T-LYMPHOCYTE INFILTRATION IN THE BRAIN FOLLOWING ANTERIOR-CHAMBER INOCULATION OF HSV-1

Following inoculation of the KOS strain of herpes simplex virus type 1 (HSV-1) into one anterior chamber of euthymic BALB/c mice, virus spre ads from the injected eye to the central nervous system and from the c entral nervous system to the optic nerve and retina of only the uninoc ulated eye. In contrast, in athymic BALB/c mice or mice depleted of bo th CD4(+) and CD8(+) T cells, virus spreads to the optic nerve and ret ina of both the injected eye and the uninjected eye. To determine the location in the central nervous system where spread of virus to the op tic nerve and retina of the injected eye is prevented, euthymic BALB/c mice were injected with a mixture of KOS and RH116, a mutant of KOS t hat contains the Escherichia coli beta-galactosidase (beta-gal) gene. Several animals were sacrified each day; serial frozen sections of the brain were prepared and sequential sections were stained for beta-gal or for T cells. At all sites except the suprachiasmatic nuclei, virus and T cells arrived at approximately the same time. However, at day 5 post inoculation (PI), T cells were present in both the ipsilateral a nd the contralateral suprachiasmatic nuclei, but only the ipsilateral suprachiasmatic nucleus was virus-positive. Since virus spreads from t he ipsilateral suprachiasmatic nucleus to the contralateral optic nerv e, these results suggest that T cells infiltrating the area of the con tralateral suprachiasmatic nucleus prior to the al-rival of virus at t his site prevent virus spread into the optic nerve of the inoculated e ye.