Inhibition mechanism of crude lipopeptide from Bacillus subtilis against Aeromonas veronii growth, biofilm formation, and spoilage of channel catfish flesh.

Aeromonas veronii is associated with food spoilage and some human diseases, such as diarrhea, gastroenteritis, hemorrhagic septicemia or asymptomatic and even death. This research investigated the mechanism of the growth, biofilm formation, virulence, stress resistance, and spoilage potential of Bacillus subtilis lipopeptide against Aeromonas veronii. Lipopeptides suppressed the transmembrane transport of Aeromonas veronii by changing the cell membrane's permeability, the structure of membrane proteins, and Na+/K+-ATPase. Lipopeptide significantly reduced the activities of succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) by 86.03% and 56.12%, respectively, ultimately slowing Aeromonas veronii growth. Lipopeptides also restrained biofilm formation by inhibiting Aeromonas veronii motivation and extracellular polysaccharide secretion. Lipopeptides downregulated gene transcriptional levels related to the virulence and stress tolerance of Aeromonas veronii. Furthermore, lipopeptides treatment resulted in a considerable decrease in the extracellular protease activity of Aeromonas veronii, which restrained the decomposing of channel catfish flesh. This research provides new insights into lipopeptides for controlling Aeromonas veronii and improving food safety.

Comparative Analysis of mRNA, microRNA of Transcriptome, and Proteomics on CIK Cells Responses to GCRV and Aeromonas hydrophila.

Grass Carp Reovirus (GCRV) and Aeromonas hydrophila (Ah) are the causative agents of haemorrhagic disease in grass carp. This study aimed to investigate the molecular mechanisms and immune responses at the miRNA, mRNA, and protein levels in grass carp kidney cells (CIK) infected by Grass Carp Reovirus (GCRV, NV) and Aeromonas hydrophilus (Bacteria, NB) to gain insight into their pathogenesis. Within 48 h of infection with Grass Carp Reovirus (GCRV), 99 differentially expressed microRNA (DEMs), 2132 differentially expressed genes (DEGs), and 627 differentially expressed proteins (DEPs) were identified by sequencing; a total of 92 DEMs, 3162 DEGs, and 712 DEPs were identified within 48 h of infection with Aeromonas hydrophila. It is worth noting that most of the DEGs in the NV group were primarily involved in cellular processes, while most of the DEGs in the NB group were associated with metabolic pathways based on KEGG enrichment analysis. This study revealed that the mechanism of a grass carp haemorrhage caused by GCRV infection differs from that caused by the Aeromonas hydrophila infection. An important miRNA-mRNA-protein regulatory network was established based on comprehensive transcriptome and proteome analysis. Furthermore, 14 DEGs and 6 DEMs were randomly selected for the verification of RNA/small RNA-seq data by RT-qPCR. Our study not only contributes to the understanding of the pathogenesis of grass carp CIK cells infected with GCRV and Aeromonas hydrophila, but also serves as a significant reference value for other aquatic animal haemorrhagic diseases.

Genome-Wide Identification and Interaction Analysis of Turbot Heat Shock Protein 40 and 70 Families Suggest the Mechanism of Chaperone Proteins Involved in Immune Response after Bacterial Infection.

Hsp40-Hsp70 typically function in concert as molecular chaperones, and their roles in post-infection immune responses are increasingly recognized. However, in the economically important fish species Scophthalmus maximus (turbot), there is still a lack in the systematic identification, interaction models, and binding site analysis of these proteins. Herein, 62 Hsp40 genes and 16 Hsp70 genes were identified in the turbot at a genome-wide level and were unevenly distributed on 22 chromosomes through chromosomal distribution analysis. Phylogenetic and syntenic analysis provided strong evidence in supporting the orthologies and paralogies of these HSPs. Protein-protein interaction and expression analysis was conducted to predict the expression profile after challenging with Aeromonas salmonicida. dnajb1b and hspa1a were found to have a co-expression trend under infection stresses. Molecular docking was performed using Auto-Dock Tool and PyMOL for this pair of chaperone proteins. It was discovered that in addition to the interaction sites in the J domain, the carboxyl-terminal domain of Hsp40 also plays a crucial role in its interaction with Hsp70. This is important for the mechanistic understanding of the Hsp40-Hsp70 chaperone system, providing a theoretical basis for turbot disease resistance breeding, and effective value for the prevention of certain diseases in turbot.

