Family: Picornaviridae
Genus: Torchivirus
Distinguishing features
The genus is distinguished on the basis of genetic characters.
Virion
Morphology
No surface morphology is visible by EM (Heuser et al., 2014).
Nucleic acid
Incomplete genome (Farkas et al., 2015): 7,077 nt (5′-UTR: 192 nt; ORF: 6,654 nt; 3′-UTR: 231 nt). The location of the cre has not been identified.
Genome organization and replication
Genome layout:
VPg+5′-UTRIRES-[L-1A-1B-1C-1D-2Anpgp/2B-2C/3A-3B-3C-3D]-3′-UTR-poly(A)
The deduced polyprotein is of 2,218 amino acids. The function of the L protein is unknown. Protein 2A is of 145 amino acids, contains an NPG↓P motif and lacks similarity to other picornaviruses.
Biology
Torchiviruses were isolated from various tortoise species (Testudo graeca, Testudo hermanni, Geochelone sulcata, Pyxis arachnoides) in Hungary and Germany. Viruses were propagated in Terrapene heart permanent cell line (ATCC CCL-50). Torchivirus infections have been associated with various clinical signs and pathological lesions including softening of the carapax of young animals, diphtheroid necrotizing stomatitis and pharyngitis, rhinitis, pneumonia, conjunctivitis, enteritis and ascites, but they have also been isolated from clinically healthy animals (Heuser et al., 2014, Farkas et al., 2015).
Derivation of names
Torchivirus-: from tortoise virus X (chi; Greek letter C).
Species demarcation criteria
There is only a single species in the genus.