Multiomics Analyses Explore the Immunometabolic Interplay in the Liver of White Crucian Carp (Carassius cuvieri) After Aeromonas veronii Challenge.

Aeromonas veronii is one of the predominant pathogenic species that can imperil the survival of farmed fish. However, the interactive networks of immune regulation and metabolic response in A. veronii-infected fish are still unclear. In this investigation, we aimed to explore immunometabolic interplay in white crucian carp (WCC) after the A. veronii challenge. Elevated levels of immune-related genes were observed in various tissues after A. veronii infection, along with the sharp alteration of disease-related enzymatic activities. Besides, decreased levels of antioxidant status were observed in the liver, but most metabolic gene expressions increased dramatically. Multiomics analyses revealed that metabolic products of amino acids, such as formiminoglutamic acid (FIGLU), L-glutamate (L-Glu), and 4-hydroxyhippuric acid, were considered the crucial liver biomarkers in A. veronii-infected WCC. In addition, A. veronii infection may dysregulate endoplasmic reticulum (ER) function to affect the metabolic process of lipids, carbohydrates, and amino acids in the liver of WCC. These results may have a comprehensive implication for understanding immunometabolic response in WCC upon A. veronii infection.

Comparative genomics of IncQ1 plasmids carrying blaGES variants from clinical and environmental sources in Brazil.

IncQ-type plasmids have become important vectors in the dissemination of blaGES among different bacterial genera and species from different environments around the world, and studies estimating the occurrence of Guiana extended-spectrum (GES)-type ß-lactamases are gaining prominence. We analyzed the genetic aspects of two IncQ1 plasmids harboring different blaGES variants from human and environmental sources. The blaGES variants were identified using polymerase chain reaction (PCR) in Aeromonas veronii isolated from hospital effluent and Klebsiella variicola isolated from a rectal swab of a patient admitted to the cardiovascular intensive care unit in a different hospital. Antimicrobial-susceptibility testing and transformation experiments were performed for phenotypic analysis. Whole-genome sequencing was performed using Illumina and Oxford Nanopore platforms. The comparative analysis of plasmids was performed using BLASTn, and the IncQ1 plasmids showed a high identity and similar size. A. veronii harbored blaGES-7 in a class 1 integron (In2061), recently described by our group, and K. variicola carried blaGES-5 in the known class 1 integron. Both integrons showed a fused gene cassette that encodes resistance to aminoglycosides and fluoroquinolones, with an IS6100 truncating the 3'-conserved segment. The fused genes are transcribed together, although the attC site is disrupted. These gene cassettes can no longer be mobilized. This study revealed a mobilome that may contribute to the dissemination of GES-type ß-lactamases in Brazil. Class 1 integrons are hot spots for bacterial evolution, and their insertion into small IncQ-like plasmids displayed successful recombination, allowing the spread of blaGES variants in various environments. Therefore, they can become prevalent across clinically relevant pathogens.

Comparative transcriptome reveals importance of export apparatus subunit (ascR) in type III secretion system and its roles on biological properties, gene expression profiles, virulence and colonization of Aeromonas veronii.

Aeromonas veronii, an opportunistic pathogen, is known to cause serious infections across various species. In our previous study, we discovered that A. veronii GL2 exhibited a virulence up to ten times greater than that of FO1. To ascertain the factors contributing to the disparity in virulence between the two strains, we conducted a comparative transcriptome analysis. This analysis reveals a significant upregulation (P < 0.05) of the ascR gene in GL2 compared with FO1. Additionally, six differentially expressed genes (DEGs) were identified within the "Bacterial secretion system" pathway (map03070), with ascR being an essential component of type III secretion system (T3SS). AscR, considered as SctR family export apparatus subunit within the T3SS, has ambiguous roles in the biological properties, gene expression profiles, virulence and colonization of A. veronii. Therefore, we constructed a mutant strain (ΔascR) by homologous recombination. Comparative analysis with the wide-type GL2 reveals no significant differences in terms of colony morphology, growth curve, hemolytic activity and protease activity. However, significant reductions (P < 0.01) were observed in the abilities of biofilm formation and swimming mobility. No remarkable difference was noted in the lengths of flagella. The LD50 value of ΔascR was to be 5.15 times higher than that of GL2. Interestingly, the mRNA expression of ascC, ascD, ascJ and ascI genes in the T3SS, and mshB, mshE, mshK and mshP genes in the MSHA type pili were significantly upregulated (P < 0.05) in ΔascR, potentially due to transcriptional compensation. Further analysis of enzymatic biomarkers revealed that ΔascR might not destruct the recognition of innate immune response in host remarkably, but the colonization levels of A.veronii were significantly suppressed (P < 0.01) in ΔascR group. In conclusion, the ascR gene may be a key determinant in regulating the virulence of A. veronii, and the destruction of the T3SS caused by ascR deficiency results in these notable changes.

