Recovery and identification of West Nile virus from a hawk in winter

West Nile virus was recovered from the brain of a red-tailed hawk that died in Westchester County, N.Y., in February 2000, Multiple foci of glial cell s, lymphocytes, and a few pyknotic nuclei were observed in the brain. Three to 4 days after inoculation of Vero cells with brain homogenates, cytopath ic changes were detected. The presence of West Nile virus antigen in fixed cells or cell lysates was revealed by fluorescent antibody testing or enzym e-linked immunosorbent assay, respectively. Furthermore, Reverse transcript ase-PCR with primers specific for the NS3 gene of West Nile virus resulted in an amplicon of the expected size (470 bp), Electron microscopy of thin s ections of infected Vero cells revealed the presence of viral particles app roximately 40 nm in diameter, within cytoplasmic vesicles. The demonstratio n of infection with the West Nile virus in the dead of the winter, long aft er mosquitoes ceased to be active, is significant in that it testifies to t he survival of the virus in the region beyond mosquito season and suggests another route of transmission: in this case, prey to predator.