Fig. 6

USUV strains replicate differentially in murine microglia and EU2 strains persist longer. Murine microglia were infected with USUV strains at a MOI of 0.1. a Left panel: Bright light images of control and USUV-infected microglia at 5 dpi. We observe an atypical CPE- in EU2-infected cells. Right panel: Supernatants from infected cells (MOI 0.1) were collected at 2, 5, and 7 dpi, and subjected to TCID50 measurement. Viral production in USUV-infected microglia shows difference in terms of replication and persistence between strains, with greater virulence for EU2. b Left panel: USUV-infected cells were fixed at 2 dpi and labeled with the pan-flavivirus antibody (in red) as showed for EU2 strain. Scale bar = 50 μm. The corresponding quantification is indicated on the right panel (n = 3 independent experiments). c RT-qPCR analysis of TNFα, CXCL10, CCL5, IL6, and IFNβ of mRNA collected at 2 dpi from infected and non-infected (CT) microglial cells. d Analyses of CXCL10 by ELISA in the supernatants of CT- or USUV-infected microglia at 2 dpi. Results are expressed as mean ± SEM. *p < 0.05, **p < 0.01, and ***p < 0.001