Infection Patterns of Nude Mice to Japanese Encephalitis Virus : Report 3. Virus Recovery from Organs of Nude Mice Inoculated Intracerebrally

1) Each of 92 BALB/c nu/nu and BALB/c nu/+mice was inoculated intracerebrally with JaTH 160 strain of Japanese encephalitis virus (JEV) and the signs of sickness and the death or these animals were pursued for 6 weeks. The development of symptoms and the death of infected nu/nu mice slightly showed the tendency of retardation in comparison with those of nu/+ mice. 2) In the next experiment, each of 25 BALB/c nu/nu and BALB/c nu/+mice was inoculated in the same way, and virus distribution in organs of mice of both groups was examined daily for 5 days. In both of nu/nu and nu/+mice, virus was recognized in brain, blood plasma, cervical lymph nodes and spleen on the 1st day and axillary lymph nodes, inguinal lymph nodes, humeri, femurs and lungs on the 2nd day and brown fat and thymus on the 3rd day after inoculation. Virus in each organ increased in titers rapidly and at the 5th day after inoculation, all of organs of mice were filled with virus. 3) It was in superficial lymph nodes and bone marrows that virus was remarkably recognized at the 1st to the 2nd day after inoculation. 4) In blood plasma of nu/nu mice, virus was seen at the 1st day after inoculation and its titers persisted in the same level from the 1st day to the 5th day. In nu/+ mice, virus titers persisted in the same level as in that of nu/nu mice from the 1st day to the 4th day but at the 5th day, virus in blood plasma was hardly recognized. 5) In nu/nu mice, it was recognized that the time of neutralizing antibody production was slightly later and the rise of antibody was slower and besides, antibody titers were lower with rather large variation than those of nu/+ mice. The above findings suggest that in the intracerebral infection of JEV in mice, spread of virus from inoculated brain to each organ of mice is performed under a certain rule and immunological differences between nu/nu and nu/+ mice are not so striking.