Experimental Teschovirus Encephalomyelitis in Gnotobiotic Pigs

Abstract

A central nervous system (CNS) disorder characterized by non-suppurative encephalomyelitis with neurological signs was induced experimentally in gnotobiotic pigs by intravenous and oral or intranasal inoculation of the porcine teschovirus (PTV) Toyama 2002 strain isolated from breeding pigs in Japan. Lesions consisting of perivascular cuffing of mononuclear cells, focal gliosis, neuronal necrosis and neuronophagia were observed in the brainstem, cerebellum and spinal cord. Non-suppurative ganglionitis in the spinal ganglion and neuritis in the spinal root were also observed. Regardless of the route of inoculation, all pigs infected experimentally with PTV showed a similar distribution of CNS lesions. Histological lesions in the CNS caused by oral or intranasal inoculation of the virus were mild compared with those induced by intravenous infection. Immunohistochemically, the distribution of PTV antigens corresponded closely with the distribution of brain lesions. PTV particles were detected via electron microscopy in the cytoplasm of nerve cells and the endothelial cells of blood vessels in the spinal cord of inoculated pigs. Polymerase chain reaction analysis demonstrated the presence of PTV RNA in the CNS, tonsils and large intestines of 21 of the 22 pigs inoculated. Direct CNS invasion via the blood vessels appears to be a major route of infection for PTV. The gnotobiotic pig provides a useful model for further study of PTV pathogenesis.

Epidemiology and molecular characterization ofPorcine teschovirusin Hunan, China

“…Teschovirus encephalomyelitis (previously known as Teschen/Talfan disease) caused by at least eight serotypes of porcine teschovirus (PTV 1–6, 9 and 10, which are responsible for the milder form of the disease) is considered to be of socio‐economic importance (OIE, ). Many studies on experimentally infected PTV cases have reported non‐suppurative encephalomyelitis with neurological signs (Yamada et al., , , ). However, PTV infections are most often asymptomatic (Knowles, ).…”

“…Since then, the disease spreads throughout Europe and other continents during the 1940s and 1950s, causing devastating economic losses. At present, a mild form of the disease, with the exception of an outbreak in 2009 in the Republic of Haiti, has been described in many countries (Bangari, Pogranichniy, Gillespie, & Stevenson, ; Deng et al., ; Knowles, ; Pinto, Ankers, Werthmann, & Hamilton, ; Salles et al., ; Takahashi, Seimiya, Seki, & Yamada, ; Wang et al., ; Yamada et al., ; Zhang et al., ). The first documented PTV isolate (Swine/CH/IMH/03) in China was identified in 2003, and some cases and epidemiological studies related to PTV in China have been reported since then (Feng et al., ; Lin et al., ; Qiu, Wang, Zhang, Zhang, & Cui, ).…”

Viruses associated with congenital tremor and high lethality in piglets

“…Occasionally, depending on the serotype involved in the infection, PTV clinical manifestations may include enteric, reproductive and respiratory illness. PTV has also been associated with non‐suppurative encephalomyelitis in pigs with severe or mild neurological disorders (Yamada et al., ).…”

“…Porcine teschovirus‐associated encephalomyelitis in pigs was first recorded approximately 88 years ago in the Czech city of Teschen. Subsequently, the Teschen disease spread throughout Europe and other continents, leading to important economic losses to the swine industry (Cano‐Gomez et al., ; Yamada et al., ). Less severe forms of the disease were later recognized in Talfan, Wales and Denmark and were named Talfan disease, poliomyelitis suum or benign enzootic paresis (OIE, ).…”

“…Less severe forms of the disease were later recognized in Talfan, Wales and Denmark and were named Talfan disease, poliomyelitis suum or benign enzootic paresis (OIE, ). Although the PTV‐induced encephalomyelitis is classically caused by strains of PTV serotype 1, other pathogenic PTV strains were also subsequently defined as causative agents of encephalomyelitis (Yamada et al., ).…”