Isolation of Japanese encephalitis virus from the blood of a cow.

During the summer of 1967, five sentinel cattle were exposed to the bites of vector mosquitoes in the campus of the Fukuoka Prefectural Zootechnical Experiment Station, Ogori-machi, Fukuoka Prefecture. The cattle were bled at an interval of seven days and the blood samples were provided for antibody determination and for virus isolation. The antibody determination was made by means of hemagglutination-inhibition test and the virus isolation by means of intracerebral injection method in suckling mice. Four of the five cattle developed antibody in the period between June 26th and July 17th, but the remainder remained negative of antibody to the last. In one of the four cattles, a strain of virus was successfully isolated from the blood sample obtained on July 10th. One week after the virus isolation the animal developed antibody. The virus isolated was finally identified as Japanese encephalitis virus by means of hemagglutination-inhibition and complement fixation tests.