Characterization of hepcidin gene and protection of recombinant hepcidin supplemented in feed against Aeromonas hydrophila infection in Yellow River carp (Cyprinus carpio haematopterus).

Hepcidin is a small peptide of defensins with antibacterial activity, and plays an important role in innate immunity against pathogenic microorganisms, which can also participate in the regulation of iron metabolism. The hepcidin gene in Yellow River carp (Cyprinus carpio haematopterus) (CcHep) was cloned and identified. The total length of CcHep cDNA was 480 bp, containing an open reading frame (ORF) that encoded 91 amino acids (aa), which contained a 24-aa signal peptide, a 42-aa propeptide, and a 25-aa mature peptide. The mature peptide had a typical RX (K/R) R motif and eight conserved cysteine residues forming four pairs of disulfide bonds. Homology and phylogenetic tree analysis showed that CcHep had the closest relationship with that of crucian carp. The expression levels of hepcidin mRNA in healthy and Aeromonas hydrophila stimulated fish were measured by real-time fluorescence quantitative PCR. The results showed that CcHep mRNA was expressed in different tissues of healthy fish with the highest relative expression level in liver, followed by kidney and intestine, and the lowest expression level was observed in heart. The hepcidin gene was extremely significantly up-regulated in head kidney, intestine, liver, skin, spleen, and gill at 6 h and 12 h after A. hydrophila infection. Furthermore, the immunoregulation effect of dietary recombinant protein was evaluated. The recombinant hepcidin protein (rCcHep) was successfully expressed by Pichia pastoris X-33 and showed strong antibacterial activity against A. hydrophila, Escherichia coli, Vibrio anguillarum and Bacillus subtilis in vitro. In order to evaluate the preventive effect of rCcHep, fish were fed with basal diet or diet supplemented with different doses of rCcHep, and then challenged with A. hydrophila. The results showed that immune genes were up-regulated to varying degrees, and feed additive groups exhibited a significantly improved up-regulation expressions of Lysozyme, Toll-like receptor 5 (TLR 5), Major histocompatibility complex classⅡ (MHCⅡ), while inhibited up-regulation expressions of Interleukin 1ß (IL-1ß), Interleukin 8 (IL-8), and Tumor necrosis factor α (TNF-α) in liver and spleen compared to the control. Meanwhile, the relative immune protection rate in 120 mg/kg feed additive group was 28%, and the bacterial clearance rate in tissues of this group was higher than that of the control. Collectively, these results indicated that rCcHep had antibacterial activity and showed an immune protection effect against A. hydrophila, and could be considered as a dietary supplement to apply in aquaculture.

IL-6 Mutation Attenuates Liver Injury Caused by Aeromonas hydrophila Infection by Reducing Oxidative Stress in Zebrafish.

