Roles of three putative salmon louse (Lepeophtheirus salmonis) prostaglandin E2 synthases in physiology and host\u2013parasite interactions

Christiane Eichner,Sussie Dalvin,Aina-Cathrine Øvergård,Michael Dondrup

doi:10.1186/s13071-021-04690-w

Christiane Eichner, Sussie Dalvin

Open Access

https://doi.org/10.1186/s13071-021-04690-w

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Abstract

BackgroundThe salmon louse (Lepeophtheirus salmonis) is a parasite of salmonid fish. Atlantic salmon (Salmo salar) exhibit only a limited and ineffective immune response when infested with this parasite. Prostaglandins (PGs) have many biological functions in both invertebrates and vertebrates, one of which is the regulation of immune responses. This has led to the suggestion that prostaglandin E2 (PGE2) is important in the salmon louse host–parasite interaction, although studies of a salmon louse prostaglandin E2 synthase (PGES) 2 gene have not enabled conformation of this hypothesis. The aim of the present study was, therefore, to characterize two additional PGES-like genes.MethodsLepeophtheirus salmonis microsomal glutathione S-transferase 1 like (LsMGST1L) and LsPGES3L were investigated by sequencing, phylogenetics, transcript localization and expression studies. Moreover, the function of these putative PGES genes in addition to the previously identified LsPGES2 gene was analyzed in double stranded (ds) RNA-mediated knockdown (KD) salmon louse.Results Analysis of the three putative LsPGES genes showed a rather constitutive transcript level throughout development from nauplius to the adult stages, and in a range of tissues, with the highest levels in the ovaries or gut. DsRNA-mediated KD of these transcripts did not produce any characteristic changes in phenotype, and KD animals displayed a normal reproductive output. The ability of the parasite to infect or modulate the immune response of the host fish was also not affected by KD.ConclusionsSalmon louse prostaglandins may play endogenous roles in the management of reproduction and oxidative stress and may be a product of salmon louse blood digestions.Graphical

Highlights

The salmon louse (Lepeophtheirus salmonis) is a parasite of salmonid fish
prostaglandin E2 synthase (PGES) has been detected in blood cells of crab, indicative of a role in immunity [23], and PGE2 has been detected in both tapeworms and crab nervous tissue where it is likely to be important for development and function [20, 24]
The open reading frame (ORF) translates into a 146-amino acid protein identified as a microsomal glutathione S-transferase 1 like (MGST1) protein holding three transmembrane helixes

Summary

Introduction

The salmon louse (Lepeophtheirus salmonis) is a parasite of salmonid fish. Atlantic salmon (Salmo salar) exhibit only a limited and ineffective immune response when infested with this parasite. Prostaglandins (PGs) have many biological functions in both invertebrates and vertebrates, one of which is the regulation of immune responses. This has led to the suggestion that prostaglandin E2 (PGE2) is important in the salmon louse host–parasite interaction, studies of a salmon louse prostaglandin E2 synthase (PGES) 2 gene have not enabled conformation of this hypothesis. PGES has been detected in blood cells of crab, indicative of a role in immunity [23], and PGE2 has been detected in both tapeworms and crab nervous tissue where it is likely to be important for development and function [20, 24]

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