HD5 and HD6 negated the activity of HIV entry and fusion inhibitors. HeLa-CD4-CCR5 cells were pre-treated with or without TAK-779 (2 μM) or T-20 (200 nM) for 1 hour. Pseudotyped HIV-1JR-FL virus was incubated with HD5 or HD6 at 20 μg/ml at 37°C for 1 hour. The virus mixture was then added to HeLa-CD4-CCR5 cells in the presence or absence of inhibitors for 2 hours. After washing off unbound virus, infected cells were cultured in the (B) absence (wash off) or (C) presence (add back) of the inhibitors (TAK-779 or T-20) for 48 hours before measurement of luciferase activity. Differences between HIV inhibitor-treated samples vs no inhibitor control in panel A were significant (*p< 0.05). Difference between samples with and without treatment of defensins in panel B was also significant (*p< 0.05). When HIV inhibitors were added back to the cells after viral attachment at 37°C, the difference between samples with and without defensin treatment was not significant (#p > 0.05). Data are means ± SD of triplicate samples and represent three independent experiments.