Viruses
WNV-NY is strain 3000.0259, isolated in New York in 2000 [42] and passaged twice in C6/36 Aedes albopictus cells to generate an insect cell-derived stock for f.p. inoculations. For i.c. inoculations of WNV-NY, virus strain 3000.0259 was passaged once in Vero cells to generate mammalian cell-derived stock. Attenuated WNV-NS5-E218A was constructed from WNV 3356 strain as described previously [43, 44] and was passaged once in Vero cells, as described previously [45]. Stock titers for all viruses were determined using BHK21 cells for viral plaque assay as previously described [46].