Pathological changes in pigs experimentally infected with porcine teschovirus.

Nonsuppurative encephalomyelitis with neurological signs expressed as flaccid paralysis of the hindlimbs was experimentally induced in three-week-old piglets by a single intravenous injection of the Toyama 2002 strain of porcine teschovirus (PTV) isolated from field pigs in Japan. Lesions characterized by perivascular cuffing of mononuclear cells, focal gliosis, neuronal necrosis and neuronophagia were observed, mainly in the ventral horn of the spinal cord. Nonsuppurative ganglionitis of the spinal ganglion and neuritis of the spinal root were also detected. PTV antigens were detected immunohistochemically and the distribution of these antigens corresponded closely with the distribution of brain lesions. PTV antigens were observed in the ganglion cells before the appearance of the inflammatory changes 3 days post-inoculation (dpi) and were present in the dorsal root and spinal cord on 9 dpi. No lesions of the central nervous system were induced in pigs by oral or intranasal inoculation of this strain of PTV.