Family: Chuviridae

Genus: Morsusvirus


Distinguishing features

Morsusviruses are primarily distinguished from viruses of other genera in the family based on nucleic acid sequence and organization differences (Di Paola et al., 2022). Members of the genus Morsusvirus have L protein sequences that are >31% identical to each other.

Genome organization and replication

Morsusviruses have nonsegmented circular genomes of about 10.8 kb with three ORFs encoding a glycoprotein (GP), a large (L) protein with an RNA-directed RNA polymerase (RdRP) domain, and a nucleoprotein (NP) (Li et al., 2015). The replication cycle of morsusviruses remains to be elucidated.


The only classified morsusvirus, Tǎchéng tick virus 4 (TcTV4), has been associated with ixodidan arachnids, i.e., ticks (argasid Argas miniatus Koch, 1844) in China (Li et al., 2015).

Species demarcation criteria

New morsusvirus species should be established when the amino-acid identities of their complete L sequences are <90% compared to other viruses in the genus (Di Paola et al., 2022).