Approximately 200 FFU of DENV-2 were allowed to attach to cells for 45 min at 4uC, and then rinsed with cold PBS before peptide was incubated with the target cells for 45 min at 4uC. The cells were rinsed again with cold PBS, and agarose overlays, incubation, and immunological detection were conducted as described for the focus forming unit assay.