The present invention provides a lentiviral vector system having a higher titer, while sustaining an excellent retrograde transport ability, particularly, in the brain.The present invention also provides a kit for preparing a retrograde transport viral vector comprising:(1) a packaging plasmid containing the gag gene and the pol gene of HIV-1；(2) a packaging plasmid containing an accessory gene of HIV-1；(3) a transfer plasmid containing an target gene (a transgene)； and(4) an envelope plasmid containing, as an envelope gene, a gene encoding a fused polypeptide comprising a fused extracellular domain consisting of the N-terminal region of an extracellular domain of rabies virus glycoprotein (RV-G) and the C-terminal region of an extracellular domain of vesicular stomatitis virus glycoprotein (VSV-G), a transmembrane domain of RV-G or VSV-G, and an intracellular domain of VSV-G, and the like.