The Hanks-like serine/threonine protein kinase YihE is crucial for Aeromonas veronii virulence and adhesion.

Aeromonas veronii is an important pathogen found in various aquatic environments and products, posing a threat to public health. The Hanks-like serine/threonine protein kinase is closely linked to the pathogenesis of pathogenic bacteria, but the exact role of YihE in A. veronii remains still unknown. To study the specific function of the YihE kinase, we constructed a knockout mutant of the yihE gene in A. veronii. The deletion of the yihE gene resulted in changes to the metabolism of L-arginine-AMC and acetic acid, as well as enhanced resistance to ampicillin and kanamycin in A. veronii. Additionally, the ΔyihE strain demonstrated a 1.4-fold increase in biofilm formation ability and a 1.8-fold decrease in adhesion and invasion to EPCs when compared to the wild-type strain. A significant decrease in cytotoxicity was observed at 2 and 3 h post-infection with EPCs compared to the wild-type strain. Additionally, the deletion of the yihE gene was associated with a significant decrease in motility of the strain. Furthermore, the deletion of the yihE gene resulted in a 1.44-fold increase in the LD50 of A. veronii in zebrafish. These findings offer valuable insights into the pathogenic mechanisms of A. veronii.

Interleukin-1 beta (IL-1ß) as adjuvant enhances the immune effects of Aeromonas veronii inactivated vaccine in largemouth bass (Micropterus salmoides).

Largemouth bass (Micropterus salmoides) has emerged as a significant economic fish species, with a rise in Aeromonas veronii infections in farming. However, research on adjuvants for vaccines against A. veronii in largemouth bass remains scarce. In present study, recombinant largemouth bass IL-1ß (LbIL-1ß) was expressed to explore its adjuvant effect on the A. veronii inactivated vaccine. Following vaccination with recombinant LbIL-1ß (rLbIL-1ß) and the inactivated A. veronii, higher serum SOD levels and lysozyme activities were observed in largemouth bass from inactivated A. veronii + rLbIL-1ß vaccinated group. Furthermore, it was discovered that rLbIL-1ß was able to boost the serum-specific antibody levels induced by the inactivated A. veronii. The qRT-PCR analysis revealed that rLbIL-1ß also enhanced the expression of IgM, CD4, and MHC II in largemouth bass triggered by the inactivated A. veronii. After challenged with live A. veronii, the outcomes demonstrated that the relative percentage survival (RPS) for largemouth bass resulting from the inactivated A. veronii in combination with rLbIL-1ß was 76.67 %, surpassing the RPS of 60 % in the inactivated A. veronii group. Collectively, these findings indicate that rLbIL-1ß enhances the protective effect of the A. veronii inactivated vaccine on largemouth bass, showcasing potential as an adjuvant for further development.

Influence of Herba Houttuyniae added to fodder on the morphological structure of the intestinal tract, the digestive enzymes, the intestinal flora, and immune function of koi carp (Cyprinus carpio) infected with Aeromonas veronii.

