The glycoprotein of vesicular stomatitis virus promotes release of virus-like particles from tetherin-positive cells
(A) 293T cells were transfected with plasmids encoding the indicated glycoproteins or mock-transfected. Expression was determined by Western blot analysis using anti-VSV-G antibody (concentrated supernatants from hybridoma CL-2700). Detection of β-actin expression served as loading control. (B) The average of four independent experiments conducted as described for panel (A) and quantified via the ImageJ program is presented. Expression of VSV-G wt was set to 100%. (C) Incorporation of VSV-G wt and mutant LXXXL into VSV pseudotypes was investigated by Western blot analysis using an anti-VSV-G antibody (concentrated supernatants from hybridoma CL-2700). To ensure that similar amounts of pseudotypes were analyzed, levels of particle-associated M proteins were determined using an anti-VSV-M antibody. Pseudotypes harboring no glycoprotein (Mock) served as negative control. The results of a single immunoblot are shown from which irrelevant lanes were cut out. Similar results were obtained in two separate experiments. (D) 293T cells were transduced with equal volumes of the VSV pseudotypes described in panel (C). At 24 h post transduction, luciferase activity in cell lysates was measured. Transduction driven by VSV-G wt was set as 100%. The average of three independent experiments is shown. Error bars indicate SEM. (E) 293T cells were cotransfected with plasmids encoding Gag, the indicated glycoproteins and tetherin. Expression of Gag in supernatants and cell lysates was determined by Western blot. Detection of β-actin expression served as loading control. (F) The average of three independent experiments conducted as described for panel (E) and quantified via the ImageJ program is presented. Error bars indicate standard error of the mean (SEM). Release of Gag from cells coexpressing the highest amount of VSV-G and tetherin was set to 100%. For all graphs (B, D, F), paired two-tailed Students’ t-tests were performed to assess whether differences between VSV-G wt and LXXXL mutant were of statistical significance.