FIG 9.

Prophylactic treatment of Vero cells with type III IFNs before PIV-3 viral infection. Vero cells were prophylactically treated with recombinant IL-29/-28A/-28B, alone or pooled, at 1 μg/ml for 24 h before TtPIV-1, BPIV-3, or HPIV-3 infection at an MOI of 2 or 0.2 for an additional 24 h. After 48 h, titer plates were used to determine the effect of type III IFNs on virus growth. In the experiment shown in the right panels, IL-29 blocking antibody was added in increasing doses to show specificity of the viral inhibition by type III IFNs. At the highest blocking antibody dose of 80 μg/ml, a log(titer) similar to that of the control was observed. A significant reduction in log(titer) compared to that of the untreated control sample is denoted as follows: *, P < 0.05; #, P < 0.01; +, P < 0.001.