Nitric oxide and TNF-α quantitation in PIC-infected HMEC-1 supernatants. Supernatants collected from HMEC-1 cells infected at an MOI of 1 were assayed for nitrate/nitrite using Griess reagent (A, columns) as described above. Fold upregulation of the iNOS gene was determined by quantitative RT-PCR (A, line). TNF-α was assayed by ELISA. Each bar represents the mean of 3 independent experiments. * represents p < 0.05 when compared to mock-infected controls.