The purpose of the present invention is to provide a lentiviral vector system which sustains a high-frequency retrograde transport ability in animal brain and has an increased titer. The present invention relates to a kit for preparing a retrograde transport viral vector and so on, said kit comprising: (1) a packaging plasmid containing the gag and pol genes of HIV-1; (2) a packaging plasmid containing an accessory gene of HIV-1; (3) a transfer plasmid containing a target gene; and (4) an envelop plasmid containing, as an envelope gene, a gene encoding a fused polypeptide, said fused polypeptide comprising a fused extracellular domain comprising the N-terminal region of the extracellular domain of rabies virus glycoprotein (RV-G) and the C-terminal region of the extracellular domain of vesicular stomatitis virus glycoprotein (VSV-G), the transmembrane domain of RV-G or VSV-G, and the intracellular domain of VSV-G.
NEURON-SPECIFIC RETROGRADE TRANSPORT VECTOR