Fig. 9: Inhibition of VSVΔG/LASVGP infection of human cells.

Flow cytometry analysis was used to determine the neutralizing capacity of the IgG preparations to inhibit LASV GP-mediated infection of human cells. HuH7 cells, differentiated THP-1 cells, and, for comparison, Vero E6 cells were infected with VSVΔG/LASVGP after preincubation of the virus with serially diluted IgG preparations. Infection without sera and untreated cells served as a control. At 22 h post infection, the cells were harvested, fixed, and stained with a polyclonal guinea pig serum against VSV and an anti-guinea pig antibody labeled with FITC as a secondary antibody. a A representative experiment is shown to illustrate flow cytometry-based virus neutralization for Rb#347 and Rb#350 using purified IgG preparations at a dilution of 1:250. For all experiments, living cells were distinguished from cell fragments by FSC-H/SSC-H, referring to cell size and granularity in the starting population. For each cell line, untreated VSVΔG/LASVGP-infected cells were used as positive controls. Uninfected cells treated with the highest concentration of each serum were used as negative controls. These cells were then gated in the serum control that was stained only with the FITC-labeled secondary anti-guinea pig antibody to discriminate between non-infected cells and infected cells (VSVΔG/LASVGP-positive). Percentage of infected cells among the living cells is indicated. b Quantification of infected cells depended on the serum dilution used. Virus control was set to 100% for each cell line, and the relative number of infected cells was calculated for each serum dilution. The values shown represent the mean of two independent experiments.