This study investigated whether adding Herba Houttuyniae to feed can improve intestinal function and prevent diseases for koi carp (Cyprinus carpio) infected with Aeromonas veronii. There was a total of 168 koi carp with an average body length of (9.43 ± 0.99) cm and an average body weight of (26.00 ± 11.40) g. The K group was the control group fed with basal feed, while the C group was fed with feed with a H. houttuyniae content of six per thousand. After 14 days of feeding, the fish were fasted for a day and then intraperitoneally injected with A. veronii for artificial infection, injection dose is 0.2 mL, and the concentration is 1 × 107 CFU/mL. Samples were collected from the two groups on days 0, 1, 2, and 4. The fold height, intestinal villus width, and muscle layer thickness in the gut of the koi carp were measured. In addition, on day 4, the activities of trypsin, α-amylase, and lipase in the gut were determined, and the intestinal flora of the carp in both groups was tested. The results showed that on the second and fourth days of sampling, the fold height and muscle layer thickness in the C group were significantly higher than those in the K group (P < 0.05). The villus width in the C group was slightly higher than that in the K group, but the difference was not significant (P > 0.05). Microscopic observation revealed that the intestinal structure of the carp in the C4 (day 4 in C group) group was more intact than that in the K4 (day 4 in K group) group. Moreover, the activities of trypsin, α-amylase, and lipase in the foregut and midgut in the C4 group were higher than those in the K4 group (P < 0.05). The activities of trypsin and α-amylase in the hindgut in the C4 group were higher than those in the K4 group (P < 0.05). Furthermore, beneficial bacteria, especially those in the genus Cetobacterium, were more abundant in the intestinal tract of the carp in the C4 group compared to the K group. In addition, comparisons and tests of IL-4 and IL-10 in the intestines of the fish in both groups demonstrated that the H. houttuyniae added to feed enhanced the immune function of the fish intestines after bacterial attack. In conclusion, for koi carp infected with A.veronii, adding H. houttuyniae to their feed not only improves the activity of digestive enzymes and the morphological structure of the intestine but also optimizes the beneficial intestinal microbiota, thereby protecting the intestinal tract.

Effects of phoxim on antibacterial infection of silver carp.

The efficacy of phoxim in treating bacterial sepsis in silver carp is significant, yet its underlying mechanism remains elusive. This study aimed to establish a model of Aeromonas veronii infection in silver carp and subsequently treat the infected fish with 10 µg/L phoxim. Kidney and intestine samples from silver carp were collected for transcriptome analysis and assessment of intestinal microbial composition, with the aim of elucidating the mechanism underlying the efficacy of phoxim in treating bacterial sepsis in silver carp. The results of transcriptome and intestinal microbial composition analysis of silver carp kidney indicated that A. veronii infection could up-regulate the expression of il1ß, il6, nos2, ctsl, casp3 et al., which means, signifying that the kidney of silver carp would undergo inflammation, induce apoptosis, and alter the composition of intestinal microorganisms. Phoxim immersion might enhance the energy metabolism of silver carp and change its intestinal microbial composition, potentially elevating the antibacterial infection resistance of silver carp. These findings may contribute to an understanding of how phoxim can effectively treat bacterial sepsis in silver carp.

Systematic identification and analysis of immune-related circRNAs of Pelteobagrus fulvidraco involved in Aeromonas veronii infection.

Circular RNA (circRNA) represents a type of newly discovered non-coding RNA, distinguished by its closed loop structure formed through covalent bonds. Recent studies have revealed that circRNAs have crucial influences on host anti-pathogen responses. Yellow catfish (Pelteobagrus fulvidraco), an important aquaculture fish with great economic value, is susceptible to Aeromonas veronii, a common aquatic pathogen that can cause acute death. Here, we reported the first systematic investigation of circRNAs in yellow catfish, especially those associated with A. veronii infection at different time points. A total of 1205 circRNAs were identified, which were generated from 875 parental genes. After infection, 47 circRNAs exhibited differential expression patterns (named DEcirs). The parental genes of these DEcirs were functionally engaged in immune-related processes. Accordingly, seven DEcirs (novel_circ_000226, 278, 401, 522, 736, 843, and 975) and six corresponding parental genes (ADAMTS13, HAMP1, ANG3, APOA1, FGB, and RALGPS1) associated with immunity were obtained, and their expression was confirmed by RT-qPCR. Moreover, we found that these DEcir-gene pairs likely acted through pathways, such as platelet activation, antimicrobial humoral response, and regulation of Ral protein signal transduction, to influence host immune defenses. Additionally, integrated analysis showed that, of the 7 immune-related DEcirs, three targeted 16 miRNAs, which intertwined into circRNA-miRNA networks. These findings revealed that circRNAs, by targeting genes or miRNAs are highly involved in anti-bacterial responses in yellow catfish. Our study comprehensively illustrates the roles of circRNAs in yellow catfish immune defenses. The identified DEcirs and the circRNA-miRNA network will contribute to the further investigations on the molecular mechanisms underlying yellow catfish immune responses.

