2.6 Neutralization assays
A pseudotyped EBOV-based neutralization assay was developed to evaluate the neutralizing activity of different samples. Briefly, 50 μL pseudotyped EBOV -containing supernatants were incubated with 50 μL five-fold dilution series of samples at 37 ℃ for 1 h. The pseudotyped EBOV-sample mixtures were then added onto Huh-7 cells seeded in 96-well culture plates at an 80-90% monolayer density. Four hours later, the Huh-7 cells were washed with phosphate-buffered saline (PBS) and incubated for another 48 h. The Huh-7 cells were lysed using 30 μL/well of cell lysis buffer (Promega, WI, USA), and 20 μL lysates were used to determine luciferase activity by adding luciferase substrate (Promega) into the 96-well luminometer plates. Live EBOV was also applied to neutralization assay for comparison with the pseudotyped EBOV-based neutralization assay, which was described previously (Qiu et al., 2014).