Patent ID: 8652837

Claim:
A lentiviral vector system comprising a lentiviral packaging system and a lentiviral transfer vector comprising a heterologous gene operably linked to a regulatory element, wherein the lentiviral packaging system comprises a structural lentiviral vector system comprising a first lentiviral vector that encodes a structural gene selected from a gag gene, a pol gene or both gag and pol genes, wherein the lentiviral transfer vector comprises a 5′ LTR and a 3′ LTR, wherein the regulatory element is a heterologous regulatory element operable in a mammalian cell, wherein a part or all of a regulatory element of the U3 region of the 5′ LTR is replaced by the heterologous regulatory element, wherein a part of the U3 region of the 3′ LTR is replaced by a heterologous inducible regulatory element that is activated only in the presence of an activator expressed in trans, wherein the replaced part of the U3 region of the 3′ LTR includes sequences that span from nucleotide 418 up to nucleotide 36, wherein the heterologous inducible regulatory element is linked to a part of the 3′ U3 region that comprises a TATA box sequence, wherein the lentivirus is human immunodeficiency virus (HIV), and wherein said lentiviral vector system achieves the titer of vector particles not lower than 1×10 5 TU/ml.