sarcoma virus, were mostly RNA retroviruses. Uniquely, when these viruses infect a cell, they produce a DNA copy of their RNA genome, a provirus, which inserts into the cellular genome and thereafter is replicated along with cellular DNA (see Chapter 1). This remarkable feat not only protects the virus from immune attack and ensures its survival for the lifetime of the cell, but also has the potential to reprogramme the cell’s own gene expression, so influencing its growth control mechanisms.
