Distribution and severity of histologic lesions and detection of viral RNA in the brain of DTV-infected mice.

Sagittal brain sections were examined in the rostro-caudal direction. Each mouse was represented by an H&E-stained section as well as a section stained for viral RNA (teal signal) by RNA in situ hybridization. Viral RNA staining score was graded as — (absence of staining), + (very few to low), ++ (moderate), +++ (numerous). Microscopic lesions, including microgliosis (MG), perivascular cuffing (PC), and/or neuronal necrosis (NN), were graded as – (absence of lesions), + (minimal), ++ (mild), +++ (marked). The presence of meningitis, encephalitis, or meningoencephalitis was coded in the last column of the table as M, E, or ME, respectively. NP = region not present on the slide. OB = olfactory bulb, CTX = cerebral cortex, HPF = hippocampal formation, TH = thalamus, HY = hypothalamus, MB = midbrain, P = pons, MY = medulla, CB = cerebellum.