Search

Bacterial reverse transcriptase coding gene (RT) is essential for the production of a small satellite DNA‐RNA complex called multicopy single‐stranded DNA (msDNA). In this study, we found a novel retron, retron‐Vmi1 (Vm85) from Vibrio mimicus. The retron is comprised of the msr‐msd region, orf323, and the ret gene, a genetic organization similar to Salmonella's retron‐Sen2 (St85). The protein sequence of the RNA‐directed DNA polymerase (RT‐Vmi1) is highly homologous to the RTs of Vibrio metoecus, Vibrio parahaemolyticus, and Vibrio vulnificus. Phylogenetic and protein sequence similarity analysis of retron‐Vmi1 ORF323 and RT revealed a close relatedness to retron‐Sen2. We found that retron‐Vmi1 was inserted in the dusA gene, similar to the insertion of the retron‐Vpa1 (Vp96) of V. parahaemolyticus AQ3354, suggesting that retrons can be transferred via the tRNA gene. These results are the first convincing evidence that retron is moving across species. The neighboring genes of retron‐Vmi1 shared high homology with the genetic environment of V. parahaemolyticus and V. vulnificus retrons. We also found two junction points within the retron‐Vmi1 and the dusA gene suggesting that retron‐Vmi1 was inserted into this site in a two‐step manner. [ABSTRACT FROM AUTHOR]

We reviewed and analyzed the existing data on vibriosis in Southeast Asia to better understand its burden and prevalent causal agents. We searched PubMed, Web of Science, and EMBASE for studies published between January 2000 and April 2024. A random-effects meta-analysis was used to estimate the pooled isolation rate of non-cholera Vibrio species. Among the 1385 retrieved studies, 22 met the inclusion criteria for the systematic review and 11 were included in the meta-analysis. The pooled isolation rate of non-cholera Vibrio species among diarrheal patients was 5.0 %. Most species that caused vibriosis included V. parahaemolyticus, V. mimicus, V. vulnificus, non-O1/non-O139 V. cholerae, V. fluvialis, and V. alginolyticus. Pooled isolation rate of V. parahaemolyticus and non-O1 V. cholerae were 7.0, and 4.0, respectively. The prevalence of vibriosis in Southeast Asia is non-negligible. Public health strategies should prioritize enhanced surveillance, and clinicians should consider vibriosis in diarrheal patients with seafood consumption history.

HtpG, a bacterial homolog of the eukaryotic 90 kDa heat-shock protein (Hsp90), represents the simplest member of the heat shock protein family. While the significance of Hsp90 in fungal and cancer drug resistance has been confirmed, the role of HtpG in bacterial antibiotic resistance remains largely unexplored. This research aims to investigate the impact of the htpG gene on antibiotic resistance in Vibriomimicus. Through the creation of htpGgene deletion and complementation strains, we have uncovered the essential role of htpG in regulating the structural integrity of the bacterial cell envelope. Our transcriptomics analysis demonstrates that the deletion of htpG increases the sensitivity of V. mimicus to antimicrobial peptides, primarily due to upregulated lipopolysaccharide synthesis, reduced glycerophospholipid content, and weakened efflux pumps activity. Conversely, reduced sensitivity to β-lactam antibiotics in the ΔhtpG strain results from decreased peptidoglycan synthesis and dysregulated peptidoglycan recycling and regulation. Further exploration of specific pathway components is essential for a comprehensive understanding of htpG-mediated resistance mechanisms, aiding in the development of antimicrobial agents. To our knowledge, this is the first effort [ABSTRACT FROM AUTHOR]

