Does the immune system destroy virus infected cells?

In summary, viruses use MHC markers to evade the immune system and they can lay dormant in a cell before lysing it. NK cells can detect and kill infected cells without displaying MHC markers.
  • #1
sameeralord
662
3
What happens when virus invades a host cell, reproduces and then leaves without destroying the host cell. Then does the immune system destroy these infected host cells? How do viruses do damage. Is it simply by leaving the host cell and destroying it?If bacteria can enter the cell without destroying it why can't it leave the same way?
 
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  • #2
By definition, a virus cannot leave the host cell without destroying it; it kills the cell in a process called lysis, which breaks the cell membrane. Bacterial infection causes lysis as well.
 
  • #3
The immune system can recognize cells that are infected by viruses, once the cell starts to display the virus's proteins on class I MHC molecules on the outside of the cell.
 
  • #4
Monique said:
The immune system can recognize cells that are infected by viruses, once the cell starts to display the virus's proteins on class I MHC molecules on the outside of the cell.

Thanks :smile: However when the virus is engulfed don't the cell engulf the receptor complex that was binded to the virus as well. So how do these receptors remain?
 
  • #5
Just did a research on MHC molecules and understood what you meant :smile: MHC markers basically show to the extracellular environment what proteins are made inside. Thanks Monique for your help :smile: Thanks for kldickson as well but Moniques answer was what I was after.
 
  • #6
It's also worth noting that some viruses integrate their genome into the host cell and lay dormant prior to replicating and lysing the cell (notable examples include retroviruses like herpes simplex and HIV). In these cases, I'm not sure whether the immune system would recognize these infected cells as they would not be actively producing viral proteins in this latent stage (perhaps someone with a better knowledge of immunology can correct me).
 
  • #7
sameeralord said:
Just did a research on MHC molecules and understood what you meant :smile: MHC markers basically show to the extracellular environment what proteins are made inside. Thanks Monique for your help :smile: Thanks for kldickson as well but Moniques answer was what I was after.
You're welcome. What do you think would happen if a virus is so smart to stop class I MHC molecules from reaching the extracellular domain? (in which case the virus's proteins will not be displayed to the immune system, which would be a survival mechanism)
 
  • #8
Ygggdrasil said:
It's also worth noting that some viruses integrate their genome into the host cell and lay dormant prior to replicating and lysing the cell (notable examples include retroviruses like herpes simplex and HIV). In these cases, I'm not sure whether the immune system would recognize these infected cells as they would not be actively producing viral proteins in this latent stage (perhaps someone with a better knowledge of immunology can correct me).
If the virus is dormant, it won't be recognized. Most people carry viruses around for life, such as Cytomegalovirus or Epstein-Barr virus.
 
  • #9
Monique said:
You're welcome. What do you think would happen if a virus is so smart to stop class I MHC molecules from reaching the extracellular domain? (in which case the virus's proteins will not be displayed to the immune system, which would be a survival mechanism)

Jeez! Are their viruses like that? :eek: Then what do we do. Are we gone or can the immune system detect the virus when it on the way to another host cell? So would the host cells keep creating viruses?
 
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  • #10
sameeralord said:
Jeez! Are their viruses like that? :eek: Then what do we do. Are we gone or can the immune system detect the virus when it on the way to another host cell? So would the host cells keep creating viruses?
Yes, there are viruses like that (tumors as well), but our body behaves in a smart way: cells that do not display class I MHC molecules are lysed by the natural killer (NK) cells of our immune system :smile:
 
  • #11
Monique said:
Yes, there are viruses like that (tumors as well), but our body behaves in a smart way: cells that do not display class I MHC molecules are lysed by the natural killer (NK) cells of our immune system :smile:

Can NK cells detect virus infected cells without MHC markers. How do they do that?
 
  • #12
No, they kill any cell that does not have the MHC molecules (since that is a dangerous condition).
 
  • #13
Monique said:
No, they kill any cell that does not have the MHC molecules (since that is a dangerous condition).

Thanks Monique for replying every question :smile: Our body is not that bad after all!
 

1. What is the role of the immune system in fighting off viruses?

The immune system plays a crucial role in protecting the body from viruses. It is responsible for recognizing and eliminating any foreign invaders, including virus-infected cells.

2. How does the immune system identify virus-infected cells?

The immune system uses specialized cells, such as T cells and B cells, to identify virus-infected cells. These cells recognize specific markers on the surface of the infected cells and initiate an immune response.

3. What happens to virus-infected cells once they are identified by the immune system?

Once a virus-infected cell is identified, the immune system will release cytokines, which are chemical messengers that trigger the destruction of the infected cell. This can happen through various mechanisms, such as direct killing by T cells or antibody-mediated destruction by B cells.

4. Can the immune system destroy all virus-infected cells?

The immune system is highly effective at destroying virus-infected cells, but it is not always able to eliminate them completely. Some viruses can evade the immune system and continue to replicate, leading to chronic infections.

5. Can the immune system cause harm to healthy cells while trying to destroy virus-infected cells?

In some cases, the immune system can mistakenly attack healthy cells, leading to autoimmune disorders. However, the immune system has mechanisms in place to prevent this from happening, such as self-tolerance and regulatory T cells.

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