Interleukin-6 (IL-6), a pleiotropic cytokine, plays a crucial role in acute stress induced by bacterial infection and is strongly associated with reactive oxygen species (ROS) production. However, the role of IL-6 in the liver of fish after Aeromonas hydrophila infection remains unclear. Therefore, this study constructed a zebrafish (Danio rerio) il-6 knockout line by CRISPR/Cas9 to investigate the function of IL-6 in the liver post bacterial infection. After infection with A. hydrophila, pathological observation showed that il-6-/- zebrafish exhibited milder liver damage than wild-type (WT) zebrafish. Moreover, liver transcriptome sequencing revealed that 2432 genes were significantly up-regulated and 1706 genes were significantly down-regulated in il-6-/- fish compared with WT fish after A. hydrophila infection. Further, gene ontology (GO) analysis showed that differentially expressed genes (DEGs) were significantly enriched in redox-related terms, including oxidoreductase activity, copper ion transport, etc. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that DEGs were significantly enriched in pathways such as the PPAR signaling pathway, suggesting that il-6 mutation has a significant effect on redox processes in the liver after A. hydrophila infection. Additionally, il-6-/- zebrafish exhibited lower malondialdehyde (MDA) levels and higher superoxide dismutase (SOD) activities in the liver compared with WT zebrafish following A. hydrophila infection, indicating that IL-6 deficiency mitigates oxidative stress induced by A. hydrophila infection in the liver. These findings provide a basis for further studies on the role of IL-6 in regulating oxidative stress in response to bacterial infections.

Analysis of global Aeromonas veronii genomes provides novel information on source of infection and virulence in human gastrointestinal diseases.

BACKGROUND: Aeromonas veronii is a Gram-negative rod-shaped motile bacterium that inhabits mainly freshwater environments. A. veronii is a pathogen of aquatic animals, causing diseases in fish. A. veronii is also an emerging human enteric pathogen, causing mainly gastroenteritis with various severities and also often being detected in patients with inflammatory bowel disease. Currently, limited information is available on the genomic information of A. veronii strains that cause human gastrointestinal diseases. Here we sequenced, assembled and analysed 25 genomes (one complete genome and 24 draft genomes) of A. veronii strains isolated from patients with gastrointestinal diseases using combine sequencing technologies from Illumina and Oxford Nanopore. We also conducted comparative analysis of genomes of 168 global A. veronii strains isolated from different sources. RESULTS: We found that most of the A. veronii strains isolated from patients with gastrointestinal diseases were closely related to each other, and the remaining were closely related to strains from other sources. Nearly 300 putative virulence factors were identified. Aerolysin, microbial collagenase and multiple hemolysins were present in all strains isolated from patients with gastrointestinal diseases. Type III Secretory System (T3SS) in A. veronii was in AVI-1 genomic island identified in this study, most likely acquired via horizontal transfer from other Aeromonas species. T3SS was significantly less present in A. veronii strains isolated from patients with gastrointestinal diseases as compared to strains isolated from fish and domestic animals. CONCLUSIONS: This study provides novel information on source of infection and virulence of A. veronii in human gastrointestinal diseases.

Disrupted tongue microbiota and detection of nonindigenous bacteria on the day of allogeneic hematopoietic stem cell transplantation.

Disruption of the intestinal microbiota caused by intensive chemotherapy, irradiation and antibiotics can result in development of severe gut graft-versus-host disease and infectious complications, leading to poorer outcomes among allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Although the oral cavity is also densely colonized by indigenous microorganisms, the bacterial composition in allo-HSCT recipients remains unclear. We determined the tongue microbiota composition of 45 patients with hematological disorders on the day of transplantation and compared them to 164 community-dwelling adults. The V1-V2 regions of the 16S rRNA gene sequences demonstrated that the allo-HSCT recipients had less diverse and distinct microbiota from that of community-dwelling adults. The full-length 16S rRNA gene sequences identified 146 bacterial taxa in the microbiota of allo-HSCT recipients, of which 34 bacterial taxa did not correspond to bacteria primarily inhabiting the oral cavity deposited in the expanded Human Oral Microbiome Database. Notably, the detection of Staphylococcus haemolyticus and/or Ralstonia pickettii was significantly associated with a higher risk of mortality during the follow-up period. These results demonstrate that the oral cavity of allo-HSCT recipients is colonized by a disrupted microbiota on the day of transplantation and suggest that detection of specific nonindigenous taxa could be a predictor of transplant outcome.

Transcriptome profiles discriminate between Gram-positive and Gram-negative sepsis in preterm neonates.