Simple Summary: It is known that in highly pathogenic infections, the cAMP receptor protein (CRP) frequently plays an essential regulatory role. A highly pathogenic strain of Vibrio mimicus SCCF01 has been isolated from yellow catfish. To investigate the role of the cAMP receptor protein in regulating SCCF01, we created a strain with a deleted crp gene (Δcrp). The results demonstrated that the expression of genes related to the bacterial type II secretion system, flagellin, adhesion, and metalloproteinase was decreased by the deletion crp gene. The above resulted in modifications to the morphology of the bacteria and colonies, as well as a decrease in the motility, hemolytic activity, biofilm formation, bacterial growth, and enzyme activity. Animal experiments and cytotoxicity analyses verified that crp played a role in V. mimicus pathogenicity. In conclusion, these findings clarified the biological role of the crp gene in V. mimicus, revealed the pathogenic mechanism of the microorganism, and provided a basis for effective control and prevention of V. mimicus infection. Vibrio mimicus is a serious pathogen in aquatic animals, resulting in significant economic losses. The cAMP receptor protein (CRP) often acts as a central regulator in highly pathogenic pathogens. V. mimicus SCCF01 is a highly pathogenic strain isolated from yellow catfish; the crp gene deletion strain (Δcrp) was constructed by natural transformation to determine whether this deletion affects the virulence phenotypes. Their potential molecular connections were revealed by qRT-PCR analysis. Our results showed that the absence of the crp gene resulted in bacterial and colony morphological changes alongside decreases in bacterial growth, hemolytic activity, biofilm formation, enzymatic activity, motility, and cell adhesion. A cell cytotoxicity assay and animal experiments confirmed that crp contributes to V. mimicus pathogenicity, as the LD50 of the Δcrp strain was 73.1-fold lower compared to the WT strain. Moreover, qRT-PCR analysis revealed the inhibition of type II secretion system genes, flagellum genes, adhesion genes, and metalloproteinase genes in the deletion strain. This resulted in the virulence phenotype differences described above. Together, these data demonstrate that the crp gene plays a core regulatory role in V. mimicus virulence and pathogenicity. [ABSTRACT FROM AUTHOR]

Vibrio mimicus caused a seafood-associated outbreak in Florida, USA, in which 4 of 6 case-patients were hospitalized; 1 required intensive care for severe diarrhea. Strains were ctx-negative but carried genes for other virulence determinants (hemolysin, proteases, and types I–IV and VI secretion systems). Cholera toxin–negative bacterial strains can cause cholera-like disease.

Objectives: South Asia remains home to foodborne diseases caused by the Vibrio species. We aimed to compile and update information on the epidemiology of vibriosis in South Asia. Methods: For this systematic review and meta-analysis, we searched PubMed, Web of Science, EMBASE, and Google Scholar for studies related to vibriosis in South Asia published up to May 2023. A random-effects meta-analysis was used to estimate the pooled isolation rate of non–cholera-causing Vibrio species. Results: In total, 38 studies were included. Seven of these were case reports and 22 were included in the meta-analysis. The reported vibriosis cases were caused by non-O1/non-O139 V. cholerae, V. parahaemolyticus, V. fluvialis, and V. vulnificus. The overall pooled isolation rate was 4.0% (95% confidence interval [CI] 3.0-5.0%) in patients with diarrhea. Heterogeneity was high (I2 = 98.0%). The isolation rate of non-O1/non-O139 V. cholerae, V. parahaemolyticus, and V. fluvialis were 9.0 (95% CI 7.0-10.0%), 1.0 (95% CI 1.0-2.0%), and 2.0 (95% CI: 1.0-3.0%), respectively. Regarding V. parahaemolyticus, O3:K6 was the most frequently isolated serotype. Cases peaked during summer. Several studies reported antibiotic-resistant strains and those harboring extended-spectrum beta-lactamases genes. Conclusions: This study demonstrates a high burden of infections caused by non–cholera-causing Vibrio species in South Asia.

