A novel picorna-like virus in the flatworm Stenostomum leucops (Catenulida).

We present the genome sequence and organization and evidence of persistence of a new picorna-like virus infecting the flatworm Stenostomum leucops. The complete genome sequence belongs to a virus with a positive single-stranded RNA genome with two open reading frames (ORFs) flanked by untranslated regions and a polyadenylated C-terminus. The ORFs encode proteins with conserved motifs typical of members of the order Picornavirales. Phylogenetic analysis confirmed membership in this viral order, and it was found to be closely related to viruses found in Biomphalaria (Mollusca) in France and a virus detected in a metagenomic analysis of water sources from the USA, suggesting widespread distribution. RT-PCR analysis revealed that this virus can be detected in a laboratory-grown worm isolate for at least five years, suggesting persistent infection. However, no apparent deleterious effects were observed in the worms in culture, suggesting a possible commensal relationship between the virus and the worms.