Question

Explain the following: the Rous sarcoma virus induces tumors within days. Most oncogenic retroviruses, however, induce cancer only after a period of months or years. please incorporate bibliografy

Answer 1

Rous sarcoma virus is a retrovirus and is the first oncovirus to have been described. It causes sarcoma in chickens. As with all retrovirus, it reverse transcibes it's RNA genome into cDNA befor integration into the host DNA.

There are two ways viruses can enter the host cell; cell receptor endocytosis or fusion. Endocytosis is the process where virus binds a receptor on the target cell membrane, and the virus is taken into a endocytosed into the cell. Fusion occurs when the virus fuses together with the target cell membrane and releases its genome into the cell. RSV enters the host cell through fusion of the host cell membrane.

Rous sarcoma virus is one of the most rapidly acting carcinogens known, transforming cultured cells in a day or so and causing neoplasia and death in chickens in as little as 2 weeks after infection.

Besides Human Immunodifeciency Virus (HIV), the virus that causes AIDS, there are two other retroviruses that can cause human illness. One is called Human T- lymphotropic virus type 1 (HTLV-1) and the other is called Human T- lymphotropic virus type 2 (HTLV-II).

A virus that is composed not of DNA but of RNA. Retrovirus have an enzyme, called reverse transcriptase, that gives them the unique property of transcribing their RNA into DNA after entering a cell. The retroviral DNA can then integrate into the chormosomal DNA of the host cell, to be expressed there.