DENV-2 strain NG-C was obtained from R. Tesh at the University of Texas at Galveston. Virus was propagated in the Macaca mulatta kidney epithelial cell line, LLC-MK2 (ATCC catalog number CCL-7). Cells were grown in Dulbecco's modified eagle medium (DMEM) with 10% (v/v) fetal bovine serum (FBS), 2 mM Glutamax, 100 U/ml penicillin G, 100 mg/ml streptomycin and 0.25 mg/ml amphotericin B, at 37uC with 5% (v/v) CO 2 .