Viruses are obligate parasites which depend on living cells to multiply. Their ability to deliver stable RNA and DNA into cells has determined their use in gene therapy. In 1983 Mann et al. developed one of the first retroviral gene therapy vectors for delivery in vitro (Mann, Mulligan et al. 1983). This development was followed by many successfully gene therapy trials of retroviruses (Anderson, Blaese et al. 1990; Levine and Friedmann 1991; Blaese, Culver et al. 1993). Now, retrovirual vectors are implemented in nearly of clinical trials ([June 2010]). Retroviruses belong to the Retroviriade family
