1968 Volume 18 Issue 3 Pages 253-260
Japanese B Encephalitis viruses (Furumoto and Nakayama strain) were inoculated into the colostrum-deprived new-born pigs and their clinical symptoms, viremical patterns, virus infective titers in the various organs, localization pattern of the viral antigen and the mode of antibody formation were studied.
1. As clinical symptoms, high fever, anorexia and general malaise were mostly observed. Convulsions and tremors were also observed in the Furumoto-inoculated cases. A transient paresis of the hind legs was observed in some of the Nakayama-inoculated pigs.
2. Viremia occurred in all cases but was most obvious in the case of fresh Furumoto strain and continued for 96 hours.
3. Virological observations revealed the high concentration of infective viruses in the brain, lymph node and lungs, but the date of maximum. concentration was different in each organ.
4. Immunofluorescent technique was adopted to check the localizing pattern of Japanese B Encephalitis viral antigen in the tissues. It reveals that the viral antigen seemed to multiply themselves in the reticuloendothelial cells even on the first day after inoculation, and caused viremia. Some viral antigen was seen in the bronchial epithels, too.
After viremia, a generalized inflammation occurred and the viral antigens were observed in macrophages and large mononuclear cells. In the nervous system, viral antigen appeared temporally in the peripheral nerve sheath of some animals. In the central nervous system the viral antigen generally did not pass through the blood brain barrier, However, in the animals which showed a paresis of hind legs the viral antigen appeared in the ganglion cells of basal nuclei on the same day as the paresis occurred.
5. The infected colostrum-deprived pigs started to produce antibody (hemmagglutination inhibition antibody) on the 4th day after inoculation, when the circulating antigen disappeared rapidly.
The viral antigen in the tissue disappeared on the 7th day when the amounts of circulating antibody came to its maximum.
