De Novo transcriptome assembly of Ligula intestinalis (Linnaeus, 1758) Gmelin, 1790 (Cestoda: Diphyllobothriidae) plerocercoids and their host, the common bream Abramis Brama L. (Cypriniformes: Leuciscidae): model for studying host-parasite interactions.

BACKGROUND: Ligula intestinalisis a parasitic tapeworm with a complex life cycle. During the procercoid stage, they parasitize copepods. Later, the cestodes develop into plerocercoids in the body cavity of plankton-feeding fish before finally maturing within the intestines of piscivorous birds. The impact of plerocercoid infection on hosts may be dramatic, including organ compression, disrupted maturation and reproduction, and alter behavior. These effects, which are mediated by neuroendocrine and immunomodulatory mechanisms, can also lead to a mass fish kill. L. intestinalis and their host fish serve as a major model system for parasitological studies due to the substantial impact of these parasites on the ecology, behavior, and physiology of the fish. However, the molecular mechanisms underlying this host-parasite relationship are not well understood, in part due to limited omics data. Here, we present de novo transcriptome assembly, proteome prediction and functional annotation of the L. intestinalis plerocercoids and various tissues from infected and uninfected breams Abramis brama from Lake Syamozero (Karelia).

METHODS AND RESULTS: A total of three transcriptomes were generated using 132 M paired-end Illumina reads from L. intestinalis plerocercoids, 170 M reads from pooled tissue samples isolated from uninfected bream individuals, and 240 M from infected breams, and were assembled de novo. Additionally, we generated and annotated the predicted proteomes of both species. The transcriptome assemblies were deposited in the NCBI database (BioProject PRJNA1222162), while the translated protein sequences and functional annotations are available in a public repository.

CONCLUSIONS: These data will be valuable for studying molecular adaptations of cestodes to the parasitic lifestyle, as well as host-parasite relationships.