Fish and shellfish immunology reports最新文献

Autophagy is an evolutionarily conserved process of degradation in eukaryotes, which can form double-membrane vesicles for delivering the trapped cargo to lysosome for degradation, also facilitate host cells against the invasion of foreign pathogens. Recently, autophagy was reported to participate in viral infection in crustaceans. White spot syndrome virus (WSSV) is the most severely viral pathogen for farmed crustaceans, particularly in crayfish and shrimp. In this review, we summarized and discussed the current findings of autophagy involved in WSSV infection in crustaceans, particularly focusing on the identified autophagy-related molecules and their effects on viral infection. We hope this summary will provide us a better understanding of autophagy and its contribution to antiviral immunity in crustaceans.

The coordinated migration of immune cells from lymphoid organs to in or out of the bloodstream, and towards the site of infection or tissue damage is fundamental for an efficient innate and adaptive immune response. Interestingly, an essential part of this movement is mediated by chemoattractant cytokines called chemokines. Although the nature and function of chemokines and their receptors are well documented in mammals, much research is needed to accomplish a similar level of understanding of the role of chemokines in fish immunity. The first chemokine gene identified in teleosts (rainbow trout, Oncorhynchus mykiss) was CK1 in 1998. Since then, the identification of fish chemokine orthologue genes and characterization of their role has been more complex than expected, primarily because of the whole genome duplication processes occurring in fish, and because chemokines evolve faster than other immune genes. Some of the most studied chemokines are CXCL9, CXCL10, CXCL11, and the CXCR3 receptor, all involved in T cell migration and in the induction of the T helper 1 (Th1) immune response. Data from the zebrafish and rainbow trout CXCL9-11/CXCR3 axis suggest that these chemokines and the receptor arose early in evolution and must be present in most teleost fish. However, the pieces of knowledge also indicate that different numbers of gene copies can be present in different species, with distinct regulatory expression mechanisms and probably, also with different roles, as the differential expression in fish tissues suggest. Here, we revised the current knowledge of the CXCL9-11/CXCR3 axis in teleost fishes, identifying the gaps in knowledge, and raising some hypotheses for the role of CXCL9, CXCL10 CXCL11, and CXCR3 receptor axis in fish, which can encourage further studies in the field.

Crustins represent the largest and most diverse family of antimicrobial peptides (AMPs) found in crustaceans. They are classically defined as disulfide-rich peptides/polypeptides holding a typical Whey Acidic Protein (WAP) domain at the C-terminal end. This WAP domain has eight cysteine residues forming a tightly packed structure, the four-disulfide core (4DSC) motif, that is also found in other proteins displaying protease inhibitory properties. Crustins are highly diverse in terms of primary structure, size and biochemical features, thus exhibiting a series of biological functions beyond their antimicrobial properties. In order to better categorize the distinct crustin members, different classification systems have been proposed. In this review, we discuss the current classification systems and explore the biological implication of the impressive molecular diversity of this unique AMP family. We also summarize the recent findings on the role of these effectors in crustacean immunity and homeostasis as well as in host-microbe interactions.

Salmonid alphavirus (SAV) causes pancreas disease (PD) in Atlantic salmon (Salmo salar). In seawater-farmed salmonids in the southern part of Norway SAV subtype 3 (SAV3) is dominating. PD continues to cause significant economic and fish health concerns in this region despite years of extensive use of oil-adjuvanted vaccines (OAVs) containing inactivated whole virus (IWV) antigens. In the current study, three commercially available PD vaccines were tested. Group A got a DNA vaccine (DNAV) injected intramuscularly (i.m.) plus an OAV without a PD component injected intraperitoneally (i.p.). Groups B and C got different OAV IWV vaccines injected i.p., respectively. The control group was i.p. injected with saline. Approximately 12 weeks after vaccination, the post smolt groups were challenged in seawater with SAV3 by cohabitation. Samples were collected pre-challenge, and at 19, 54 and 83 days post-challenge (dpc). There were no differences in growth or visible intraperitoneal side effects between the immunized groups prior to challenge. Fish in group A had significantly higher SAV3 neutralizing antibody titers than the other groups pre-challenge and significantly lower SAV3 viremia levels than the control group at 19 dpc. Fish in group A had significantly more weight gain than the other groups measured at 54 and 83 dpc. Prevalence and severity of heart necrosis at 19 dpc and loss of exocrine pancreas tissue at 54 and 83 dpc were significantly lower in groups A and B compared to group C and controls. The cumulative mortality in the control group during the challenge period was 10.5%. Group A experienced the lowest mortality (6.4%) albeit not statistically different from the controls. The results suggest that DNAV may reduce the clinical and economic impact of PD by improved protection against SAV3-induced changes in pancreas tissue and growth impairment.

