Fig. 4.

VP40 of marburgviruses, as well as of TAFV, show moderate, noncanonical inhibition of upstream IFN induction. Reporter assays as described in Fig. 2 were conducted to assess relative filovirus VP40 antagonism of the upstream IFN induction pathway, using the same induction reporters. (A) Cells cotransfected with IFNβ reporter vector were induced 1dpt by tenfold increasing amounts of SeV during an experiment identical to that conducted for VP35 in Fig. 2A. (B and C) Cells were induced by a high MOI of SeV (~22.2) for IRF3 or NF-κB reporter assays and harvested at 8 h or 24hpi, respectively. FC = fold change of positive induction relative to uninduced negative control. RLU = relative light units. *=p < 0.05; **=p <0.005; ***=p < 0.0005; ****=p < 0.0001; asterisks above horizontal lines indicate direct comparison of activity values between two antagonists.