A number of tumors from inbred animals such as mice and chickens show associated retroviruses. How do you think they affect gene expression in these animals such that it results in cancer? Propose experiments to test your hypothesis.
There are two ways in which retroviruses can cause tumors. Acute transforming retroviruses have captured proto-oncogenes (genes with the potential to transform cells if expressed in inappropriate ways, such as growth factors) from host cells at some time during their evolution. In the context of the viral genome, these genes act as oncogenes, because they have either (i) acquired mutations during evolution that enhance their activity or make them unsusceptible to normal cellular mechanisms that would limit their activity, or (ii) the genes are next to very strong promoters in the viral genome, so they are expressed at aberrantly ...
This solution gives extensive details regarding the two mechanisms by which retroviruses can cause cancer in animals. It describes the genetic mechanisms involved and how this leads to a loss of growth control that lead to tumor development. The solution also details experiments that can be used to prove these mechanisms.