Current development of lentiviral-mediated gene transfer.

Lentiviral-based vectors have been widely used lately in preclinical studies and for the in vitro genetic manipulation of embryonic and adult stem cells. They allow for the transduction of nondividing cells and for stable gene expression. On these grounds, lentiviral vectors look promising for eventual applications for the gene-based treatment of neurological disorders, cardiopathies and inherited or acquired genetic diseases. The best developed and characterized lentiviral vector system is based on the human immunodeficiency virus type 1 (HIV-1). However, safety concerns preclude any possible application of HIV-1-derived vectors in clinical trials. For this reason, gene therapists are currently improving the design of other lentiviral vectors, such as feline immunodeficiency virus, equine anemia infectious virus and Visna virus. These lentiviruses are not pathogenic in humans and are only distantly related to primate Retroviridae. This review summarizes the achievements in improving the design of lentiviral vector systems that are not based on HIV-1.