s not, not the only one who causes cancer
four different mechanisms in which they become tumor cells?
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)
estimated 15-20% of all human cancers aer associated with one of five virus?
- Epstein-Barr Virus(DNA)
- Hepatitis C virus (RNA)
- human T-lymphototrophic virus type 1 (retrovirus)
- Hepatitis B virus (RNA)
- Human Papillomavirus
in insertion of a promoter the virus does not encode?
an oncogene
where is inserted the strong promoter of the provirus ?
next to a proto-oncogene (c-onc)
what happens to the proto-oncogene when the strong promoter is inserted a coter?
the proto-oncogene is then expressed at high levels and results in misregulation of the pathway that prevents transformation
The site of integration of the provirus is very____ and transformaion will occur only if a____?
- important
- proto-oncogene is affected
insertion of a promoter is usually a?
Retrovirus
what’s inactivation of a tumor suppressor gene ?
Insertion of the provirus in a gene involved in the regulation of proto-oncogene
expression
what does insertion in inactivation of a tumor suppressor gene causes?
- inactivation of the gene
- uncontrolled expression of the proto-oncogene(C-onc)
(resulting in transformation)
expression of a viral protein who can cause that?
DNA virus
What can occur in when the DNA virus rentre ds le host?
- Integration of the viral genome into the host genome
- Viral genome may persist in the cell as an extrachromosomal episome
when does that DNA virus causes a tumor?
when they infect a nonpermissive host
Why does it causes tumor when they infect a nonpermissive host?
- They cannot complete their infection cycle
- cell infected and undergoes uncontrolled replicat
Because the virus cannot complete the cycle?
the cell will never die
HPV infects what?
epidermal or mucosal epithelial cells that are still able to proliferate (basal layer cells)
When HPV infects what do u find in the basal layer?
- viral gene expression is largely suppressed
- limited expression of specific ‘early’ viral genes ( E5,E6 et E7)
HPV in the basal layer the cells are still able to ?
proliferate, enhanced proliferation infected cells and their lateral expansion
HPV in the midzone layer?
- ‘late’ viral gene expression is initiated
- circular viral genome is then replicated and structural proteins form.
HPV, upper layers?
complete viral particles are assembled and released.
HPVwhat can happen in some cases ?
viral genome integrates the host genome
In HPV, what happen when the viral genome integrates the host genome?
overexpresion of E6 and E7, cell proliferation and formation of a tumor
another way of having tumors is ?
Transduction
in transduction what does the virus carries?
carries one or many oncogenes,called v-oncogenes
what are oncogenes?
tumor-causing genes
why v-oncogene?
for virus-encoded oncogene
