Fig. 5.

RVFV dependent cell–cell fusion is sensitive to trypsin treatment of the target cells. 293T/17 target cells transfected with pCMVα were treated with trypsin for 15 min at 7 μg/μl (low) or 15 μg/μl (high) to cleave surface proteins. After inhibiting the trypsin with soybean trypsin inhibitor, the target cells were mixed with 293T/17 effector cells transfected with pCMVω and either transfected with VSV-G or NiV glycoprotein constructs or infected with VRP vectors expressing the RVFV glycoproteins or no glycoproteins (empty vector). The cells were treated with buffer at pH 5.2 or 7.4 for 10 min. Cells were then incubated 2.5 h with media at 37 °C pH 7.4, after which β-galactosidase activity was measured. Each experiment was completed in triplicate; each envelope was normalized to 100% at pH 5.2, with VRP empty vector normalized to RVFV fusion at pH 5.2. Bars indicate standard error of the mean.