Does the immune system destroy virus infected cells?

  1. 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?
     
    Last edited: Jul 28, 2009
  2. jcsd
  3. 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.
     
  4. Monique

    Monique 4,700
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    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.
     
  5. 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?
     
  6. 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.
     
  7. Ygggdrasil

    Ygggdrasil 1,566
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    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).
     
  8. Monique

    Monique 4,700
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    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)
     
  9. Monique

    Monique 4,700
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    If the virus is dormant, it won't be recognized. Most people carry viruses around for life, such as Cytomegalovirus or Epstein-Barr virus.
     
  10. 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?
     
    Last edited: Jul 31, 2009
  11. Monique

    Monique 4,700
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    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:
     
  12. Can NK cells detect virus infected cells without MHC markers. How do they do that?
     
  13. Monique

    Monique 4,700
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    No, they kill any cell that does not have the MHC molecules (since that is a dangerous condition).
     
  14. Thanks Monique for replying every question :smile: Our body is not that bad after all!!
     
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