BACKGROUND: Genome-wide expression profiles have been previously employed as clinical research diagnostic tools for newborn sepsis. We aimed to determine if transcriptomic profiles could discriminate between Gram-positive and Gram-negative bacterial sepsis in preterm infants. METHODS: Prospective, observational, double-cohort study was conducted in very low birth weight infants with clinical signs and culture-positive sepsis. Blood samples were collected when clinical signs became apparent. Total RNA was processed for transcriptomic analysis. Results were validated by both reverse-transcription polymerase chain reaction and a mathematical model. RESULTS: We included 25 septic preterm infants, 17 with Gram-positive and 8 with Gram-negative bacteria. The principal component analysis identified these two clusters of patients. We performed a predictive model based on 21 genes that showed an area under the receiver-operating characteristic curve of 1. Eight genes were overexpressed in Gram-positive septic infants: CD37, CSK, MAN2B2, MGAT1, MOB3A, MYO9B, SH2D3C, and TEP1. The most significantly overexpressed pathways were related to metabolic and immunomodulating responses that translated into an equilibrium between pro- and anti-inflammatory responses. CONCLUSIONS: The transcriptomic profile allowed identification of whether the causative agent was Gram-positive or Gram-negative bacteria. The overexpression of genes such as CD37 and CSK, which control cytokine production and cell survival, could explain the better clinical outcome in sepsis caused by Gram-positive bacteria. IMPACT: Transcriptomic profiles not only enable an early diagnosis of sepsis in very low birth weight infants but also discriminate between Gram-positive and Gram-negative bacteria as causative agents. The overexpression of some genes related to cytokine production and cell survival could explain the better clinical outcome in sepsis caused by Gram-positive bacteria, and could lead us to a future, targeted therapy.

Long non-coding RNAs are involved in immune resistance to Aeromonas hydrophila in black carp (Mylopharyngodon piceus).

A growing number of studies identified long non-coding RNAs (lncRNAs) to be closely associated with immune function through the regulation of immune cell differentiation and immune cell effector function. Here we tested whether lncRNAs are involved in immune function in black carp (Mylopharyngodon piceus) through the exposure to Aeromonas hydrophila and analysis of the spleen gene expression response using RNA-seq. A total of 9036 lncRNAs were identified with high confidence. Differential expression analysis identified a total of 3558 DElncRNAs (Differential expression lncRNA) involved in A. hydrophila infection and 4526 target genes corresponding to DElncRNAs. After screening 4526 target genes in the InnateDB database, a total of 150 immunity genes were identified. After GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis of the obtained immunity genes, the Toll-like receptor (TLR) signaling pathway, TLR2, TLR3, TLR5, and TLR8 were identified as particularly significant in A. hydrophyla-resistant black carp. At the same time, the Ras signaling pathway was particularly enriched in the spleen of susceptible black carp. Analysis of PPI (protein-protein interaction) networks of the obtained immune genes identified SRC (SRC Proto-Oncogene), MYD88 (Myeloid differentiation primary response 88), MAPK3 (Mitogen-Activated Protein Kinase 3), MYC (MYC Proto-Oncogene) as main hub genes regulated by lncRNA and possibly mediating a mechanism of susceptibility to bacteria. These results establish a functional role of lncRNAs and a mechanistic base for the immune response in black carp resistant to A. hydrophila.

Cloning and characterization of linker histone H1 gene in rohu, Labeo rohita.

