DETECTION OF VIREMIA OF JAPANESE ENCEPHALITIS IN THE NEW-BORN PIGLET AND SEARCH FOR VIRAL ANTIGEN IN ITS TISSUES BY MEANS OF FLUORESCENT ANTIBODY TECHNIQUE

JE virus was isolated using suckling mice from the blood and other various organs of a new-born piglet, together with still-born fetuses, which were delivered from naturally infected mother sow on 24th of July in 1967. In addition, Fluorescent antibody technique (FAT) was used for detect the viral antigen with in the tissue. The results obtained are as follows:1) JE virus was isolated from the blood, central nervous system (CNS), thymus gland, salivary gland and the lung in the new-born slaughtered within 10 hours after birth. The virus was found to 103.0-3.5 BLU (50% baby mouse lethal unit) of the CNS, 102.3 BLU of thymus and salivary gland, and <101.0 BLU of the lung and the blood. In addition, similar results of the virus isolation were observed in another one of same litter, which died immediately after birth. These data apparantly indicate that pig could be born with viremia following the viral infection in utero.2) The HI antibody titers of the mother sow bled the next day of the delivery were 1:640. The antibody was found to be 2-ME (2-mercaptoethanol)-sensitive and it is assumed that the infection took place several weeks before delivery. Those of the new-born were undetectable (below 1:10).3) The application of FAT was tested for the detection of the viral antigen in various tissues (except salivary gland) of the new-born. The viral antigen was demonstrated only in the nerve cells of the CNS and some kind of cells in the thymus. In the nerve cells, the viral antigen was observed exclusively in cytoplasm of them.