Abstract
The understanding of gene expression has been greatly enhanced by the ability to transfer cloned genes into cells and to study the mechanism of their regulation. For the past several years it has been recognized that retroviruses are good candidates as vehicles, or vectors, to introduce genes into eucaryotic cells. Retrovirus-derived vectors utilize the biochemical processes unique to this group of viruses, to transfer genes with high efficiency into a wide variety of cell types, in vitro and in vivo. By using retrovirus derived vectors, the effect of newly introduced genes and the mechanism of gene expression can be studied in cell types so far refractory to gene transfer. The special features of this new gene transfer technology have provided for the first time the opportunity of introducing genes into the somatic cells of live animals. Although at present limited to gene transfer into hemopoietic cells, its potential in general studies and applications to human therapy is beginning to be recognized.