Avicennia marina mangrove leaves polysaccharide (AMLP) was used for the synthesis of polysaccharide-based selenium (AMLP-SeNPs) and silver nanoparticles (AMLP-AgNPs). The synthesized nanoparticles were further characterized by UV-Vis, DLS, FT-IR, X-ray diffraction, and HR-TEM analysis. A 60-day (8 weeks) feeding trial experiment was conducted to investigate the effects of AMLP, AMLP-SeNPs, and AMLP-AgNPs dietary supplementation on growth performance parameters, blood parameters, immunological and enzymatic profiles in Cyprinus carpio. The characterization results of AMLP-SeNPs and AMLP-AgNPs confirmed the formation of well-stabilized spherical nanoparticles with a mean particle size of 37.25 and 72.40 nm, respectively having a crystalline structure. The feeding experiment results demonstrated that 2 mg/kg of AMLP-SeNPs followed by 0.2 mg/kg of AMLP-AgNPs showed significantly (p ˂ 0.05) higher final weight, weight gain (WG), specific growth rate (SGR%), protein and lipid efficiency, and lower food conversion ratio as compared to other groups. The catalase, superoxidase dismutase, and glutathione peroxidase activity were significantly (p ˂ 0.05) higher in the group fed 2 mg/kg supplemented AMLP-SeNPs. Total protein and globulin contents were significantly (p ˂ 0.05) higher and albumin concentration was significantly lower in fish that received 2 mg/kg of AMLP- SeNPs as compared to control. A significant increase in serum HDL and decrease in LDL and MDA concentrations were observed in the group supplemented with 2 mg/kg of nano selenium. The body's crude lipid, protein, moisture, and ash were not significantly different from the control. The AMLP-SeNPs showed significantly (p ˂ 0.05) lower aspartate aminotransferase (AST), alanine aminotransferase (ALT), and higher alkaline phosphatase (ALP) activities compared to other test groups. The relative percentage survivability (RPS%) was higher in AMLP-SeNPs (84.6%) followed by AMLP-AgNPs (76.7%) after 8^th weeks of supplementary diets as compared to control groups. Overall, the finding of these studies revealed that the inclusion of AMLP-SeNPs improved the growth performance and antioxidant defense system, enhance immune response, and provide resistance against Aeromonas hydrophila in Common carp.

The current study was designed to characterize immune genes and compare their expression during ontogenetic developmental stages in progenies of wild-collected and captive-matured T. putitora. The full-length cDNA sequences of Tptlr2, Tpmyd88, Tpcd36, and Tpil8 were 2814, 1545, 1807, and 653 bp in length, with ORFs of 2379 bp, 855 bp, 1410 bp, and 297 bp, encoding for putative peptides of 793, 284, 469 and 98 amino acids, respectively. The predicted peptide sequences of the genes had high sequence homology and structural conservation with other teleost fishes, especially cyprinids. The expression of Tptlr2 was relatively low in both wild- and captive-bred offsprings during the early embryonic stages, but significantly increased later in development. The mRNA abundance of the Tpmyd88 gene was significantly low until the blastula stage, then increased notably from the gastrula stage to the advanced fry stage. The Tpcd36 expression elevated during later developmental stages, peaking at advanced fry stage in both. On the other hand, expression of Tpil8 was relatively low until the blastula stage and showed a moderate increase from the organogenesis stage onwards in wild-bred offsprings, whereas a significant upregulation was seen in the captive-bred offsprings from the organogenesis stage until the advanced fry stage, with its maximum expression at the pre-metamorphosis stage. Overall, the findings suggest the crucial role of Tpmyd88, Tptlr2, Tpcd36, and Tpil8 in inducing innate immunity in embryonic and larval stages of T. putitora. Further, the considerably higher expression of the immune genes in the embryonic and larval stages of captive-bred offsprings may indicate a stronger immune system.

