| Research Abstract |
Swine coronavirus, hemagglutinating encephalomyelitis (HEV), strain 67N, was used to inoculate rats, mice and hamsters by various routes to analyze then viral spread from the peripheral nervous system (PNS) to the central nervous system (CNS). 1) Following intracerebral (i.c.) inoculation, virus-specific antigen was first detected in the pyramidal cells of the hippocampus and cerebral cortex, and later in the large-sized neurons of the pons and spinal cord. Still later immunolabelling was found in Purkinje cells of the cerebellum but not in the ependymal cells, choroid plexus and other glial cells. 2) By direct inoculation into the sciatic nerve or foodpad, the virus was first isolated from the lumber spinal cord and later from the brain. In accordance with these results, antigen-positive neurons were first detected in the lumber spinal cord and later in the cerebral cortex, hippocampus, pons and cerebellum. 3) By intranasal (i.n.) inoculation, HEV antigen was found in the neurons of the main olfactory bulb, anterior olfactory nucleus, septal and dorsal nuclei of the thalamus, ventral brainstem and olfactory cortex. Later limbic area including hippocampus became antigen-positive. The antigen was detected predominantly in neurons but not in glial cells. 4) By direct inoculation into eyeball, antigen-positive neurons were found in retina (RT), dorsal lateral geniculate nucleus (DGL), superior colliculus (SC) and primary visual cortex (VC). Later antigen-positive neurons in RT, DGL, SC and VC increased in number. These results suggest that the virus infects neurons but not in any glial cells and spread via neural pathways from the PNS to the CNS.The virus is useful as transsynaptic tracer for analyzing neuronal connections in the CNS.
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