Hybrid Lentivirus Vectors

Lentivirus vectors are promising tools for gene transfer (1 ,2 ). Retroviral vectors in general offer the unique advantage of stably integrating into the genome of the host cell, thus providing the basis for sustained gene expression. In contrast to the classical oncoretrovirus-derived vectors, lentivirus vectors are highly efficient at infection of nondividing cells. This unique ability is owing to the presence of nuclear localization signals on several virion associated proteins, which include matrix (MA), viral protein R (VPR), and integrase (IN) (3 ) and a cis -acting element termed the central polypurine tract (cPPT) (4 ,5 ).