FIG. 7.

Localization of viral antigen in brain sections. Animals were inoculated intranasally with either wild-type BHV-5, BHV-5gEΔ, or BHV-5gE1 as described in Materials and Methods. The animals were euthanized on days 2, 4, 6, 8, 10, and 12 days postinfection or when they showed neurological signs, and their brains were processed for immunohistochemical analysis as described in Materials and Methods. Representative sections of the olfactory bulb (A), anterior olfactory nucleus (B), and piriform cortex (C) are pictured. In this assay, wild-type BHV-5 spread to the olfactory bulb at 4 to 6 dpi; however, labeling in the bulb was first observed at 8 and 6 dpi for the gE-deleted and gE-exchanged BHV-5, respectively. Wild-type BHV-5 spread to the anterior olfactory nucleus and piriform cortex at 8 dpi. gE-deleted and gE-exchanged BHV-5 took 10 to 12 dpi to spread to these areas. Bar in panel A, 100 μm; bar in panels B and C, 1,000 μm.