Retroviruses: the genetic materials in retroviruses are in the
form of RNA, and have an enzyme called reverse transcriptase
to form viral DNA. After this DNA copy is produced and is
free in the nucleus of the host cell and inserted into the large
DNA molecules in the cell. This process is done by another
enzyme carried in the virus called integrase.18 But can cause
insertional mutagenesis which can be overcome by utilizing
zinc finger nuclease, or beta-globin locus control region