Biolayer interferometry was performed to examine binding of the peptides to purified, truncated DENV-2 E protein. Amino terminally biotinylated peptides were immobilized onto streptavidin biosensors and then the association and dissociation of truncated E protein with the immobilized peptides was monitored. The interactions of three different concentrations of truncated E protein to peptides DN57opt and 1OAN1 are shown ( Figure 5) . A buffer blank containing no E protein was run for each peptide. The affinities of the peptides for the truncated E protein were calculated with a 1:1 binding model: The dissociation rate constants were: DN57opt k d = 7.7610 24 61.7610 24 s 21 , 1OAN1 k d = 1.6610 23 60.26 10 23 s 21 . We have previously used this system to characterize the binding affinities of several human monoclonal antibodies for DENV E proteins [43] .