The Liver Fluke Opisthorchis felineus Exosomal tRNA-Derived Small RNAs as Potential Mediators of Host Manipulation.

The role of extracellular vesicle non-coding RNAs in host-parasite interactions remains poorly understood, particularly for human liver flukes. Although tRNA-derived small RNAs (tsRNAs) are emerging as new regulatory molecules in parasite exosomes, they have not yet been characterized for the liver flukes. We performed small RNA sequencing to profile tsRNAs in the exosome-like vesicles derived from the liver fluke Opisthorchis felineus. Transcriptomic data from human cholangiocytes were analyzed to assess the enrichment of the predicted target genes among differentially expressed genes. We identified 247 functional tRNA genes in the O. felineus genome. Exosome-like vesicles were highly enriched for particular tsRNAs: derived from tRNA-Asp-GTC, tRNA-Ile-AAT, tRNA-Lys, tRNA-His, and tRNA-Tyr. This enrichment was independent of both genomic tRNA copy number and the amino acid composition of the trematode proteome. In silico prediction revealed that these tsRNAs target human genes involved in cell cycle, migration, and proliferation. Notably, these predicted target genes were significantly enriched among the differentially expressed genes in treated cholangiocytes. Our study provides the first evidence that O. felineus exosomes carry a specific repertoire of tsRNAs with the potential to regulate host gene networks. We propose that tsRNAs may contribute to host cell manipulation during O. felineus infection.