The Protective Action of Nasally Instilled Immune Serum against Infection with Certain Neurotropic Viruses by Way of the Nose

1. Immune serum instilled intranasally in guinea pigs has protected them from infection with lethal amounts of pseudorabies virus by the nasal route. The same effect was obtained in mice with immune serum against the virus of equine encephalomyelitis (Eastern strain). 2. The protective effect of the immune serum in the nose begins at the time of instillation, is still evident 5 hours later, and usually has disappeared by the end of 24 hours. 3. Attempts to prolong the local effectiveness of immune serum by means of several devices were unsuccessful. 4. The action of the immune serum appears to be a local one in the nose, in view of the fact that the administration of even larger amounts of it intramuscularly failed to protect guinea pigs against infection with pseudorabies by the nasal route.