Early adrenal infection by herpes simplex virus type-1 (Miyama + GC strain): special reference to inoculation dose and spread from the adrenal to the central nervous system

Male C3H/HeN mice, aged 5 weeks, were inoculated intraperitoneally (i.p.) with different doses (1 x 10(3), 1 x 10(5), 5 x 10(5), 1 x 10(6) pfu) of the herpes simplex virus type-1 (HSV-1) (Miyama + GC strain). The LD50 of this virus was 10(2) pfu (i.p.) per mouse. All the mice in each group died 12 days after inoculation. Adrenal necrosis was found to be dose-dependent, the threshold dose being 5 x 10(5) pfu. In addition, encephalitis and inflammatory cell infiltration in abdominal ganglia appeared in 3-4 days after inoculation. By the plaque method, HSV-1 was detected first in the adrenal glands, then in neurons in the spinal cord and the brain. These findings suggest that in mice inoculated with doses of virus sufficient to infect the adrenal gland, HSV-1 spreads to the central nervous system through peripheral nerves after replication in the adrenal.