Crab species are economically important crustaceans with high demand in markets. Development of the culture system resulted in an increase in disease outbreaks. Disquisition and application of methods that can prevent and control diseases during the crab culture period are crucially essential. The application of prebiotics and probiotics to replace the overuse of antibiotics has practical significance in sustainability of the crab farming. Previously, both prebiotics and probiotics have shown to confer benefits in growth promotion, immunostimulation, and disease control in crab culture. These components can directly stimulate humoral immunity by increasing activities of lysozyme, phagocytosis, respiratory burst, and phenoloxidase. They also activate the cell-mediated immunity by binding to pattern recognition receptors expressed on immune cells and modulating cell signal transduction pathways. Furthermore, the mechanism of action and effectiveness in use of prebiotics and probiotics are summarized in this study, indicating the potential application of prebiotics and probiotics as feed additives in crab farming.

Chemerin receptor 1 (Chemerin₁) plays a critical role in innate and adaptive immune systems. In this study, a cobia (Rachycentron canadum) Chemerin₁ was identified, and its molecular characterization and expression patterns were analyzed. Multiple sequence alignment revealed that the RcChemerin₁ possessed a typical dynein regulatory complex (DRC) motif. There was also a potential N-glycosylation site in the extracellular regions of the N-terminus and intracellular loops (ICL) 1 region. Phylogenetic analysis demonstrated that the RcChemerin₁ was clustered together with homologous proteins from other fish species. RcChemerin₁ was constitutively expressed in a wide range of tissues (especially in immune-related tissues) with different expression levels, which suggests that the RcChemerin₁ plays different roles in un-stimulated tissues. RcChemerin₁ expression showed up-regulation in the head kidney after Vibrio harveyi challenge. Up-regulation in the head kidney and spleen was also observed after polyinosinic-polycytidylic acid (poly I: C) challenge, which suggests that RcChemerin₁ may play vital roles during bacterial and viral infection. The differential responses of immune organs to bacteria and poly I: C imply the differences in defense mechanisms against viruses and bacteria.

Flavobacterium columnare represent one of the most important bacterial pathogens of cultured sturgeon. However, at present there are no commercially available vaccines to prevent infection and treatment options are limited. β-glucans have been shown to be potent immunostimulants that can provide fish protection against infectious disease. In this study, the effects of dietary β-glucan supplementation on disease susceptibility were examined by exposing 0.3% β-glucan-fed white sturgeon (Acipenser transmontanus) to Flavobacterium columnare in laboratory-controlled challenges. Morbidity and mortality were monitored for 15 days post-challenge (dpc). Additionally, transcript levels for pro-inflammatory cytokines, regulatory cytokines and acute phase proteins (APP) were investigated in the spleen and gills at different time points post-challenge. No evidence of protection was observed in β-glucan-fed fish challenged with the bacteria. Moreover, significantly greater mortalities were observed in β-glucan-fed fish challenged with F. columnare (p<0.05), likely associated with acute inflammatory response as haptoglobin and serotransferrin transcripts in the gills were significantly higher in fish within this group at 1 dpc. Transcript levels for all tested cytokines and APP in the spleen were similar amongst treatment groups. The results from this study suggest that β-glucan supplementation at the concentration and rate investigated provides no-benefit to white sturgeon against F. columnare.