SUSCEPTIBILITY OF HUMAN CORNEAL ENDOTHELIAL CELLS TO HERPES SIMPLEX VIRUS–1

Abstract

Abstract: : Purpose:Of the various potential manifestations of HSV keratitis, corneal endotheliitis (due to lytic infection of the endothelium, in contrast to endothelial involvement in disciform keratitis) is perhaps amongst the least common. One potential explanation for this finding is that corneal endothelial cells may have low intrinsic susceptibility to HSV infection. To explore this possibility, we conducted an in vitro study of the susceptibility of cultured human corneal endothelial cells (HCEC) to HSV–1 infection. We compared the HSV–1 infection susceptibility of HCEC to that of CV–1 cells (a derivative of Vero cells, which are highly permissive to HSV infection and yield high titers of virus). Methods: HCEC, derived by primary culture from corneoscleral rims, were compared with CV–1 cells. CV–1 cells are identical to Vero cells in their permissiveness to HSV infection, but are used in this study for convenience, as they closely approximate HCEC in size. Both HCEC and CV–1 were grown to confluence on bovine extracellular matrix–coated dishes. HSV–1 (McKrae), at a MOI of 5 plaque–forming units (PFU)/cell, was adsorbed onto the cells for 90 min at 37°C. The inocula were then aspirated, the cell monolayers were washed twice with growth medium, and dishes were incubated at 37°C. Cell supernatants were collected at 8, 16, 24, 32, 40, 48 hours post–infection, and viral titers were analyzed by the Tissue Culture Infectious Dose 50 (TCID₅₀) method. Results:The course of HSV–1 infection progressed in a very similar manner in both cell types for the first two time points. However, by 24 hours, titers of HCEC supernatants exhibited viral concentrations several orders of magnitude higher than CV–1 cells (approximately 1x10⁸ and 5x10⁵ PFU/cell, respectively). Our results indicate that HCEC may be even more permissive to viral replication than CV–1 cells. Conclusions:Under the conditions studied, HCEC are highly permissive to HSV infection in vitro. Though further studies must be conducted to test the susceptibility of HCEC to HSV infection in vivo, these data suggest that factors other than intrinsic susceptibility of HCEC to HSV–1 infection may explain the low frequency with which herpetic endotheliitis is observed clinically.

Keywords: herpes simplex virus • cornea: endothelium • extracellular matrix