Approximately 200 FFU of DENV-2 without peptide was allowed to bind and enter target cells for 1 h at 37uC as described for the focus forming unit assay. Unbound virus was then removed by rinsing with PBS and peptide was added to the cells for 1 h at 37uC. Cultures were washed again in PBS and agarose overlays, incubation, and immunological detection was conducted as described for the focus forming unit assay.