Which one of the following is used as vector for cloning genes into...

Retroviruses are RNA containing animal viruses that replicate through a DNA intermediate. Retroviruses in animals have the ability to transform normal cells into cancerous cells. A better understanding of the act of delivering genes by pathogen in these eukaryotic hosts has generated knowledge to transform these tools of pathogen into useful vectors for delivering genes of interest of humans. Retroviruses have been disarmed and are now used to deliver desirable genes into animal cells.