Abstract
Prevention of viremia of Japanese encephalitis virus (JEV) in naturally infected swine is one of the most important and necessary measures for the prophylaxis of human JEV infection in Japan, and effective vaccination procedures for animals are expected.
Twenty healthy swine, between 50-80 days of its age, borne in Tokyo were selected and immunized against JEV, by injecting 5ml of Toshiba's purified JEV inactivated vaccine which suspended with equal volume of Dorakeol-6.
Eight weeks after the last immunization, intradarmal virus challenge was made by inoculating 2 or 4ml of 10% emulsion of JaGAr 01 strain infected mice brain (106.5-7.2 LD50 in mice). Detection of viremia was made by the intracerebral inoculation of the blood samples of the immunized swine into a litter of suckling mice.
The results obtained are summarized as follows:
1) Equivocal effectiveness of our adjuvant vaccine was observed when animals were immunized by the single injection method, however, the animals responded to the vaccination by the production of JE HI antibodies greater than 1:10 in their titer were consequently free from viremia when they were challenged by the wild type of JE virus.
2) Duplicated vaccination made on the animals at 7 weeks after the first ones, induced considerable amounts of long, lasting JE HI antibodies, and all the animals did not manifest viremia when they were challenged.
