Permanent integration of vector DNA: Conventional transfection results in almost entirely transient delivery of DNA into host cells due to the loss of DNA over time. This problem is especially prominent in rapidly dividing cells. In contrast, retroviral transduction can deliver genes permanently into host cells due to integration of the viral vector into the host genome.
Broad tropism: Our packaging system adds the VSV-G envelop protein to the viral surface. This protein has broad tropism. As a result, from commonly used mammalian species such as human, mouse and rat can be transduced. Furthermore, many cell types can be transduced, though our vector has difficulty transducing non-dividing cells (see disadvantages below).
Large cargo space: The wildtype MMLV retroviral genome is ~8 kb. In our vector, the components necessary for viral packaging and transduction occupy ~2.5 kb, which leaves ~5.5 kb to accommodate the user's DNA of interest. Because our vector is designed for the insertion of only an ORF, this cargo space is sufficient for most applications.
High-level expression: The 5' LTR contains a strong ubiquitous promoter that drives high-level expression of the user's gene of interest.
Relative uniformity of gene delivery: Generally, viral transduction can deliver vectors into cells in a relatively uniform manner. In contrast, conventional transfection of plasmid vectors can be highly non-uniform, with some cells receiving a lot of copies while other cells receiving few copies or none.
Effectiveness in vitro and in vivo: While our vector is mostly used for in vitro transduction of cultured cells, it can also be used to transduce cells in live animals.
Safety: The safety of our vector is ensured by partitioning genes required for viral packaging and transduction into several helper plasmids or integrating them into packaging cells. As a result, live virus produced from our vector is replication incompetent.