Introduction: The pathogenesis of Vibrio mimicus infection in yellow catfish (Pelteobagrus fulvidraco) remains poorly understood, particularly regarding the impact of infection with the pathogen on primary target organs such as the skin and muscle. Methods: In this study, we aim to analyze the pathological intricacies of the skin and muscle of yellow catfish after being infected with V. mimicus using a 1/10 LC50 seven-day post-infection model. Furthermore, we have utilized integrated bioinformatics to comprehensively elucidate the regulatory mechanisms and identify the key regulatory genes implicated in this phenomenon. Results: Our histopathological examination revealed significant pathological changes in the skin and muscle, characterized by necrosis and inflammation. Moreover, tissue remodeling occurred, with perimysium degeneration and lesion invasion into the muscle along the endomysium, accompanied by a transformation of type I collagen into a mixture of type I and type III collagens in the perimysium and muscle bundles. Our eukaryotic transcriptomic and 4D label-free analyses demonstrated a predominantly immune pathway response in both the skin and muscle, with downregulation observed in several cell signaling pathways that focused on focal adhesion-dominated cell signaling pathways. The upregulated genes included interleukins (IL)-1 and -6, chemokines, and matrix metallopeptidases (mmp)-9 and -13, while several genes were significantly downregulated, including col1a and col1a1a. Further analysis revealed that these pathways were differentially regulated, with mmp-9 and mmp-13 acting as the potential core regulators of cytokine and tissue remodeling pathways. Upregulation of NF-kB1 and FOSL-1 induced by IL-17C and Nox 1/2-based NADPH oxidase may have held matrix metallopeptidase and cytokine-related genes. Also, we confirmed these relevant regulatory pathways by qPCR and ELISA in expanded samples. Discussion: Our findings unequivocally illustrate the occurrence of a cytokine storm and tissue remodeling, mediated by interleukins, chemokines, and MMPs, in the surface of yellow catfish infected with V. mimicus. Additionally, we unveil the potential bidirectional regulatory role of MMP-9 and MMP-13. These results provide novel perspectives on the intricate immune response to V. mimicus infection in yellow catfish and highlight potential targets for developing therapies. [ABSTRACT FROM AUTHOR]

Ferric uptake regulator (Fur) is a crucial bacterial regulator that controls the uptake of iron by bacteria, hence influencing their survival and pathogenicity. Vibrio mimicus is an epidemic pathogen that is harmful to aquatic animals and human health, with the characteristics of rapid onset and high mortality after infecting the fish. At present, the function and mechanism of Fur in V. mimicus are still unclear. In this study, the fur gene deletion strain and complementation strain of V. mimicus were constructed. Following fur deletion, proteomic analysis revealed that the abundance of 258 proteins was considerably up-regulated while the abundance of 307 proteins was dramatically down-regulated. The primary roles of these differentially expressed proteins were in a variety of pathways, including virulence, metabolism, enzymes, and so on. Among them, citrate cycle and oxidative phosphorylation were the main pathways affected by Fur. The activities of key enzymes in these two pathways were assessed. The results indicated a decrease in the activities of respiratory chain complexes II and IV, succinate dehydrogenase (SDH), and α-ketoglutarate dehydrogenase (α-KGDH) in the Δ fur strain. Conversely, the activity of isocitrate dehydrogenase (NAD-IDH) was increased. Phenotypic characterization showed that the Δ fur strain exhibited delayed growth, reduced motility, defective biofilm formation, decreased resistance to oxidative stress, increased adhesion, and decreased virulence. Besides, the LD 50 of the Δ fur strain was 31-fold higher than that of the WT strain. These results indicate that Fur serves as an activator for the citrate cycle and oxidative phosphorylation pathway in V. mimicus , and contributing to its virulence. Our findings enhance the understanding of the biological functions of Fur and lay the groundwork for further investigation into the regulatory mechanisms of Fur in V. mimicus. • The fur gene deletion strain and complementation strain of V. mimicus were constructed • Fur can regulate the global metabolism of V. mimicus. • Fur activates Citrate cycle and oxidative phosphorylation pathway in V. mimicus. • Fur contributes to growth, motility, biofilm formation, resistance to oxidative stress, and virulence in V. mimicus. [ABSTRACT FROM AUTHOR]