Linker histone H1 (LHH1) is an abundant nuclear protein that condenses chromatin to form higher-order structure. The present study reported cloning and sequencing of 942 bp of LHH1 from liver tissue of rohu, Labeo rohita, with a complete coding sequence of 792 bp of having 263 amino acids. The phylogenetic tree of L. rohita LHH1 (LrLHH1) shared maximum similarity with that of Carassius auratus. The three dimensional model and domain architecture of LrLHH1 protein was also predicted using Swiss-Prot and SMART domain software. The expression of LHH1 during ontogeny showed significantly higher transcript level in milt, unfertilized eggs and up to 3 h post-fertilization followed by a dramatic decrease thereafter. The tissue-specific expression showed constitutive expression of LrLHH1 in all examined tissues. The expression of LHH1 during different infection models, namely, bacteria (Aeromonas hydrophila); ectoparasite (Argulus siamensis) and poly I:C induction revealed modulation in the level of expression at varied time points post-exposure in the liver and anterior kidney tissues of rohu. However, a synthetic peptide derived from LHH1 sequence of rohu did not have any detectable antibacterial activity. The present study provided necessary information on the role of this protein during ontogeny and innate immunity in Indian major carp species.

Molecular Characterization, Expression, Evolutionary Selection, and Biological Activity Analysis of CD68 Gene from Megalobrama amblycephala.

CD68 is a highly glycosylated transmembrane glycoprotein that belongs to the lysosome-associated membrane glycoprotein family and is involved in various immune processes. In this study, Megalobrama amblycephala CD68 (MaCD68) was cloned and characterized, and its expression patterns and evolutionary characteristics were analyzed. The coding region of MaCD68 was 987 bp, encoding 328 amino acids, and the predicted protein molecular weight was 34.9 kDa. MaCD68 contained two transmembrane helical structures and 18 predicted N-glycosylation sites. Multiple sequence alignments showed that the MaCD68 protein had high homology with other fish, and their functional sites were also highly conserved. Phylogenetic analysis revealed that MaCD68 and other cypriniformes fish clustered into one branch. Adaptive evolution analysis identified several positively selected sites of teleost CD68 using site and branch-site models, indicating that it was under positive selection pressure during evolution. Quantitative real-time reverse transcription polymerase chain reaction analysis showed that MaCD68 was highly expressed in the head kidney, spleen, and heart. After Aeromonas hydrophila infection, MaCD68 was significantly upregulated in all tested tissues, peaking at 12 h post-infection (hpi) in the kidney and head kidney and at 120 hpi in the liver and spleen, suggesting that MaCD68 participated in the innate immune response of the host against bacterial infection. Immunohistochemical and immunofluorescence analyses also showed that positive signals derived from the MaCD68 protein were further enhanced after bacterial and lipopolysaccharide treatment, which suggested that MaCD68 is involved in the immune response and could be used as a macrophage marker. Biological activity analysis indicated that recombinant MaCD68 (rMaCD68) protein had no agglutination or bactericidal effects on A. hydrophila but did have these effects on Escherichia coli. In conclusion, these results suggest that MaCD68 plays a vital role in the immune response against pathogens, which is helpful in understanding the immune responses and mechanisms of M. amblycephala.

MiRNA-seq analysis of spleen and head kidney tissue from aquacultured largemouth bass (Micropterus salmoides) in response to Aeromonas hydrophila infection.

Recently, the same fish diseases, which have been found in pond farming, have been found in the newly tested largemouth bass (Micropterus salmoides) system. Bacterial septicemia caused by Aeromonas hydrophila occurs frequently in largemouth bass culture leading to significant economic losses. To investigate the role miRNA in the largemouth bass disease resistance, twelve (2 tissues (spleen and head kidney) × 2 experimental groups (infected and control) × three biological replicates) small RNA libraries were constructed and sequenced with miRNA-seq. A total of 26 differentially expressed miRNAs, 8 upregulated and 18 downregulated, were identified in the spleen, and 19 differentially expressed miRNAs, 9 upregulated and 10 downregulated, were identified in head kidney (fold change ≥ 2 or ≤ 0.5 and P ≤ 0.05). The differentially expressed miRNAs with the largest fold change were selected for target gene prediction using GO and KEGG analysis. Six miRNAs in the spleen and 5 miRNAs in the head kidney were selected. Analysis showed that, of all the immune and metabolic pathways, the FoxO signaling pathway was enriched in both the spleen and head kidney groups. Common target genes of the pathway included AMP-activated catalytic subunit alpha 1 (prkaa1), phosphatidylinositol 3-kinase (pik3r3b), serine/threonine-protein kinase (plk2), and forkhead box protein G1 (foxg1a). MiRNAs (such as miR-126-5P, miR-126-3P) are involved in immune response and cell cycle functions as they regulate targeted genes in the FoxO pathway. These results will enhance our understanding of the molecular mechanisms underlying immune responses to bacterial septicemia and facilitate molecular-assisted selection of resistant strains of largemouth bass.

