Distinguishing features

The genus is distinguished on the basis of genetic characters.

Virion

Morphology

No surface morphology is visible by EM.

Physicochemical and physical properties

Virions are stable at acid pH. Buoyant density in CsCl is 1.33 g cm^-3. Empty capsids are often observed in virus preparations.

Nucleic acid

Genome (Zell et al., 2001, Buitrago et al., 2010, Boros et al., 2012b, Yang et al., 2018, Oba et al., 2018): >7,110 nt (5′-proximal sequence missing) (5′-UTR: >335 nt; ORF: 6,600–6,711; 3′-UTR: 67 nt). Teschoviruses have a type IV IRES of about 290 nt which is functional in the absence of eIF-4G. The location of the cre is thought to be within the 2C region. 

Genome organization and replication

Genome layout

VPg+5′-UTR^IRES-IV-[L-1A-1B-1C-1D-2A^npgp/2B-2C/3A-3B-3C-3D]-3′-UTR-poly(A)

The deduced polyprotein varies from 2,199–2,236 aa. The function of the leader polypeptide is unknown. 2A is a short polypeptide with an NPG↓P motif. 

Biology

Clinical manifestations may include a polioencephalomyelitis (“Teschen/Talfan disease”, also known as teschovirus encephalomyelitis), which may vary in severity. The viruses have been associated with a number of disease syndromes, including reproductive and gastrointestinal disorders. Domestic pigs and wild boars are the only known hosts. Natural inter-species recombination has been described. Nineteen genetic types are distinguished by means of phylogenetic analysis (Teschovirus A: teschovirus A1 to -A14, Teschovirus B: teschovirus B1 to -B3; recombinant viruses: teschovirus A15_CP-B_Pol, teschovirus A16_CP-B_Pol).

Antigenicity

Porcine teschoviruses are divided into 13 types (PTV-1 to -13) which are distinct in cross-neutralization tests (where tested).

Derivation of names

Teschovirus: from Teschen disease; named after the Moravian-Silesian town Teschen (now Těšín at the Czech/Polish border.

Species demarcation criteria

Members of a species of the genus Teschovirus:

• are less than 20% divergent in polyprotein aa sequence
• are less than 30% divergent in P1 aa sequence
• are less than 10% divergent in 2C+3CD aa sequence
• share a common genome organization
• share a natural host range

Member species

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.