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Non lytic viruses can cause cancers like the HPV. But aren't they reproducing themselves as they don't ruptures the cell. Or are they just not reproduced in enough numbers so that the cell keeps working. But if they stays in the cell and/or not reproducing how are other cells infected to cause a tumor? Just by normal division or within a stem cell?

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You are conflating production of infective viral particles with lysis of the host cell. While true for some well-characterized bacterial viruses, like lambda, or T4, there are other bacterial viruses that can produce infective particles without lysing their host cell (e.g., M13, and related viruses).

Likewise, in mammalian cells there are plenty of examples where either an RNA virus (like the RNA-tumour viruses, also called retroviruses) where the viral genome integrates into the host genome, but can also produce infective viral particles. These viruses have external coats that include both proteins and lipid bilayer membranes (the viruses pinch-off, or bud, from the host cells' surface).

Many DNA viruses also integrate a copy of their genome into the host cells' genome following infection (e.g., Epstein-Barr Virus (it can cause mononucleosis), and members of the Herpes Simplex virus family that infect neurons and can cause chicken pox, or genital herpes). Once you are infected with these DNA viruses your body is never rid of them, rather your immune system and cellular defence mechanisms "fight" the infection such that the titre of infectious viruses drops to nil, but you still have a reservoir of circulating antibodies that can be detected--and used if you are exposed again.

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  • $\begingroup$ Do you think a tumor is growing due to viruses are replicated and leaves the host cell and infects another cell, or is it more likely that that hostcell creates a tumor by dividing himself again and again? $\endgroup$ – Marijn Apr 7 '16 at 13:00
  • $\begingroup$ @Marijn it depends on the tumor, but frequently tumors grow clonally (although there may be multiple "starting" clones), wherein the initially-transformed cell multiplies and makes copies of itself. Remember, cancer is almost never caused by a single event - multiple things need to happen inside a cell for it to become cancerous. See the Knudson hypothesis. $\endgroup$ – MattDMo Apr 7 '16 at 13:57

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