BDV infection induces formation of round 'activated' microglia in mixed cultures. Mixed neuron-glia-microglia cultures were BDV- or mock-infected on the 1st day in vitro (DIV), fixed on the 10th DIV and labeled with microglia-specific markers Iba1, CD11b, ED1 and lectin, or with astrocyte-specific marker GFAP, or a pro-inflammatory cytokine, IL-6. A – Co-localization of CD11b, lectin and Iba1 in round microglia (white arrows) but not in resting CD11b+ microglia (yellow arrows). B – Co-localization of ED1, lectin, and Iba1 in round microglia (white arrows) but not in resting ED1+ microglia (yellow arrows). C – Positive staining for IL-6 in round microglia (white arrows) but not astrocytes. Scale bar – 100 μm. The quantitative analysis of round microglia counts is shown in Figure 2A (the first column).