Figure 2

Sustained expression of BG505 SOSIP.664 gp140 by stable cell lines. (A) Intracellular Env expression with continued passage of the 293 T 13# 3–5 and CHO B-D7 stable cell lines (blue curves). The fixed and permeabilized cells were stained with FITC-2G12 (20 μg/ml) after culture for 6 h in the presence of Brefeldin A. MFI values for the Env-expressing clones are recorded in the top right corner of each histogram. Parental cells served as negative controls (red curves show MFI values: ranges 9.12-12.9 for 293 T cells and 7.23-13.2 for CHO cells). (B) Production of BG505 SOSIP.664 gp140 trimers by the stable cell lines throughout the culture period, as determined by ELISA using 2G12 and bio-PGT145. (C) Viability of stable cell clones during passage. The cells were stained with trypan blue, with the percentage of viable cells (parental vs. stable) shown as the passage number increases.