Gamma-retroviral vectors, commonly designated retroviral vectors, were the first viral vector employed in Gene Therapy clinical trials in 1990 and are still one of the most used. More recently, the interest in lentiviral vectors, derived from complex retroviruses such as the human immunodeficiency virus (HIV), has been growing due to their ability to transduce non-dividing cells (Lewis et al. 1992; Naldini et al. 1996), an attribute that distinguishes them from other viral vectors, including their simple counterparts, gammaretroviral vectors. Retroviral and lentiviral vectors most attractive features as gene transfer tools include the capacity for large genetic payload (up to 9 kb), minimal patient immune response, high transducing efficiency.
