Updated risk assessment of viral pathogens causing swine paralysis

Teschovirus A (TeV-A) and Teschovirus B (TeV-B) from the family Picornaviridae have unsegmented ssRNA genomes of positive polarity. TeV-A is the causative agent of Contagious swine paralysis in domestic and wild boars. The disease was first described in 1929 in Český Těšín (German: Teschen). The virus initially spread in Central and Eastern Europe, but is now found worldwide. TeV-A is primarily ingested orally and initially replicates in the digestive tract before secondary replication of the virus in the central nervous system can occur as part of viremia. TeV-A is excreted by infected animals in the feces over several weeks and has a high Particle stability in the environment.

Based on the symptoms, two forms of the disease are distinguished, which are caused by different strains of TeV-A. Severe forms (triggered by the strain “Teschen” ) are initially characterized by high fever, fatigue, loss of appetite, and ataxia. Later, infected animals develop Diarrhea , central nervous disorders and Paraplegia . The disease is fatal in 20–100% of cases.

In the more common mild forms (e.g. caused by the strain “Talfan”), symptoms such as fever, ataxia and paralysis of the hind limbs also occur; however, the paralysis is usually reversible.

TeV-B was first identified between 2014 and 2017 in endemic studies on the prevalence of TeV-A genotypes in Asian pig farms. To date, TeV-B has been found in the feces and intestinal contents of both healthy domestic and wild pigs and those suffering from diarrheal diseases. However, it has not yet been clarified whether TeV-B is the causative agent of diarrheal diseases. TeV-B is also transmitted fecally or orally. In the Technical Rules for Biological Agents TRBA 462: "Classification of Viruses into Risk Groups," TeV-A is classified in risk group 1 with the index "t2," and TeV-B is not yet classified.

According to Section 5 Paragraph 1 GenTSV in conjunction with the criteria in Annex 1 GenTSV, the ZKBS classifies the Teschovirus B (TeV-B) and strains of the Teschovirus A (TeV-A), which mild form of infectious swine paralysis (e.g. strain “Talfan”) or subclinical forms, as donor and recipient organisms for genetic engineering work in the Risk group 2 The The highly pathogenic TeV-A strain “Teschen” , which causes the severe form of infectious swine paralysis, is Risk group 3 The justification states that TeV-A and TeV-B have a close Host range which includes domestic and wild boars. TeV-B is presumably associated with non-fatal diarrheal diseases. Due to the close relationship between TeV-B and TeV-A, it cannot be ruled out that there is a low risk potential for domestic and wild boars.

The complete updated ZKBS statement can be found at File number 6790-05-02-0063 can be retrieved.