VSV-G envelope glycoprotein forms complexes with plasmid DNA and MLV retrovirus-like particles in cell-free conditions and enhances DNA transfection

We have previously shown that vesicles containing the spike glycoprotein of the vesicular stomatitis virus (VSV-G) can associate efficiently with imma ture, non-infectious, envelope-deficient retrovirus-like particles assemble d by packaging cells to produce infectious, pseudotyped viruses in cell-fre e conditions in vitro. We have also previously reported that VSV-G can enha nce DNA lipofection efficiency by interacting with liposomes to form fusoge nic, serum-stable liposomes with enhanced transfection properties. Here, we report that VSV-G can form a complex directly with naked plasmid DNA in th e absence of a lipofection reagent and can thereby enhance the transfection efficiency of the naked plasmid vector. Sucrose gradient sedimentation ana lysis demonstrated that VSV-G can also associate with plasmid DNA and murin e leukemia virus (MLV) gag-pol particles to form ternary complexes that co- sediment with high DNA transfecting activity. The increased transfection ef ficiency with VSV-G was dependent on the presence of the polycation (Polybr ene) in the culture medium during transfection. Enhanced transfection was a bolished by a neutralizing antibody to VSV-G. These results may be useful i n the study of retrovirus assembly, in the further design of hybrid DNA-bas ed retrovirus-like vectors, and in the full in vitro, cell-free assembly of infectious virus-like particles from component parts.