Figure 4

VRP based NT assay using patient serum. Assays were performed in either 24- or 96-well format as indicated. Human serum from a CHIKV patient was serially diluted and preincubated with VRPs corresponding to an MOI of 5, 0.5 or 0.05, respectively. Preincubated samples were used to infect the BHK cells in the 24- or 96-well plates and readout via Gluc secreted into the supernatant was performed at 6 or 24 h post infection as indicated. The bar labeled with VRP represents infection with the appropriate amount of VRPs not preincubated with patient sera. The bar labeled with Mock represents the background measured in untreated (non-infected) BHK cells. Negative (Neg.) serum from a person not infected with CHIKV was used as control. The % infectivity was normalized to VRP infection without serum incubation. Data represent means and standard deviation of experiments performed in triplicate.