Identification of putative genes involved in parasitism in the anchor worm, Lernaea cyprinacea by de novo transcriptome analysis.

There is little information on the genome sequence of Lernaea cyprinacea a major ectoparasite of freshwater fish throughout the world. We subjected the L. cyprinacea transcriptome (adult and free living stages) to Illumina HiSeq 2000 sequencing. We obtained a total of 31,671,751 (31.67 millions) reads for the adult parasitic stage and 33,840,446 (33.84 millions) for the free living stage. The reads were assembled into 50,792 contigs for the adult stage and 69,378 for the free living stage. Using the pfam database, 41.91% of the transcriptome was annotated. The transcriptome was mined for genes associated with parasitism. To examine gene expression changes associated with the parasitism of L. cyprinacea during the transit from the free living to parasitic stage, we studied the differentially expressed transcripts between the two stages. The microsatellite markers were also identified (9,843 for adult stage; 16,813 for free living stages) and this would facilitate population genetic studies in various geographical isolates of Lernaea. Our data provides the most comprehensive sequence resource available for L. cyprinacea and demonstrates that Illumina sequencing allows de novo transcriptome assembly and gene expression analysis in a species lacking genome information. The data could open new avenues for a wide array of genetic, evolutionary, biological, ecological, epidemiological studies, and a solid foundation for the development of novel interventions against L. cyprinacea.