Application of a systemic herpes simplex virus type 1 infection in the rat as a tool for sunscreen photoimmunoprotection studies.

The application of a novel model for sunscreen photoimmunoprotection studies was assessed using a systemic infection of rats with herpes simplex virus type 1 (HSV-1). Rats were irradiated daily with 1 minimal erythemal/oedematous dose of UVB for 7 consecutive days on their shaved backs with or without application of a broad-spectrum sunscreen (containing TiO2) with a sun protection factor of 10. Subsequently, rats were infected intranasally with HSV. UV exposure prior to HSV infection induced increased severity and incidence of clinical signs of disease, suppression of cellular immune responses as assessed by delayed type hypersensitivity and increased viral load in the brain. The sunscreen provided protection against all these UV-induced effects. We conclude that this novel model is a promising way of testing the immunoprotective qualities of sunscreens, based on the response to a common infectious agent of human subjects.