Herpes simplex infection and experimental allergic encephalomyelitis. An experimental model system for reactivation of EAE.

The effects of herpes simplex virus type 1 (HSV-1) infection on the course of experimental allergic encephalomyelitis (EAE) were studied in rats. Fifty percent of animals given two intracerebral injections of HSV-1, one before and one after induction of EAE, showed clinical and pathologic evidence of recently exacerbated EAE 16 days after the second HSV-1 injection. When HSV-1 injections were administered subcutaneously before and after induction of EAE, 45% of survivors showed pathologic changes of recent EAE. A single injection intracerebally or subcutaneously of HSV-1 given before the development of EAE did not change the clinical severity or time course of EAE. A single injection intracerebrally or subcutaneously of HSV-1 given after the development of EAE did not cause clinical recrudescence of the EAE. Pathologic but not clinical evidence of EAE recurrence was found in three of nine animals given one injection of HSV-1 intracerebrally before and one of control material intracerebrally after induction of EAE. Pathologic evidence of EAE recurrence was found in six of 14 rats given one injection of control material intracerebrally before and one of HSV-1 intracebrally after induction of EAE. Cell suspensions, free of HSV-1, given prior and subsequent to the development of EAE did not cause a change in the EAE severity or a recrudescence of the EAE.