The therapeutic role of Azadirachta indica leaves ethanolic extract against detrimental effects of Aeromonas veronii infection in Nile tilapia, Oreochromis niloticus.

Bacterial pathogens cause high fish mortalities and in turn economic losses in fish farms. Innovative strategies should be applied to control bacterial infections instead of antibiotics to avoid the resistance problem. Consequently, the present investigation studied the curative potential of Azadirachta indica leave ethanolic extract (AILEE) on Aeromonas veronii infection in Oreochromis niloticus. A preliminary trial was assessed to evaluate the curative dose of AILEE which was found to be 2.5 mg/L. One hundred and sixty fish were divided into equal four groups in four replications, where group 1 and group 2 were non-challenged and treated with 0- and 2.5-mg/L AILEE, respectively. Group 3 and group 4 were challenged with A. veronii and treated with 0- and 2.5-mg/L AILEE, respectively for 10 days. A. veronii infection produced severe clinical manifestations and a high mortality rate in the infected fish. Furthermore, the infected fish exhibited a significant rise in the hepatorenal indices (aspartate aminotransferase, alanine aminotransferase, and creatinine), the oxidant biomarker (malondialdehyde), and the stress indicators (glucose and cortisol). A significant reduction in the protein profile and antioxidant/immune parameters (catalase, immunoglobulin M, lysozyme, nitric oxide, and phagocytic activity) was observed in the infected fish. Water application of the infected group to 2.5-mg/L AILEE notably ameliorated the hepatorenal indices, the oxidant biomarker, and the stress indicators. Furthermore, AILEE improved the antioxidant/immune indices. Water application of 2.5-mg/L AILEE could be useful against A. veronii infection in O. niloticus culture.

Pathogenicity of Aeromonas veronii Isolated from Diseased Macrobrachium rosenbergii and Host Immune-Related Gene Expression Profiles.

Aeromonas veronii is widespread in aquatic environments and is responsible for infecting various aquatic animals. In this study, a dominant strain was isolated from the hepatopancreas of diseased Macrobrachium rosenbergii and was named JDM1-1. According to its morphological, physiological, and biochemical characteristics and molecular identification, isolate JDM1-1 was identified as A. veronii. The results of artificial challenge showed isolate JDM1-1 had high pathogenicity to M. rosenbergii with an LD50 value of 8.35 × 105 CFU/mL during the challenge test. Histopathological analysis revealed severe damage in the hepatopancreas and gills of the diseased prawns, characterized by the enlargement of the hepatic tubule lumen and gaps between the tubules as well as clubbing and degeneration observed at the distal end of the gill filament. Eight virulence-related genes, namely aer, ompA, lip, tapA, hlyA, flgA, flgM, and flgN, were screened by PCR assay. In addition, virulence factor detection showed that the JDM1-1 isolate produced lipase, lecithinase, gelatinase, and hemolysin. Furthermore, the mRNA expression profiles of immune-related genes of M. rosenbergii following A. veronii infection, including ALF1, ALF2, Crustin, C-lectin, and Lysozyme, were assessed, and the results revealed a significant upregulation in the hepatopancreas and intestines at different hours post infection. This study demonstrates that A. veronii is a causative agent associated with massive die-offs of M. rosenbergii and contributes valuable insights into the pathogenesis and host defense mechanisms of A. veronii invasion.

Complete genome sequence and genome-wide transposon mutagenesis enable the determination of genes required for sodium hypochlorite tolerance and drug resistance in pathogen Aeromonas veronii GD2019.

