Fig 6. Virus entry assay in ZB5 cells.

Selected full-length and truncated SHIVs with either Env 375S (wt with serine) or Env 375H (mutated to Histidine) or Env 375Y (mutated to Tyrosine) viruses were tested for their ability to enter cells using ZB5 cells which expresses rhesus CD4 and CCR5 at equal level to human CD4 and CCR5 in TZMbl cells. Cells were seeded at 1 × 10⁴ per well in 96-well plates and incubated 200TCID₅₀ of virus for 5 hrs and virus was removed washed cells and replaced with fresh complete medium. After 48 hrs of post-infection britelite plus reagent was added to measure luciferase activity. As a control cells alone without infection were used to correct for background luciferase activity.