The four main effects of a virus infection on a cell are: cell death, cell fusion forming multinucleated cells, malignant transformation, and no apparent morphologic or functional change.
Here's a more detailed breakdown of each effect:
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Cell Death (Lysis or Apoptosis): This is often due to the virus hijacking the cell's machinery to replicate itself, leading to the inhibition of the cell's normal macromolecular synthesis (DNA, RNA, and protein production). Lysis involves the rupture of the cell membrane, releasing viral particles. Apoptosis, or programmed cell death, can be triggered by the virus or the cell itself as a defense mechanism.
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Cell Fusion (Syncytia Formation): Some viruses can cause infected cells to fuse with neighboring cells, creating large, multinucleated cells called syncytia. This can be mediated by viral surface proteins that promote cell-to-cell fusion. This process allows the virus to spread efficiently, avoiding extracellular immune responses.
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Malignant Transformation: Certain viruses can induce uncontrolled cell growth and division, leading to cancer. These viruses often insert their genetic material into the host cell's DNA, disrupting normal cell cycle regulation and promoting tumor formation. These are typically DNA viruses or retroviruses.
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No Apparent Morphologic or Functional Change (Persistent Infection): In some cases, viral infection may not cause any immediate or obvious changes in the cell's structure or function. The virus may remain latent within the cell or replicate slowly without causing significant damage. This can lead to chronic infections. In these cases, the virus coexists with the host cell.
