SUMMARY

The originally infected ear of mice latently infected in the cervical ganglia with herpes simplex virus (HSV) was treated with one of five stimuli: stripping with cellophane tape, irradiation with u.v. light, or the application of xylene, dimethyl sulphoxide (DMSO) or retinoic acid. Each of these stimuli induced the appearance of infectious virus in the ganglia 1 to 5 days later, most frequently after 1 to 3 days. Virus was also isolated from the treated ears, most frequently 3 to 5 days after stimulation. In a proportion of mice treated with cellophane tape stripping, xylene, retinoic acid or DMSO, clinical recurrent disease was observed, although in the case of DMSO this proportion was low. Some of the physiological changes induced in the skin by the five stimuli were studied. Treatment with DMSO, cellophane tape stripping or xylene induced almost immediate inflammation in the skin as judged by extravasation of Evans blue dye. Studies with inhibitors suggested that this was mediated by a neurogenic factor together with histamine or 5-hydroxytryptamine, or both of these. In addition, with the exception of mice treated with DMSO, the levels of prostaglandins of the E and F classes in the skin of the ear were elevated 1 to 3 days after treatment. These results are discussed with reference to the mechanisms by which recurrent herpetic disease develops