Binding inhibition assays were modified from Thaisomboonsuk, et al [40] .}. Briefly, LLC-MK2 monolayers were rinsed in 4uC DMEM containing 0.8% BSA and 25 mM HEPES, pH 7.5. Virus was incubated at 4uC with peptides, control anti-dengue serum, or heparan sulfate in DMEM/BSA/HEPES for one hour before adding to the monolayers for 2 hours at 4uC. Monolayers were rinsed 3 times with cold DMEM/BSA/HEPES media prior to RNA extraction using the Qiagen RNeasy mini kit (Valencia, CA) per manufacturers instructions. Quantitative, real time, reverse transcriptase polymerase chain reaction (qRT-PCR) was conducted utilizing the Roche Lightcycler RNA Master SYBR Green 1 qRT-PCR kit (Basel, Switzerland), using primers Den_F (TTA-GAGGAGACCCCTCCC) and Den_R (TCTCCTCTAACCT-CTAGTCC) from Chutinimitkul et al [41] .}. and the following cycling conditions: 1 h at 61uC, 30 s at 95uC, followed by 45 cycles of: 5 s at 95uC, 20 s at 61uC, and 30 s at 72uC. Cp values were used to estimate infectious units according to a standard curve. Independent assays were repeated three times, in duplicate or triplicate.