Lesions in the Centrai Neryous System Eneephalomyocarditis Virus ( EMC - D ) of DBA 12 Mice Infected with the D Variant of

The central nervous system (CNS) ofDBAf2 mice inocutated i.p. with the D variant ofencephalornyocarditis virus (EMC-D) (10' PFUfhead) was examined up to 28 days postinoculation (28 DPI), The virus titer of CNS reached a maximum level at 4 DPI, and infectious viruses became undetectable by 28 DPI. Histopathologically, degeneration of neurons with virus antigens was observed in St. pyramidale hippocaimpi, Nuc. amigdatoideus corticalis and St. granulosum cerebeUi of the brain and in Cornu ventrale of the thoracic to lumbar spinal cord at 6 DPI. In addition, in the spinal cord, demyelination was found in Funiculus ventralis and Funiculus lateralis at 6 DPI and it progressed to form spongiosis at 10 DPI. In eorrespondence with these virological and histopathologicar findings, hind limb paralysis developed in some mice at 6 DPI, and its incldence increased markedly to about 60% at 10 DPI,-KEy woRDs: CNS lesion, DBAf2 rnouse, EMC-D, paralysis. Encephalomyocarditis (EMC) virus was first isolated from non-human primates [7j and then from pigs l13], and it is now considered to be an important causative agent of fetal death f9] and acute necrotizing myocarditis in pigs l1]. Since Yoon et al. [18] established the highly diabetogenic variant of EMC virus (EMC-D) by repeated plaquepurification of the M variant (EMC-M) [4], many studies focused on diabetes have been done in mice using EMC-D [5, 6, 19]. Recently, during the process of investigating diabetic nephropathy in EMC-D-induced diabetic DBA!2NCrj (DBAf2) mice, a highly susceptible strain to EMC virusinduced diabetes, Doi et aL [5] observed hind limb paralysis at a high frequency. In the subsequent preliminary examinations at 3 months postinoculation, we observed uni-phasic or bi-phasic paralysis in DBA12 mice according to the dose of EMC-D inoculated, As the first step of investigating EMC-D-jnduced CNS lesions in mice, this paper describes the virological and histopathological changes in the central nervous system (CNS) of DBA!2 mice. During the subacute stage of infection mice showed uni-phasic hind limb paralysis. The data of mice showing bi-phasic paralysis will be publi$hed else-