Aeromonas veronii, a significant pathogen in aquatic environments, poses a substantial threat to both human and animal health, particularly in aquaculture. In this study, we isolated A. veronii strain GD2019 from diseased largemouth bass (Micropterus salmoides) during a severe outbreak of aeromonad septicemia in Guangdong Province, China. The complete genome sequence of A. veronii GD2019 revealed that GD2019 contains a single chromosome of 4703,168 bp with an average G+C content of 58.3%. Phylogenetic analyses indicated that GD2019 forms a separate sub-branch in A. veronii and comparative genomic analyses identified the existence of an intact Type III secretion system. Moreover, to investigate the genes that are required for the conditional fitness of A. veronii under various stresses, a high-density transposon insertion library in GD2019 was generated by a Tn5-based transposon and covers 6311 genomic loci including 4155 genes and 2156 intergenic regions. Leveraging this library, 630 genes were classified as essential genes for growth in rich-nutrient LB medium. Furthermore, the genes GE001863/NtrC and GE002550 were found to confer tolerance to sodium hypochlorite in A. veronii. GE002562 and GE002614 were associated with the resistance to carbenicillin. Collectively, our results provide abundant genetic information on A. veronii, shedding light on the pathogenetic mechanisms of Aeromonas.

Comparison of the efficacy of Aeromonas veronii ΔhisJ vaccine in Carassius auratus via different immunization routes.

Introdction: Aeromonas veronii is a significant pathogen to various aquatic life. Infections in fish can lead to high mortality rates, causing substantial economic losses in aquaculture. Vaccination is proposed as a substitute for antibiotics in aquaculture to decrease disease-related mortality and morbidity. Our study previously constructed a hisJ-deleted strain of A. veronii, which provided protective effect to Loach. Methods: To further assess the vaccine's applicability, this study evaluated its genetic stability and safety, and the immune protective effects in Carassius auratus through four distinct administration routes: intraperitoneal injection, intramuscular injection, oral administration, and immersion, to determine the efficacy of these administration routes. Results: The results showed that the vaccine remained genetically stable after 45 generations. Immunization via these administration routes was safe for Carassius auratus, with intraperitoneal and intramuscular injections causing stronger adverse reactions. Immersion immunization resulted in mild adverse reactions, and no significant adverse reactions were observed following oral immunization. Immunizing Carassius auratus at safe concentrations via these routes enhanced the phagocytic activity in serum, increased the levels of non-specific immune-related enzymes (ACP, AKP, C3, C4, LZM, SOD, and IgM), and improved specific serum antibody levels. It also elevated levels of cytokines related to inflammatory responses (IL-1ß, IL-10, TNF-α, TGF-ß) in organ tissues (liver, spleen, kidney, mid-post intestine, and gills). The survival rates of Carassius auratus were measured after challenging with the virulent strain A. veronii TH0426, resulting in the relative survival rates of 64% for Intraperitoneal vaccine group, 56% for Intramuscular vaccine group, 52% for oral vaccine group, and 48% for immersion vaccine group. Analysis of bacterial load in the liver, spleen, and kidney post-challenge showed a decreasing trend in the control group, indicating that the vaccine strain ΔhisJ could gradually restrict the rapid proliferation of bacteria in these tissues, thereby providing a certain level of immune protection against A. veronii. Discussion: In brief, the vaccine strain ΔhisJ can serve as a safe live attenuated vaccine for Carassius auratus, and this study lays the foundation for the development of live attenuated vaccines against Aeromonas veronii.

Expression profiles of four Nile Tilapia innate immune genes during early stages of Aeromonas veronii infection.

