Efficient transduction of nondividing cells by optimized feline immunodeficiency virus vectors

Second- and third-generation three-plasmid vector systems, termed FELIX, we re constructed from feline immunodeficiency virus (FIV). To enhance vector production, the weak FIV long terminal repeat promoter was replaced with th e human cytomegalovirus enhancer/promoter. To construct a minimal system in which Gag-Pot was the only viral protein present, the cytoplasmic transpor t element was used in place of the FIV Rev-PRE system to facilitate nuclear export of Gag-Pol and the transfer vector. Unconcentrated vector titers ro utinely exceeded 1 x 10(6) IU/mL for most constructs tested. Second- and op timized third-generation vectors were capable of efficiently infecting G(1) /S-and G(2)/M-arrested cells. FIV-based FELIX vectors transduced human dend ritic cells, hepatocytes, and aortic smooth muscle with efficiencies simila r to that of a control 3T3 cell line. All three of these primary cell types were transducible by both the second- and third-generation FELIX vectors, demonstrating that FIV Gag-Pot alone contains the determinants necessary fo r transduction of primary cells. In cross-packaging tests, we observed that HIV Gag-Pol does not substantially package FIV vectors; consequently, use of such vectors in human immunodeficiency virus-infected cells should not l ead to efficient mobilization of the inserted gene. Thus, this FIV-based ve ctor system offers high efficiency and stable delivery of genes to numerous nondividing and primary cell types, opening new avenues for biological inq uiry into normal human cells.