Infection of the adrenal gland as a route to the central nervous system after viraemia with herpes simplex virus in the mouse.

Intravenous inoculation of 4-week-old female NIH (inbred) mice with herpes simplex virus type 1 (HSV-1) strain P2C6 (defective in thymidine kinase) produced bilateral hind limb paralysis in nearly all animals by the 5th day after inoculation; very few mice died. In male mice the incidence and severity of paralysis was considerably lower than in females. The parental strain, CL(101), produced similar paralysis but all mice died by day 7. Observations on paralysis and death after intravenous inoculation are given for other strains of HSV-1 and HSV-2. By day 1 after inoculation of P2C6 significant virus replication had occurred in the adrenal glands but in none of the other organs tested. Titres of virus were similar in the adrenal glands of male and female mice. Histology of the adrenals showed most extensive replication in the cortex with some involvement of the medulla, particularly at the corticomedullary junction. By the 2nd and 3rd days, virus was detected in the lower thoracic spinal cord of both male and female animals but clearance was possibly quicker from males. Adrenalectomy proved that virus reached the cord via the adrenals. In the cord the infection was associated with bilateral demyelination in the ventral white matter as early as day 3.