Apoptosis and increased expression of Fas ligand after uniocular anterior chamber (AC) inoculation of HSV-1

Abstract

Purpose: To determine if apoptosis occurs in the eyes and brain following uniocular anterior chamber (AC) inoculation of HSV-1 and if expression of Fas ligand (FasL) or Fas is altered by virus infection.

Methods: After inoculation of HSV-1 via the AC route, apoptotic cells in the eyes and brain were identified by TUNEL assay, and TUNEL results indicating DNA fragmentation in the brain were confirmed by DNA laddering assays. Expression of FasL and Fas in the eyes and brain was determined by immunohistochemistry and Western blotting and confirmed by RT-PCR, Southern blotting of RT-PCR products, and sequencing.

Results: After AC inoculation of HSV-1, HSV-1 positive cells and apoptotic cells were observed in the eyes and brain. Immunofluorescent staining revealed that although both FasL and Fas were expressed in the cornea, retinal pigment epithelium cells (RPE), and photoreceptor cells of normal and virus infected mice, Fas and FasL were expressed at different locations in these cells. On day 8 p.i., more FasL DNA expression was observed in HSV-infected mice compared with uninfected mice.

Conclusions: HSV-1 infection following AC inoculation of virus induced apoptosis in the eyes and brain. Although FasL expression was upregulated by HSV-1 infection, these results suggest there are likely to be factors in addition to FasL and Fas, such as Bcl-2 and caspases, that are involved in apoptosis observed in the eyes and brain of HSV-1-infected mice.