OBJECTIVE: During Egypt's hot summer season, Aeromonas veronii infection causes catastrophic mortality on Nile Tilapia Oreochromis niloticus farms. Egypt is ranked first in aquaculture production in Africa, sixth in aquaculture production worldwide, and third in global tilapia production. This study aimed to investigate, at the molecular level, the early innate immune responses of Nile Tilapia to experimental A. veronii infection. METHODS: The relative gene expression, co-expression clustering, and correlation of four selected immune genes were studied by quantitative real-time polymerase chain reaction in four organs (spleen, liver, gills, and intestine) for up to 72 h after a waterborne A. veronii challenge. The four genes studied were nucleotide-binding oligomerization domain 1 (NOD1), lipopolysaccharide-binding protein (LBP), natural killer-lysin (NKL), and interleukin-1 beta (IL-1ß). RESULT: The four genes showed significant transcriptional upregulation in response to infection. At 72 h postchallenge, the highest NOD1 and IL-1ß expression levels were recorded in the spleen, whereas the highest LBP and NKL expression levels were found in the gills. Pairwise distances of the data points and the hierarchical relationship showed that NOD1 clustered with IL-1ß, whereas LBP clustered with NKL; both genes within each cluster showed a significant positive expression correlation. Tissue clustering indicated that the responses of only the gill and intestine exhibited a significant positive correlation. CONCLUSION: The results suggest that NOD1, LBP, NKL, and IL-1ß genes play pivotal roles in the early innate immune response of Nile Tilapia to A. veronii infection, and the postinfection expression profile trends of these genes imply tissue-/organ-specific responses and synchronized co-regulation.

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.

Aeromonas veronii-associated endogenous endophthalmitis: a case report.

BACKGROUND: Aeromonas veronii is a very rare and highly pathogenic microorganism. We investigate the clinical characteristics and significance of endogenous endophthalmitis caused by Aeromonas veronii in our patient. CASE PRESENTATION: A 30-year-old Asian women with systemic lupus erythematosus, uremia, and hypertension developed acute infectious endophthalmitis caused by Aeromonas veronii. After emergency vitrectomy and antibiotic therapy, the clinical condition worsened requiring enucleation. CONCLUSIONS: Aeromonas veronii can cause infection in the human eye, which can manifest as acute endophthalmitis. Early diagnosis and targeted therapy are important for successful treatment.

Polystyrene microplastics promote intestinal colonization of Aeromonas veronii through inducing intestinal microbiota dysbiosis.

The premise that pathogen colonized microplastics (MPs) can promote the spread of pathogens has been widely recognized, however, their role in the colonization of pathogens in a host intestine has not been fully elucidated. Here, we investigated the effect of polystyrene MPs (PS-MPs) on the colonization levels of Aeromonas veronii, a typical aquatic pathogen, in the loach (Misgurnus anguillicaudatus) intestine. Multiple types of MPs were observed to promote the intestinal colonization of A. veronii, among which PS-MPs exhibited the most significant stimulating effect (67.18% increase in A. veronii colonization). PS-MPs inflicted serious damage to the intestinal tracts of loaches and induced intestinal microbiota dysbiosis. The abundance of certain intestinal bacteria with resistance against A. veronii colonization decreased, with Lactococcus sp. showing the strongest colonization resistance (73.64% decline in A. veronii colonization). Fecal microbiota transplantation was performed, which revealed that PS-MPs induced intestinal microbiota dysbiosis was responsible for the increased colonization of A. veronii in the intestine. It was determined that PS-MPs reshaped the intestinal microbiota community to attenuate the colonization resistance against A. veronii colonization, resulting in an elevated intestinal colonization levels of A. veronii.

An Unusual Encounter: Aeromonas veronii Infection in a Case of Ulcerative Colitis.

Aeromonas veronii-associated ulcerative colitis flare is sparsely reported in the literature but is a treatable condition with antibiotics including trimethoprim/sulfamethoxazole (TMP-SMX), fluoroquinolones, and second/third-generation cephalosporins. We report a case of a patient with long-standing ulcerative colitis (UC), who presented with bloody stools, fatigue, and oliguria that did not respond to standard regimen including steroids. The lab finding was significant for leukocytosis and anemia. A. veronii was cultured in the stool specimens. The patient was started on ciprofloxacin with marked improvement of symptoms on the second day of initiation of the antibiotic. Although rare, a possible Aeromonas infection should be suspected in patients presenting with a flare of ulcerative colitis. A prompt initiation of treatment can provide rapid improvement in clinical status of these patients.

Genome-wide DNA N6-methyladenosine in Aeromonas veronii and Helicobacter pylori.

