Comparative transcriptome analyses of the third and fourth stage larvae of Anisakis simplex (Nematoda: Anisakidae).

We analyzed transcriptome profiles of Anisakis simplex (Nematoda: Anisakidae) 3rd (ASL3) and 4th larvae (ASL4) obtained by RNA-seq, to understand the molecular pathways linked to parasite survival and discover stage-enriched gene expressions. ASL3 were collected from chum salmon and ASL4 were obtained by in vitro culture. Whole transcriptome sequencing was conducted with Illumina sequencer, and de novo assembly was conducted. 47,179 and 41,934 genes were expressed in ASL3 and ASL4 transcriptomes. Of them, 17,633 were known and 29,546 were unmapped sequence for ASL3. 17,126 were known and 24,808 were unmapped sequence for ASL4. Polyubiquitins-related genes and collagen-related genes were the most abundantly expressed in ASL3 and ASL4. Mitochondrial enzyme-related genes were highly expressed both in ASL3 and ASL4. Among the transcripts, 675 were up-regulated in ASL3, while 1015 were up-regulated in ASL4. Several protease-related and protein biosynthesis-related genes were highly expressed in ASL3, all of which are thought to be crucial for invading host tissues. Collagen synthesis-related genes were highly expressed in ASL4, reflecting active biosynthesis of collagens during molting process. This information will extend our understanding of biology of the fish-borne zoonotic parasite A. simplex.