Retroviral vector with mini-promoter cassette

A recombinant replication competent gammaretrovirus comprising:

• a retroviral GAG protein;
• a retroviral POL protein;
• a retroviral envelope;
• a retroviral polynucleotide comprising Long-Terminal Repeat (LTR) sequences at the 3′ end of the retroviral polynucleotide sequence, a promoter sequence at the 5′ end of the retroviral polynucleotide, said promoter being suitable for expression in a mammalian cell, a gag nucleic acid domain, a pol nucleic acid domain and an env nucleic acid domain;
• a therapeutic cassette comprising at least one mini-promoter cassette having a mini-promoter that is regulated by an RNA polymerase II, wherein the mini-promoter is about 70-500 bp in length and operably linked to a heterologous polynucleotide, wherein the therapeutic cassette is positioned 5′ to the 3′ LTR and 3′ to the env nucleic acid domain encoding the retroviral envelope, and wherein when only one mini-promoter cassette is present the heterologous polynucleotide is 1.2kb to 2.0 kb in length;
• and
• cis-acting sequences necessary for reverse transcription, packaging and integration in a target cell, and wherein the mini-promoter comprises an RSV promoter.