To further determine that WNV-induced cell death is by apoptosis, we conducted TUNEL assay to detect DNA fragmentation, a hallmark of apoptosis. As shown in Figure 1C, very few TUNEL-positive cells were detected in mock-infected cells whereas at day 2 after WNV infection approximately 25% cells were TUNEL positive. Consistent with previously published studies, our **data** provides further support that apoptosis is the main mechanism by which WNV triggers neurotoxicity [9,11,34].