Emperor Palpatine representing a virus Emperor Palpatine represents a virus in Immunology Wars, capable of taking over the mind of his enemies and influencing them for his own gain.

Viruses have to infect a host cell in order to survive and replicate. Once inside a cell, the immune system is unable to see the virus. In order to overcome this, cells are able to present fragments of the very thing that is infecting them on their surface via Major Histocompatibility Complex Class I (MHC class I). If a cytotoxic T-lymphocyte recognises the fragments being presented by the infected cell it is able to destroy that cell via the release of chemicals that cause apoptosis, also known as programmed cell death, of the infected cell.

Viruses are sneaky and some have developed ways to stop cells from displaying their fragments on the cell surface, meaning T-lymphocytes cannot identify the infected cells. Fortunately we also have the aptly named natural killer cells (NK cells) which are also able to kill cells that are expressing less MHC class I than normal.

Viruses can also be removed by antibodies before they enter a host cell. Antibodies are able to bind to the viruses neutralising the threat by preventing them from entering cells, marking the viruses for phagocytosis by macrophages and neutrophils, as well as activating the complement system.



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