A NEW FAMILY OF MURINE RETROVIRAL VECTORS WITH EXTENDED MULTIPLE CLONING SITES FOR GENE INSERTION

Murine retroviral vectors with multiple unique cloning sites in the bo dy and 3' long terminal repeat (LTR) are described. The various altera tions to the vectors include changing the gag+ start codon (AUG) to a stop codon (UAA), a deletion of 468 bp from the envelope region, and a n additional 387-bp deletion of the promoter and enhancer sequences fr om the 3' LTR. Multiple cloning sites in the body and 3' LTR facilitat e double-copy vector construction. The hygromycin resistance and lucif erase genes were subcloned into the body and 3' LTR to evaluate effect s of vector modifications and effects of insert location (body vs. LTR and same orientation vs. reverse orientation with respect to the vect or LTRs) on virus titer. The results indicate the modifications or ins ert position do not negatively influence potential vector titer and ex pression capacity. The described vectors have potentially useful chara cteristics for gene therapy studies.