Differentially expressed proteins in the skin mucus of Atlantic cod (Gadus morhua) upon natural infection with Vibrio anguillarum

Abstract

BackgroundVibriosis caused by V. anguillarum is a commonly encountered disease in Atlantic cod farms and several studies indicate that the initiation of infection occurs after the attachment of the pathogen to the mucosal surfaces (gut, skin and gills) of fish. Therefore it is necessary to investigate the role of different mucosal components in fish upon V. anguillarum infection. The present study has two parts; in the first part we analyzed the differential expression of skin mucus proteins from Atlantic cod naturally infected with V. anguillarum using two dimensional gel electrophoresis coupled with mass spectrometry. In the second part, a separate bath challenge experiment with V. anguillarum was conducted to assess the mRNA levels of the genes in skin tissue, corresponding to the selected proteins identified in the first part.ResultsComparative proteome analysis of skin mucus of cod upon natural infection with V. anguillarum revealed key immune relevant proteins like calpain small subunit 1, glutathione-S-transferase omega 1, proteasome 26S subunit, 14-kDa apolipoprotein, beta 2-tubulin, cold inducible RNA binding protein, malate dehydrogenase 2 (mitochondrial) and type II keratin that exhibited significant differential expression. Additionally a number of protein spots which showed large variability amongst individual fish were also identified. Some of the proteins identified were mapped to the immunologically relevant JNK (c-Jun N-terminal kinases) signalling pathway that is connected to cellular events associated with pathogenesis. A bath challenge experiment with V. anguillarum showed differential expression of beta 2-tubulin, calpain small subunit 1, cold inducible RNA binding protein, flotillin1, and glutathione S-transferase omega 1 transcripts in the skin tissue of cod during early stages of infection.ConclusionsDifferentially expressed proteins identified in the cod skin mucus point towards their possible involvement in V. anguillarum pathogenesis. The role of some of these proteins in vibriosis in cod described in this paper can be considered unconventional with respect to their established functions in higher vertebrates. Based on the differential expression of these proteins they are possibly important components of fish defence against bacteria and innate immunity at large. The feasibility of utilizing these proteins/genes as markers of bacterial infection or stress in cod needs to be explored further.

Differential proteome profile of skin mucus of gilthead seabream (Sparus aurata) after probiotic intake and/or overcrowding stress

“…In certain agreement with our data, impa gene was up-regulated in European eel and Nile tilapia fish species stressed by seawater change [44]. At proteome level, this protein was identified in skin mucus of Atlantic cod after infection [22], suggesting a role in disease protection on fish.…”

“…It was reported that GST levels increased after exposure to pyrethroids [48]. In addition, GST omega 1 was over-expressed in skin mucus of Atlantic cod after infection [22]. According with these studies, after 30 days of overcrowding stress the oxidative stress by GST over-expression in skin mucus of gilthead seabream could increase.…”

“…Despite of primary role of APOA1 in the reverse cholesterol transport, its presence in the skin mucus and over-expression after probiotic Pdp11 administration suggest not only an extracellular role of antimicrobial activity against pathogens in gilthead seabream, as occurs in striped bass [39], but also an improving of the antimicrobial properties inferred by the Pdp11 probiotic diet. In fact, this protein has been shown to be increased in infected Atlantic salmon and Atlantic cod and showed bactericidal activity [22,34,36,40].…”

Molecular and biochemical tricks of the research trade: -omics approaches in finfish aquaculture

“…Roland et al 2013;Wang et al 2013) or pathogens (e.g. Mu et al 2013;Rajan et al 2013). Indeed, Chinese researchers have applied proteomics technologies to gain a deeper understanding of pathogens and disease in aquaculture; moreover, the use of immunoproteomics was proven successful for the identification of vaccine candidates (see review by Peng 2013).…”

Proliferation and resistance difference of a liver-parasitized myxosporean in two different gynogenetic clones of gibel carp

“…ApoE was found to work as an immune modulator in human (Tenger and Zhou 2003) and to possess antiviral (Dobson et al 2006;Kelly et al 2010), antibacterial (Forbes et al 2013), and antifungal (Rossignol et al 2011) activities. As an orthologous to mammalian apoA-II, apo-14 is a fish-specific fundamental constituent of high-density lipoprotein (Choudhury et al 2009), and is up-regulated in liver of European seabass (Dicentrarchus labrax) infected with Vibrio anguillarum (Sarropoulou et al 2009), in skin mucus of Atlantic cod (Gadus morhua) naturally infected with V. anguillarum (Rajan et al 2013), and in liver and gill of grass carp infected with parasitic copepod Sinergasilus major (Chang et al 2005). In a high-throughput transcriptome analysis of turbot (Scophthalmus maximus) with viral infection stimulus, apo-14 was also revealed to be the second highly expressed gene (Pereiro et al 2012).…”