Rous Sarcoma Virus (RSV) and Cancer

Retroviruses are a group of single-stranded RNA viruses with the ability to integrate their genome into the host cell DNA.

For example, the Rous sarcoma virus or RSV causes cancer in chickens. Its viral genome contains an oncogene, viral-Src, or v-Src, which is a homolog of the cellular-Src or c-Src. c-Src itself is a proto-oncogene, as it is important for normal vertebrate cell growth.

The v-Src oncogene, when expressed inside the host cell, produces a mutated protein that is hyperactive and leads to abnormal cell growth and cancer progression.

However, the v-Src gene is irrelevant to the survival or replication of the virus. The virus likely acquired it accidentally from another host cell in the past, and the gene subsequently acquired mutations that transformed it into an oncogene.