Herpes simplex virus infections: new concepts in an old disease.

This paper reviews recent clinical and laboratory investigations on herpes simplex viruses (HSV). New findings add to our knowledge about factors influencing HSV infection such as site of infection, virus type and they also point to the importance of the immune system for the outcome of infection. It appears that circumstances at the time of primary infection can modify the type of immune response generated and affect the likelihood of later recrudescence. One of these factors is UV light which seems to act via a photoisomer [cis(Z-)urocanic acid] on the immune system.