Some observations on the tropism of Japanese encephalitis virus in rat brain.

The clinical picture of viral encephalitis is determined by the affinity and persistence of the virus to different brain regions. Therefore, the present study was aimed to investigate the neuropathological changes following Japanese encephalitis virus (JEV) infection in rat at different time points. Twelve days old Wistar rats were infected by intracerebral inoculation of JEV. Presence of JEV antigen was detected in thalamus, striatum, cortex and mid brain on 3, 6, 10 and 20 days post inoculation (d.p.i.). Histopathological changes were also studied in different brain regions at different time points. The highest expression of JEV antigen was found on 6 dpi in all the brain regions studied. JEV antigen was maximum in thalamus on 6 d.p.i. and mid brain on 10 d.p.i. JEV antigen, however, was almost undetectable on 20 d.p.i. in all the regions. The classical pathological changes such as cellular infiltration, perivascular cuffing, meningeal disruption, neuronal damage, neuronal shrinkage, and plaque formation were observed up to 10 d.p.i. The present study reveals high affinity of JEV to thalamus, brainstem and striatum. Rat model of JEV infection may serve as a useful model for studying mechanism of cell injury and recovery in JE.