The lethal dose of the peptide- fusion protein that kills 50 percent of the animals (LD50) was evaluated to be more than 50 mg/kg. Then, four groups of the animals (n = 6) were inoculated with 4×103 plaque-forming units (PFU) of the purified DENV2 (DENV2-isolate Malaysia M2, GenBank Toxonomy No.: 11062) and treated with 12.5, 25 and 50 mg/kg of the peptide-fusion protein by intraperitoneal administration; while the forth group was treated with PBS as a mock-administrated group. (A), (B) and (C) The survival percentage of the animals that were administrated with 12.5, 25 and 50 mg/kg of the peptide-fusion protein respectively, compared with the mock-administrated group. Kaplan- Meier analysis was performed to generate survival curves with Prism software 5.01 (GraphPad Software, San Diego, CA).