The alternative sigma factor RpoS functions as a regulator of stress and virulence response in numerous bacterial species. Vibrio mimicus is a critical opportunistic pathogen causing huge losses to aquaculture. However, the exact role of RpoS in V. mimicus remains unclear. In this study, rpoS deletion mutant of V. mimicus was constructed through allelic exchange and the phenotypic and transcriptional changes were investigated to determine the function of RpoS. The abilities of growth, motility, biofilm production, hemolytic activity and pathogenicity were significantly impaired in Δ rpoS strain. Stationary-phase cells of Δ rpoS strain showed lower tolerance to H 2 O 2 , heat, ethanol, and starvation stress than the wild-type strain. Transcriptome analyses revealed the involvement of rpoS in various cellular processes, notably bacterial-type flagellum synthesis and assembly, membrane synthesis and assembly and response to various stimuli. Phenotypic and RNA-seq analysis revealed that RpoS is required for biofilm formation, stress resistance, and pathogenicity in V. mimicus. Furthermore, β-galactosidase activity showed that rpoS is essential for optimal transcription of the flgK , fliA , cheA , mcpH mRNA. These results offer significant insight into the function and regulatory network of rpoS /RpoS, thereby improving our understanding and facilitating selection of molecular targets for future prevention strategies against V. mimicus. [ABSTRACT FROM AUTHOR]

We reviewed and analyzed the existing data on vibriosis in Southeast Asia to better understand its burden and prevalent causal agents. We searched PubMed, Web of Science, and EMBASE for studies published between January 2000 and April 2024. A random-effects meta-analysis was used to estimate the pooled isolation rate of non-cholera Vibrio species. Among the 1385 retrieved studies, 22 met the inclusion criteria for the systematic review and 11 were included in the meta-analysis. The pooled isolation rate of non-cholera Vibrio species among diarrheal patients was 5.0 %. Most species that caused vibriosis included V. parahaemolyticus, V. mimicus, V. vulnificus , non-O1/non-O139 V. cholerae, V. fluvialis, and V. alginolyticus. Pooled isolation rate of V. parahaemolyticus and non-O1 V. cholerae were 7.0, and 4.0, respectively. The prevalence of vibriosis in Southeast Asia is non-negligible. Public health strategies should prioritize enhanced surveillance, and clinicians should consider vibriosis in diarrheal patients with seafood consumption history. [ABSTRACT FROM AUTHOR]

Vibrio mimicus is a bacterium that causes gastroenteritis in humans. This pathogen produces an enterotoxic hemolysin called V. mimicus hemolysin (VMH), which is secreted extracellularly as an inactive 80-kDa protoxin and converted to a 66-kDa mature toxin through cleavage between Arg151 and Ser152. The 56-kDa serine protease termed V. mimicus trypsin-like protease (VmtA) is known to mediate this maturating process. However, some strains including strain ES-20 does not possess the vmtA gene. In the present study, the vmtA-negative strains were found to have a replaced gene that encodes a 43-kDa (403 aa) precursor of a serine protease designated by VmtX (V. mimicus trypsin-like protease X). To examine whether VmtX is also involved in the maturation of VMH, VmtX was isolated from the culture supernatant of V. mimicus strain NRE-20, a metalloprotease-negative mutant constructed from strain ES-20. Concretely, the culture supernatant was fractionated with 70% saturated ammonium sulfate and subjected to affinity column chromatography using a HiTrap Benzamidine FF column. The analysis of the N-terminal amino acid sequences of the proteins in the obtained VmtX preparation indicated that the 39-kDa protein was active VmtX consisting of 371 aa (Ile33-Ser403). The VmtX preparation was found to activate pro-VMH through generation of the 66-kDa protein. Additionally, treatment of the VmtX preparation with serine protease inhibitors, such as leupeptin and phenylmethylsulfonyl fluoride, significantly suppressed the activities to hydrolyze the specific peptide substrate and to synthesize the 66-kDa toxin. These findings indicate that VmtX is the second protease that mediats the maturation of VMH. [ABSTRACT FROM AUTHOR]

Vibrio mimicus is a global causative agent of vibriosis in a variety of aquatic animals and causes major economic losses to aquaculture. It could survive in water for extended periods of time under environmental stress, but its survival strategy remains unknow. This study described the survival, virulent and gene expression changes of V. mimicus cells undergoing starvation stress. After 4 weeks’ cultivation in media without nutrients, V. mimicus Y4 showed reduced rates of activity with marked changes in morphology and physiological activities. The culturable cell counts declined gradually to 104 CFU/mL and the shape changed from rod-shaped to coccoid with short rods or spherical. The motility of starved cells decreased after starvation and the biofilm production was significantly lower than wild cells. The starved cells still produced β-hemolysis, lecithinase and caseinase, but its infectivity to Macrobrachium nipponense was weakened. To investigate the mechanism behind morphological and physiological changes, we further analyzed differently expressed genes (DEGs) between starved and wild cells at the whole transcriptional level. The RNA-seq analysis demonstrated that large-scale DEGs were involved in transferase, membrane, dehydrogenase, synthase, flagellar, hemolysin, pilus assembly, and starvation, etc. Among them, the well-known virulence-related genes were downregulated significantly, including vmh, pilA, vipA, capB, tadC, huvX, ompA, etc. These data provide a key resource to understand the regulatory mechanisms of V. mimicus to starvation stress.