LncRNA-WAS and lncRNA-C8807 interact with miR-142a-3p to regulate the inflammatory response in grass carp.

Septicemia of grass carp is a systemic inflammatory reaction caused by bacterial infection. More and more evidences show that long non-coding RNAs (lncRNAs) can participate in the regulation of inflammatory response. In the present study, lncRNA-WAS and lncRNA-C8807 were confirmed to be involved in the inflammatory response following infection with Aeromonas hydrophila. LncRNA-WAS and lncRNA-C8807 could interact with miR-142a-3p. LncRNA-WAS and lncRNA-C8807 interact with miR-142a-3p to effect pro-inflammatory genes and NF-κB pathway. Our results provide a theoretical basis for studying the molecular mechanism underlying the regulation of inflammation by lncRNA in grass carp.

A novel NK-lysin in hybrid crucian carp can exhibit cytotoxic activity in fish cells and confer protection against Aeromonas hydrophila infection in comparison with Carassius cuvieri and Carassius auratus red var.

NK-lysin, an effector of natural killer (NK) cells and cytotoxic T lymphocytes (CTLs), not only exhibits cytotoxic effect in fish cells, but also participates in the immune defense against pathogenic infection. In this study, ORF sequences of RCC-NK-lysin, WCC-NK-lysin and WR-NK-lysin were 369 bp. Tissue-specific analysis revealed that the highest expressions of RCC-NK-lysin and WCC-NK-lysin were observed in gill, while the peaked level of WR-NK-lysin mRNA was observed in spleen. A. hydrophila infection sharply increased RCC-NK-lysin, WCC-NK-lysin and WR-NK-lysin mRNA expression in liver, trunk kidney and spleen. In addition, elevated levels of NK-lysin mRNA were observed in cultured fin cell lines of red crucian carp (RCC), white crucian carp (WCC) and their hybrid offspring (WR) after Lipopolysaccharide (LPS) challenge. RCC-NK-lysin, WCC-NK-lysin and WR-NK-lysin exerted regulatory roles in inducing ROS generation, modulating mitochondrial membrane potential, decreasing fish cell viability and antagonizing survival signalings, respectively. RCC/WCC/WR-NK-lysin-overexpressing fish could up-regulate expressions of inflammatory cytokines and decrease bacterial loads in spleen. These results indicated that NK-lysin in hybrid fish contained close sequence similarity to those of its parents, possessing the capacities of cytotoxicity and immune defense against bacterial infection.

First case report of Anaerobiospirillum succiniciproducens bacteremia in an HIV-infected patient in Taiwan - Molecular identification from a positive blood culture bottle.

Anaerobiospirillum succiniciproducens is a gram-negative, spiral-shaped anaerobe, that is a rare but potentially lethal cause of bacteremia in humans, particularly in immunocompromised hosts. We reported a 69-year-old HIV-infected male presenting with dysphagia, odynophagia and fulminant pneumonia who died. In addition, in a literature review, we summarized the characteristics of 19 adult patients with A. succiniciproducens bacteremia, which were confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry or molecular methods. Among those, the presentation of gastrointestinal conditions was the only independent risk factor for mortality. Clinicians should be aware of this pathogen, especially when a culture is negative but a Gram stain reveals gram-negative spiral-shaped bacteria.

