pQCXIN Retroviral Vector is a bicistronic expression vector designed to express a target gene along with the neomycin selection marker (1). Upon transfection into a packaging cell line, this vector can transiently express, or integrate and stably express a viral genomic transcript containing the CMV immediate early promoter, gene of interest, IRES and the neomycin resistance gene (Neor). The gene of interest and the neomycin resistance gene are co-translated, via the internal ribosome entry site (IRES), from a bicistronic message in mammalian cells (2, 3).
This vector incorporates unique features including: optimization to remove promoter interference and self-inactivation. The hybrid 5′ LTR consists of the cytomegalovirus (CMV) type I enhancer and the mouse sarcoma virus (MSV) promoter. This construct drives high levels of transcription in HEK 293-based packaging cell lines due, in part, to the presence of adenoviral E1A (4, 5, 6, 7) in these cells. The self-inactivating feature of the vector is provided by a deletion in the 3′ LTR enhancer region (U3). During reverse transcription of the retroviral RNA, the inactivated 3′ LTR is copied and replaces the 5′ LTR, resulting in inactivation of the 5′ LTR CMV enhancer sequences. This may reduce the phenomenon known as promoter interference (8) and allow more efficient expression.
Also included in the viral genomic transcript are the necessary viral RNA processing elements including the LTRs, packaging signal (Psi+), and tRNA primer binding site. pQCXIN also contains a bacterial origin of replication and?E. coli?Ampr?gene for propagation and selection in bacteria.
pQCXIN is a self-inactivating retroviral vector that is optimized to give high titers, and minimize the possibility of promoter interference. Expresses a gene of interest with the neomycin resistance gene as a bicistronic transcript. pQCXIN is also supplied with the BD Retro-X? Q Vector Set.