Figure 5.

Involvement of soluble factors in the antiviral effect mediated by TLR3 in poly I:C-stimulated, MHV-infected macrophages. J774A.1 macrophages were pretreated for 3 h with the conditioned medium (CM) from macrophages prestimulated with TLR ligands for 6 h from Figure 2. CM was diluted 1:1 with the basal medium to replenish nutrients. Then cells were infected with RA59-GFP (1 MOI) for 1 h adsorption and incubated in the basal medium for up to 18 h p.i. Cells pretreated with the CM from mock cells or with fresh basal medium served as negative controls for the TLR-triggered effect. RA59-GFP titers were assessed in cell-free supernatants using a plaque assay on L2 fibroblasts. Error bars represent the standard error of the mean of two replicates (p value relative to cells pretreated with CM from mock, p < 0.01, Student’s t test).