Production of vesicular stomatitis virus G glycoprotein (VSV-G) pseudotyped retroviral vectors

Retrovirus pseudotype is defined as the genome of one retrovirus encapsidated by the envelope protein of a second virus. The host range of the pseudotype is that of the virus donating the envelope protein. Two procedures that use 293GP cells, which are derived from human kidney 293 cells, are described here. The first is based on the high transient transfection efficiency of 293 cells. The retroviral construct and an expression plasmid for VSV-G are co-transfected into 293GP cells that stably express MLV gag and pol proteins. Transiently generated virus is then harvested during consecutive days following DNA transfection. The second procedure involves stable 293GP cell lines containing the VSV-G gene under the control of a promoter whose activity is regulated by tetracycline. Cell lines containing the retroviral vector of interest are established under noninduced conditions. Infectious virus can be harvested following the induction of VSV-G expression in these cell lines.