Fig. 1.

The schematic diagram of acquiring different pseudotyped-viruses based on different packaging systems. (A) HEK 293 T cells were transfected with a plasmid encoding lentiviral backbone and a plasmid expressing envelope protein. The transfected cells produced recombined pseudoviruses and these viral particles could be secreted to extracellular environment before harvesting. (B) HEK 293 T cells were firstly transfected with an envelope protein expression plasmid, twenty-four hours post-transfection, the cells were infected with VSV* ∆G encoding firefly luciferase or GFP. Pseudotyped particles were harvested 20 h post-inoculation. (C) HEK 293 T cells were co-transfected with an envelope protein encoding-plasmid, an MLV Gag-Pol packaging plasmid and the MLV transfer vector encoding a luciferase reporter. The transfected cells produced pseudotyped MLV particles like the HIV systems. Red bar in plasmid represents packaging elements such as gag and pol; green bar in plasmid represents reporter genes, such as GFP and Luciferase; orange bar in plasmid represents envelope protein gene; purple bar in plasmid represents packaging signals, 3’LTR and 5’LTR.