CIBR has extensive expertise and resources for generation of biosafe lentiviral-based vectors (HIV-1 derived LVs) for gene transfer into the nervous system of experimental animals. LVs are a preferred method for stable and permanent insertion of large transgene sequences (~5-8 kb) into the genome of non-dividing cells, such as neurons in the adult brain and spinal cord. The LV system in use at CIBR has been in use by the Welsh lab for a decade, has been successfully utilized in hundreds of animals, and consists of the so-called 4th generation LV system that has the highest biosafety profile. This system, put into use in collaboration with the Fred Hutchinson Cancer Center, is a 4-plasmid system that generates LVs lacking virulence by the deletion of all viral accessory genes, tat, and env in helper plasmids, and by the segregation of sequences necessary for LV generation (gag-pol and rev) into separate plasmids to greatly reduce recombination probability. The safety profile of the system is further enhanced by the use of a fully heterologous coat-protein (VSV-G) to ensure that experimental LVs are distinct from infectious native virus whose biosafety is further enhanced by inactivation of the viral promoter (deletion of U3 in 3’ LTR) as a second safeguard against replication competence. LV generation and precise stereotaxic injections of microliter volumes of LV solution into the rodent brain occur under electrophysiological guidance within the BSL-2 facilities in CIBR. The CIBR LV production center can generate high-titer LV solutions to induce the expression of a library of fluorescent proteins, RNA inhibitors, and experimental transgenes, under the control of general promoters with known expression efficiencies in brain, or neuron-specific promoters for cell-type targeting. Work by CIBR investigators demonstrated the biosafety of LV transduction for gene transfer into neurons and demonstrated that LV-mediated gene transfer is a valuable approach for examining effects of putative gene-therapy strategies on experimental models of human neurological disorders. LV-gene transfer, especially when combined with in vivo electrophysiology, behavioral analysis, and voltage-clamp assessment of gene transfer effects, as occurs at CIBR, provides a powerful research strategy that is rare among neuroscience research centers.