The authors have developed an objective method for quantitation of herpes simplex virus in the corneal epithelium of rabbits. In vivo confocal microscopy (Confoscan 4; Nidek Technologies, Gamagori, Japan) and corneal esthesiometry (Cochet-Bonnet; Luneau Ophthalmlogie, Chartres, France) of the central cornea were performed bilaterally in all patients and controls. 24 To investigate the effects of NPD1 treatment on SK pathogenesis, groups of animals were treated topically twice daily with the prodrug NPD1 or vehicle starting at 1 day before infection (prophylactic) or day 6 after infection (clinical phase). 3 Similarly, in 8 of the 9 HSK patients, from which intracorneal HSV-specific T cells were recovered, the corneas were devoid of HSV antigens. Twenty three of the 42 virus culture-negative corneal cell cultures tested by PCR were found to contain HSV genetic material. Clinical, histologic, immunologic, and virus detection studies were performed on samples of cornea, draining lymph node (LN), and trigeminal ganglion (TG) cells. Corneal grafts in mice with HSK rejected with higher frequency and more rapid tempo compared with grafts in uninfected mice.
In corneas with HSK and vascularization at the time of grafting, both syngeneic and allogeneic corneal grafts failed with similar frequency and tempo. 1B). In none of the TCLs generated from corneas of any of the HSK patients studied here, reactivity to HSV-1 UL6 or a HuSoCo protein extract could be demonstrated. Importantly, a variably sustained but strongly positive anti-HSV T-cell response was detected in allografted HSK recipients with a similar but lesser response in syngeneic hosts. A previous HSV-1 corneal infection predisposes donor grafts to a high risk of failure by both innate and adaptive immune mechanisms in which an anti-HSV CD4 T-cell response plays a prominent role.