Development of a SNP linkage map and genome-wide association study for resistance to Aeromonas hydrophila in pacu (Piaractus mesopotamicus).

BACKGROUND: Pacu (Piaractus mesopotamicus) is one of the most important Neotropical aquaculture species from South America. Disease outbreaks caused by Aeromonas hydrophila infection have been considered significant contributors to the declining levels of pacu production. The current implementation of genomic selection for disease resistance has been adopted as a powerful strategy for improvement in fish species. This study aimed to investigate the genetic architecture of resistance to A. hydrophila in pacu via Genome-Wide Association Study (GWAS), the identification of suggestive Quantitative Trait Loci (QTLs) and putative genes associated with this trait. The genetic data were obtained from 381 juvenile individuals belonging to 14 full-sibling families. An experimental challenge was performed to gain access to the levels of genetic variation for resistance against the bacteria using the following trait definitions: binary test survival (TS) and time of death (TD). RESULTS: The analyses of genetic parameters estimated moderate heritability (h2) for both resistance traits: 0.20 (± 0.09) for TS and 0.35 (± 0.15) for TD. A linkage map for pacu was developed to enable the GWAS, resulting in 27 linkage groups (LGs) with 17,453 mapped Single Nucleotide Polymorphisms (SNPs). The length of the LGs varied from 79.95 (LG14) to 137.01 (LG1) cM, with a total map length of 2755.60 cM. GWAS identified 22 putative QTLs associated to A. hydrophila resistance. They were distributed into 17 LGs, and were considered suggestive genomic regions explaining > 1% of the additive genetic variance (AGV) for the trait. Several candidate genes related to immune response were located close to the suggestive QTLs, such as tbk1, trim16, Il12rb2 and lyz2. CONCLUSION: This study describes the development of the first medium density linkage map for pacu, which will be used as a framework to study relevant traits to the production of this species. In addition, the resistance to A. hydrophila was found to be moderately heritable but with a polygenic architecture suggesting that genomic selection, instead of marker assisted selection, might be useful for efficiently improving resistance to one of the most problematic diseases that affects the South American aquaculture.

Overwhelming sepsis in a neonate affected by Zellweger syndrome due to a compound heterozygosis in PEX 6 gene: a case report.

BACKGROUND: Peroxisome biogenesis disorders (PBDs) are a group of metabolic diseases caused by dysfunction of peroxisomes. Different forms of PBDs are described; the most severe one is the Zellweger syndrome (ZS). We report on an unusual presentation of Zellweger syndrome manifesting in a newborn with severe and fulminant sepsis, causing death during the neonatal period. CASE PRESENTATION: A term male Caucasian neonate presented at birth with hypotonia and poor feeding associated with dysmorphic craniofacial features and skeletal abnormalities. Blood tests showed progressive leukopenia; ultrasounds revealed cerebral and renal abnormalities. He died on the fourth day of life because of an irreversible Gram-negative sepsis. Post-mortem tests on blood and urine samples showed biochemical alterations suggestive of ZS confirmed by genetic test. CONCLUSIONS: ZS is an early and severe forms of PBDs. Peroxisomes are known to be involved in lipid metabolism, but recent studies suggest their fundamental role in modulating immune response and inflammation. In case of clinical suspicion of ZS it is important to focus the attention on the prevention and management of infections that can rapidly progress to death.

Serum amyloid A promotes LPS clearance and suppresses LPS-induced inflammation and tissue injury.

Lipopolysaccharide (LPS) is a major microbial mediator for tissue injury and sepsis resulting from Gram-negative bacterial infection. LPS is an external factor that induces robust expression of serum amyloid A (SAA), a major constituent of the acute-phase proteins, but the relationship between SAA expression and LPS-induced tissue injury remains unclear. Here, we report that mice with inducible transgenic expression of human SAA1 are partially protected against inflammatory response and lung injury caused by LPS and cecal ligation and puncture (CLP). In comparison, transgenic SAA1 does not attenuate TNFα-induced lung inflammation and injury. The SAA1 expression level correlates inversely with the endotoxin concentrations in serum and lung tissues since SAA1 binds directly to LPS to form a complex that promotes LPS uptake by macrophages. Disruption of the SAA1-LPS interaction with a SAA1-derived peptide partially reduces the protective effect and exacerbates inflammation. These findings demonstrate that acute-phase SAA provides innate feedback protection against LPS-induced inflammation and tissue injury.

