The VDL provides pseudotyped lentiviral vectors by changing the plasmid encoding the expression of the envelope protein. This enables changing the host range and tissue tropism of this viral vector. Pseudotypes prepared using VSV-G, LCMV, and RRV envelope proteins make the vector less inflammatory with tropism for the liver (Park, 2003) (Kang et al., 2002), while those prepared using Ebola or Marburg virus coat protein allow transduction of apical surface airway epithelium (Kobinger et al., 2001). Lentivirus vectors pseudotyped with Mokala or Rabies glycoprotein target neuronal cells and neural stem cells (Kang et al., 2002) (Desmaris et al., 2001), while those pseudotyped with RD114 envelope protein transduce primary lympocytes (Sandrin et al., 2002).