Figure 2.

Extensive neuronal death is observed only in the brains of Irf2^−/− mice but not in those of WT mice with high viral titers. (A–C) Representative brain images of three SVN-infected mice from three different groups that demonstrate differences in neuronal morphology (A), perivascular cuffing (B), and neuronal cell death by TUNEL staining (C) are shown. Sections of brain from five SVN-infected WT littermate control mice (left; one animal), five moribund Irf2^−/− mice (middle; one animal), and six WT mice with high CNS viral titers (right; one animal) were stained with H&E and examined for neuronal cell death (arrows), neuropil vacuolation (asterisks; A), and perivascular cuffing (arrowheads) by morphology (B). (C) TUNEL staining of slides further confirmed the presence of dead cells (brown; arrows). Bars: (A and C) 50 µm; (B) 100 µm. (D) SINV capsid staining of brain slides from the same mice including those with high CNS viral titers was quantified by ImageJ. A sagittal section of the entire brain near the midline was used for viral antigen staining. The p-value was determined by the unpaired, two-tailed Student’s t test. pos, positive.