Figure 6

UV-inactivated supernatant from WNV-infected human neuroblastoma cell line, SK-N-SH, induce the secretion of pro-inflammatory cytokines from astrocytes. Naïve HBCA cells were either mock-treated or infected with UV-inactivated WNV or WNV at MOI-1 or treated with UV-inactivated supernatant derived from mock- and WNV (MOI-1)-infected SK-N-SH cells, and levels of IL-1β, -6, -8, and TNF-α in treated or infected HBCA culture supernatants were determined by ELISA. Supernatant derived from UV-inactivated mock- and WNV-infected SK-N-SH cells significantly increased the production of pro-inflammatory cytokines within 24 h after treatment. While WNV infection per se increased the production of these cytokines only after 48 h. Furthermore, infection of astrocytes with only UV-inactivated WNV did not induce the expression of aforementioned cytokines at any time point. The data expressed are the mean concentration (pg/ml) ± SD of the amount of IL-1β, -6, -8 or TNF-α, secreted in the supernatant and is representative of three independent experiments. *p < 0.05. **p < 0.001.