Tumor-causing viruses oncogene association with

Oncogenes Are Frequently Associated with Tumor-Causing Viruses... 

The term oncogene was coined in association with the search for the tumor-causing principle in retroviruses. Retroviruses contain RNA as the genetic material and can transcribe RNA into DNA with the help of the virus s own enzyme reverse transcriptase. The DNA form of retroviruses can integrate into the DNA of the host cell and, during cell division, is passed on to the daughter cells as a provirus. From the provirus, viral RNA and complete virus particles may be formed. 

There is a complex interplay in the oncogenic virus-host relationship that complicates the study of these viruses as well as the assessment of the risk associated with working with them. Many of the tumor viruses appear to be benign in their natural host, but are oncogenic in a heterologous species. Some viruses may not cause a neoplasm or tumor in their natural host species under normal conditions, but, at times, stress or immuno-... 

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