Abstract
Abstract: :
Purpose: To determine whether herpes simplex virus type–1 (HSV–1) entry receptor nectin–1 is expressed in ocular tissues and whether HSV–1 infection has an effect on nectin–1 expression in the eye. Methods:Tissue blocks were sectioned at 6 microns and hydrated to distilled water. Antigen retrieval was performed utilizing DAKO Target Retrieval Solution 10X Concentrate. Sections were exposed to nectin–1 polyclonal antibody (1:50 dilution) for 1 hour at room temperature. Nectin–1 staining was detected with DAKO Envision+ kit, then dehydrated and coverslipped. For HSV–1 detection, tissue sections were deparaffinized with xylene and rehydrated through a series of graded ethanols. HSV–1 antigens were detected using a 1:1000 dilution of a rabbit polyclonal anti–HSV–1 antiserum. Tissue sections were incubated with primary antibody at 43oC for 32 min before the addition of biotinylated anti–rabbit immunoglobulin secondary antibody, avidin–horseradish peroxidase, and 3,3’–diaminobenzidine tetrahydrochloride (0.04%) in 0.05 M Tris–HCL (pH 7.4) and 0.025% H2O2 as a chromogen. Results: In ocular tissues derived from untreated and mock–infected mice, widespread nectin–1 expression was detected among cells of the corneal epithelium, endothelium, conjunctiva, lens epithelium, ciliary body, iris, choroid and retina, but fibroblasts in the corneal stroma and the sclera were negative. Ocular tissues derived from mice euthanized 7 days following corneal HSV–1 inoculation demonstrated HSV–1 protein expression in the corneal epithelium, stroma, endothelium, in the conjunctiva, iris and ciliary body and rarely in the retina. Ocular tissues derived from mice euthanized 7 months following HSV–1 inoculation frequently demonstrated corneal epithelial and stromal inflammation but HSV–1 protein expression was not detected. HSV–1 infection did not lead to a loss of nectin–1 expression in the cell types previously noted as expressing the receptors, but in the inflamed and vascularized stroma, many cells with morphologic features of mononuclear inflammatory cells stained positive for nectin–1. Conclusions: These findings indicate that nectin–1 is widely expressed and is likely to be a mediator of HSV entry into ocular tissue. Corneal stroma does not initially express nectin–1 but after chronic infection shows cells expressing the viral receptor. The other cell types do not alter the level of nectin–1 expression during acute and chronic infection.
Keywords: herpes simplex virus • immunohistochemistry • keratitis