Induction of arginases I and II in cornea during herpes simplex virus infection

Induction of inducible nitric oxide synthase (iNOS) following corneal infec tion with herpes simplex virus type-1 (HSV-1) generates nitric oxide (NO), an important player in the defense against viral infection. Changes in argi nine metabolism during infection are not limited to effects of iNOS but can also involve arginases, which can modulate NO synthesis and produce ornith ine for the generation of polyamines and proline. The latter are important molecules involved in tissue damage and repair during inflammation. In this study we determined the responses of arginase I and II in a murine model o f HSV-l-induced stromal keratitis (HSK). In the cornea iNOS and arginase II mRNA were co-induced as the initial inflammation developed at 2 days posti nfection (p.i.). As stromal keratitis progressed (days 8-15 p.i.) arginase I mRNA was induced tenfold, in contrast to a moderate decrease in arginase II and a loss of iNOS expression. These results suggest that elevated expre ssion of arginase I and II in the cornea at late stages of ocular HSV-I inf ection may play a role in lesion expression in HSK. (C) 2001 Elsevier Scien ce B.V. All rights reserved.