Cell-to-Cell Transmission Can Overcome Multiple Donor and Target Cell Barriers Imposed on Cell-Free HIV
Figure 3
The reduction in release of cell-free HIVΔvpu by tetherin is overcome in co-cultures.
(A) A barrier was placed into the cell-free path of HIV at the step of virus release by expressing tetherin. (B) HEK293 cells producing HIVLAI-Δvpu and increasing amounts of tetherin (ng) were analyzed for viral gene expression in cells and virus release into the culture supernatant by Western blotting using the α-p24 antibody. The expression of HA-tagged tetherin was confirmed using α-HA antibodies. (C) Relative HIVLAI-Δvpu-GLuc infectivity released by HEK293 producer cells expressing increasing amounts of tetherin (red) or transmitted from producer cells to indicated target cell types in co-cultures. The ratio of infectivity to non-tetherin expressing cells was calculated. (D) Fold of rescue of co-culture over cell-free for the data shown in (C). Fold-rescue was determined by calculating the ratio of the infectivity in co-cultures over the infectivity of cell-free virus at the corresponding tetherin plasmid dose. Error bars represent the standard error of the mean from 3 experiments. The effects of tetherin expression on wild-type HIVLAI are presented in Figure S2.