Question

What is a reason a virus that spends a long time in the lysogenic cycle could be more dangerous to humans than a virus that does not?

Answer 1

The amount of infected cells.

Explanation:

Viruses, especially bacteriophages (bacterial viruses), have two known reproductive cycles: lytic or lysogenic.

The lytic cycle is when a virus infiltrates a cell and immediately takes over its machinery, producing more viruses in the process. As the new viruses are released, they "destroy" or lyse the cell membrane, hence the name.

The lysogenic cycle happens when a virus infiltrates a cell but rather than quickly hijacking it, the virus inserts its genetic material instead to the host DNA. The problem with this setup is that every time the infected cell undergoes cell division, its daughter cells also contain the viral DNA, and the process goes on. During this stage, the infected cell appears "normal" and will not exhibit symptoms. However, certain triggers like stress can cause the viral DNA to reactivate and begin the lytic cycle.

The danger in the lysogenic stage is that the more time it utilizes, the more infected daughter cells are produced. Should the right trigger be introduced, all these infected cells could potentially release new viruses in far greater numbers as opposed to the lytic cycle, giving the virus a greater chance of infecting more cells.

For more info, you could try visiting these websites:

http://www.brighthub.com/science/genetics/articles/30611.aspx
https://www.boundless.com/biology/textbooks/boundless-biology-textbook/viruses-21/virus-infections-and-hosts-137/the-lytic-and-lysogenic-cycles-of-bacteriophages-553-11763/