Genome-wide characterization of TNF receptor-associated factors in the Chinese soft-shelled turtle Pelodiscus sinensis and their expression profiling in response to Aeromonas hydrophila challenge.

Tumor necrosis factor receptor (TNFR)-associated factors (TRAFs) are a family of crucial signaling molecules that mediate the signal transduction of various immune signaling pathways. Extensive studies have demonstrated that TRAFs play vital roles in regulating cellular immune responses. However, the biological functions and expression profiling of TRAFs in Chinese soft-shelled turtle (Pelodiscus sinensis) remain unclear. In this study, the genes of the PsTRAF family at the genome-wide level were identified in P. sinensis, revealing six PsTRAF members that contained the conserved TRAF domain in the C-terminal regions. Molecular evolutionary analysis showed that PsTRAFs shared close evolutionary relationships and similar protein crystal structures with the TRAF homologs from other turtles, indicating the evolutionary conservation of PsTRAFs. Further expression analysis revealed the tissue-specific expression of PsTRAF genes. Obvious variations in the expression of PsTRAF genes were observed in the spleen in response to Aeromonas hydrophila infection. Three PsTRAF genes, PsTRAF2, PsTRAF3, and PsTRAF6, were significantly upregulated at the mRNA and protein levels post-infection, indicating their potential function in the immune response. Moreover, the protein-protein associations of PsTRAFs with several signaling receptors were predicted in P. sinensis. These results provide a basis for the investigation of the functional roles of PsTRAFs in immune defense against bacterial infection.

Phylogeny of Slc15 family and response to Aeromonas hydrophila infection following Lactococcus lactis dietary supplementation in Cyprinus carpio.

Solute carrier 15 family (Slc15) are membrane proteins that utilize the proton gradient and negative membrane protential for the transmembrane transporter of di-/tripeptide and peptide-mimetic molecules, in addition, they also play important roles in immunoreaction. In this study, 10 Slc15 genes were identified in the common carp genome database. Comparative genomics analysis showed considerable expansion of the Slc15 genes and verified the four-round whole genome duplication (WGD) event in common carp. Phylogenetic analysis revealed all Slc15 genes of common carp were clustered into orthologous groups indicating the highly conservative during evolution. Besides, the tissues and temporal expression examined by RT-PCR and qRT-PCR showed that most of the Slc15 genes had a narrow tissue distribution and exhibited tissue-specific expression patterns. Expression divergences were observed between these copies proving function divergence after the WGD. Then, we investigated the dietary supplementation effects of three Lactococcus lactis strains on the expression of Slc15 genes in common carp infected by A. hydrophila to find an effective way to treat aquatic diseases. Almost all of the Slc15 genes had an increased expression trend in the early post-challenge stage, and reached the highest expression level at 12h post-challenge. Then, the expression level showed a bluff descent at the last two stages and the expression level reached the lowest at 48 h post-challenge. Slc15 genes expression is actively up-regulated when stimulated by inflammatory factors, which can "amplify" immune signals, and improve the body's defense against foreign invasion in the early stage of the inflammatory response. So activation of the Slc15 genes may be an effective way for infectious disease treatment. As expected, three strains improved the expression of Slc15 genes variously compared with the control/infection groups. The strain 3 of L. lactis had a better induction of Slc15 genes compared with strain 1 and strain 2. It might be applied as a potential activation of Slc15 genes for disease treatment and adding befitting L. lactis may be a good way to protect aquatilia from bacillosis.