The invention described and claimed in these patent applications provides for novel hybrid vectors which may be used for cell transformation either in vivo, in vitro, or ex vivo. The hybrid vectors, which are capable of integrating into the chromosome of the host cell and are capable of transducing dividing and non-dividing cells, have an adenoviral serotype 5 backbone and two retroviral (Moloney murine leukemia virus) elements upstream and downstream of the transgene. These elements include part of the envelope sequence, the long terminal repeat (LTR) and the packaging signal sequence (upstream), and part of the envelope sequence and LTR (downstream). Due to their hybrid nature, these vectors provide a means of efficient, reliable, long-term gene expression. Furthermore, unlike other chimeric or hybrid vector systems, only a single vector is required to deliver a transgene of interest and retroviral functional proteins are not required. The vectors are packaged and delivered via an adenoviral particle and administered directly to the target cell.