Studies on H E R P E T I C Infection in Mice Ii. the Pathways of Invasion of the Central Nervous System after Intranasal Instillation of Virus in Suckling Mice* by Howard

Evidence presented in a previous report (1) showed that a passive immunity is capable of protecting suckling mice against herpes virus instilled intranasally. Because of the wen known neurotropic potentiality of this virus in various host species, it seemed desirable to determine whether the central nervous system (CNS) of suckling mice is invaded by virus entering the organism by the intranasal route, as well as the pathway, or pathways, which might be elected by the virus in such an invasion. At the time this study was undertaken, the literature contained no report of investigations of the pathogenesis of herpetic encephalitis in mice following infection by the intranasal route. While the work was in progress, Burner and Lush (2) reported that herpes virus instilled into the nares of the mouse" . . . . . may reach the central nervous system through the fifth or one of the lower cranial nerves, but the olfactory bulbs are never infected." Using a different method than they, we have been able to confirm their results in part, and also to show that the virus may progress from the nasal mucous membrane to the brain in association with the olfactory nerves. I t is of interest to note that the Australian workers employed the same strain of virus (HF) that we have used in all our experiments, and that both their substrain and ours were maintained by brain-to-brain passage in mice. On the other hand, they used only adult mice in investigating the pathogenesis of intranasal infection.