Figure 3.

Representative images from the olfactory bulb of Balb/c mice infected with VEEV TrD subcutaneously. Uninfected controls (day 0; clinical score 0) exhibit characteristics within normal limits, or minimal to mild 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 (ISH) was used to detect viral RNA, evident by day 3–4 post-challenge (clinical score 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 (morphologically compatible with apoptosis) (*), and the presence of VEEV RNA is most severe/marked by day 5–6 post-challenge.