It was recognized.t hat the pernasal inoculation of JBE virus established the infection. In the case of pernasal inoculation, JBE virus invaded into the lymph and blood stream to cause general viremia. JBE virus given pernasally was not detected in stool. Virus given pernasal got to the central nerves and caused such histological changes as were noticed when it was inoculated directly into the brain. When CF test was measured on the 23rd day after the inoculation with JBE virus, CF titer showed 8 times.