BACKGROUND: DNA N6-methyladenosine (6mA), as an important epigenetic modification, widely exists in bacterial genomes and participates in the regulation of toxicity, antibiotic resistance, and antioxidant. With the continuous development of sequencing technology, more 6mA sites have been identified in bacterial genomes, but few studies have focused on the distribution characteristics of 6mA at the whole-genome level and its association with gene expression and function. RESULTS: This study conducted an in-depth analysis of the 6mA in the genomes of two pathogenic bacteria, Aeromonas veronii and Helicobacter pylori. The results showed that the 6mA was widely distributed in both strains. In A. veronii, 6mA sites were enriched at 3' end of protein-coding genes, exhibiting a certain inhibitory effect on gene expression. Genes with low 6mA density were associated with cell motility. While in H. pylori, 6mA sites were enriched at 5' end of protein-coding genes, potentially enhancing gene expression. Genes with low 6mA density were closely related to defense mechanism. CONCLUSIONS: This study elucidated the distribution characteristics of 6mA in A. veronii and H. pylori, highlighting the effects of 6mA on gene expression and function. These findings provide valuable insights into the epigenetic regulation and functional characteristics of A. veronii and H. pylori.

Identification and Characterization of Immune-Associated MicroRNAs in Silver Carp (Hypophthalmichthys molitrix) Responding to Aeromonas veronii and LPS Stimulation.

The ubiquitous Gram-negative bacterial pathogen Aeromonas veronii (A. veronii) can easily cause inflammatory reactions in aquatic organisms, resulting in high mortality and huge economic losses. MicroRNAs (miRNAs) participate in immune regulation and have certain conserved properties. MiRNAs are involved in the immune responses of a variety of teleost fish infected with bacteria, whereas there is no related report in silver carp (Hypophthalmichthys molitrix). Therefore, we identified the expression profiles of miRNA in silver carp stimulated by A. veronii and LPS. Among them, the quantity of differentially expressed miRNAs (DEmiRNAs) obtained in the silver carp challenge group was 73 (A. veronii) and 90 (LPS). The GO enrichment and analysis of KEGG pathways have shown that the predicted target genes are mainly associated with lipid metabolism and the immune response in silver carp. This indicates the possibility that miRNAs play a role in regulating immune-related pathways. In addition, a total of eight DEmiRNAs validated the accuracy of the sequencing result via quantitative real-time PCR (qRT-PCR). Finally, we selected the silver carp head kidney macrophage cells (HKCs) as model cells and proved that miR-30b-5p can regulate the inflammatory response in silver carp HKCs. This study lays the foundation for exploring miRNA regulation in silver carp during pathogenic bacterial infection. In addition, it provides a reference for the future development of non-coding RNA antibacterial drugs.

Systemic and mucosal immune responses in red tilapia (Oreochromis sp.) following immersion vaccination with a chitosan polymer-based nanovaccine against Aeromonas veronii.

A mucoadhesive chitosan polymer-based nanoplatform has been increasingly recognized as an effective mucosal vaccine delivery system for fish. The present study aimed to investigate the effectiveness of immersion vaccination with a chitosan polymer-based nanovaccine to elicit an immune response in serum and mucus of red tilapia and evaluate its protective efficacy after immersion challenge with a heterogenous strain of Aeromonas veronii UDRT09. Six hundred red tilapia (22 ± 1.8 g) were randomly allocated into four experimental groups: control, empty-polymeric nanoparticle (PC), formalin-killed vaccine (FKV), and chitosan polymer-based nanovaccine (CS-NV) in triplicate. The specific IgM antibody levels and their bactericidal activity were assessed in serum and mucus for 28 days after immersion vaccination and followed by immersion challenge with A. veronii. The immersion vaccine was found to be safe for red tilapia, with no mortalities occurring during the vaccination procedure. The specific IgM antibody levels and bactericidal activity against A. veronii in both serum and mucus were significantly higher in red tilapia vaccinated with CS-NV compared to the FKV and control groups at all time points. Furthermore, the serum lysozyme activity, ACH50, and total Ig levels demonstrated a significant elevation in the groups vaccinated with CS-NV compared to the FKV and control groups. Importantly, the Relative Percentage Survival (RPS) value of the CS-NV group (71 %) was significantly higher than that of the FKV (15.12 %) and PC (2.33 %) groups, respectively. This indicates that the chitosan polymer-based nanovaccine platform is an effective delivery system for the immersion vaccination of tilapia.