Treatment with meliacine, a plant derived antiviral, prevents the development of herpetic stromal keratitis in mice.

Herpetic stromal keratitis is caused by ocular infection with herpes simplex virus type 1 (HSV-1) and constitutes a leading cause of human blindness. The effect of meliacine, an antiviral compound isolated from leaves of Melia azedarach L. that inhibits HSV-1 replication in vitro, was examined on experimental corneal HSV-1 inoculation in Balb/c mice. Mice were inoculated with HSV-1 strain KOS at their corneas after abrasion. Meliacine was administered topically 3 times a day for 4 days beginning 1 day before inoculation. Infected animals treated or not with meliacine were observed carefully for the development of stromal keratitis and the clinical scoring was done 14 days post-infection. Histological examination of corneas and viral isolation from eyes from HSV-1 infected mice treated or not with meliacine were also carried out. It was found that the treatment of HSV-1-induced ocular disease in Balb/c mice with meliacine reduced significantly the development of clinical disease, as well as the histological damage in corneas. The viral titers detected in eyes of infected and treated mice were 2-orders-of-magnitude lower than those corresponding to HSV-1 infected control animals. Mock-infected and treated mice did not reveal any corneal alteration due to the administration of the compound. Meliacine was found to exert a strong antiviral action on HSV-1-induced ocular disease in mice with no evidence of toxic effects.