Figure 4.

Representative images from the mid-brain/thalamus of Balb/c mice infected with VEEV TrD subcutaneously. Uninfected controls (day 0; clinical score 0) exhibit characteristics within normal limits, or minimal spongiosis in relation to the gross pathology observed at later time points. Immunohistochemistry stains Iba1 and GFAP were used to detect microglia and astrocytes, respectively, and in situ hybridisation was used to detect VEEV RNA, evident by day 3–4 post-challenge (clinical score 1–2). A substantial increase in both microglia and astrocytes is evident by day 5–6 post-challenge (clinical score 5–7), indicative of infection/trauma. Spongiosis (arrows), neuronal cell death (*), and the presence of VEEV RNA are most severe/marked by days 5–6 post-challenge.