Interactions between the Parasite Philasterides dicentrarchi and the Immune System of the Turbot Scophthalmus maximus. A Transcriptomic Analysis

• Published in: Biology
• Main Authors: Valle, Alejandra, Leiro, José Manuel, Pereiro, Patricia, Figueras, Antonio, Novoa, Beatriz, Dirks, Ron P. H., Lamas, Jesús
• Format: Text
• Language: English
• Published: MDPI 2020
• Subjects: Article; Scophthalmus maximus; Turbot
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7602577/; http://www.ncbi.nlm.nih.gov/pubmed/33076342; https://doi.org/10.3390/biology9100337

SIMPLE SUMMARY: Philasterides dicentrarchi is a free-living ciliate that causes high mortality in marine cultured fish, particularly flatfish, and in fish kept in aquaria. At present, there is still no clear picture of what makes this ciliate a fish pathogen and what makes fish resistant to this ciliate. In the present study, we used transcriptomic techniques to evaluate the interactions between P. dicentrarchi and turbot leucocytes during the early stages of infection. The findings enabled us to identify some parasite genes/proteins that may be involved in virulence and host resistance, some of which may be good candidates for inclusion in fish vaccines. Infected fish responded to infection by generating a very potent inflammatory response, indicating that the fish use all of the protective mechanisms available to prevent entry of the parasite. The findings also provide some valuable insight into how the acute inflammatory response occurs in fish. ABSTRACT: The present study analyses the interactions between Philasterides dicentrarchi (a ciliate parasite that causes high mortalities in cultured flatfish) and the peritoneal cells of the turbot Scophthalmus maximus during an experimental infection. The transcriptomic response was evaluated in the parasites and in the fish peritoneal cells, at 1, 2 and 4 h post-infection (hpi) in turbot injected intraperitoneally (ip) with 10(7) ciliates and at 12 and 48 hpi in turbot injected ip with 10(5) ciliates. Numerous genes were differentially expressed (DE) in P. dicentrarchi, relative to their expression in control ciliates (0 hpi): 407 (369 were up-regulated) at 1 hpi, 769 (415 were up-regulated) at 2 hpi and 507 (119 were up-regulated) at 4 hpi. Gene ontology (GO) analysis of the DE genes showed that the most representative categories of biological processes affected at 1, 2 and 4 hpi were biosynthetic processes, catabolic processes, biogenesis, proteolysis and transmembrane transport. Twelve genes of the ABC transporter family and eight genes of the leishmanolysin ...