Infection with Vibrio mimicus in the Siluriformes has demonstrated a rapid and high infectivity and mortality rate, distinct from other hosts. Our earlier investigations identified necrosis, an inflammatory storm, and tissue remodeling as crucial pathological responses in yellow catfish (Pelteobagrus fulvidraco) infected with V. mimicus. The objective of this study was to further elucidate the impact linking these pathological responses within the host during V. mimicus infection. Employing metabolomics and transcriptomics, we uncovered infection-induced dense vacuolization of perimysium; Several genes related to nucleosidase and peptidase activities were significantly upregulated in the skin and muscles of infected fish. Concurrently, the translation processes of host cells were impaired. Further investigation revealed that V. mimicus completes its infection process by enhancing its metabolism, including the utilization of oligopeptides and nucleotides. The high susceptibility of yellow catfish to V. mimicus infection was associated with the composition of its body surface, which provided a microenvironment rich in various nucleotides such as dIMP, dAMP, deoxyguanosine, and ADP, in addition to several amino acids and peptides. Some of these metabolites significantly boost V. mimicus growth and motility, thus influencing its biological functions. Furthermore, we uncovered an elevated expression of gangliosides on the surface of yellow catfish, aiding V. mimicus adhesion and increasing its infection risk. Notably, we observed that the skin and muscles of yellow catfish were deficient in over 25 polyunsaturated fatty acids, such as Eicosapentaenoic acid, 12-oxo-ETE, and 13-Oxo-ODE. These substances play a role in anti-inflammatory mechanisms, possibly contributing to the immune dysregulation observed in yellow catfish. In summary, our study reveals a host immune deviation phenomenon that promotes bacterial colonization by increasing nutrient supply. It underscores the crucial factors rendering yellow catfish highly susceptible to V. mimicus , indicating that host nutritional sources not only enable the establishment and maintenance of infection within the host but also aid bacterial survival under immune pressure, ultimately completing its lifecycle. • The research offered fresh insights into the pathogenesis of Vibrio mimicus in the yellow catfish host. • V. mimicus completes infection by enhancing metabolism, utilizing oligopeptides and nucleotides. • Yellow catfish body surface, rich in nucleotides, amino acids, and peptides, affects V. mimicus growth and motility. • Yellow catfish displayed deficiency in polyunsaturated fatty acids, impacting anti-inflammatory mechanisms. [ABSTRACT FROM AUTHOR]

Protein lysine acetylation is an evolutionarily conserved post-translational modification (PTM), which is dynamic and reversible, playing a crucial regulatory role in almost every aspect of metabolism, of both eukaryotes and prokaryotes. Several global lysine acetylome studies have been carried out in various bacteria, but thus far, there have been no reports of lysine acetylation for the commercially important aquatic animal pathogen Vibrio mimicus. In the present study, we used anti-Ac-K antibody beads to highly sensitive immune-affinity purification and combined high-resolution LC-MS/MS to perform the first global lysine acetylome analysis in V. mimicus , leading to the identification of 1,097 lysine-acetylated sites on 582 proteins, and more than half (58.4%) of the acetylated proteins had only one site. The analysis of acetylated modified peptide motifs revealed six significantly enriched motifs, namely, KacL, KacR, L(-2) KacL, LKacK, L(-7) EKac, and IEKac. In addition, bioinformatic assessments state clearly that acetylated proteins have a hand in many important biological processes in V. mimicus , such as purine metabolism, ribosome, pyruvate metabolism, glycolysis/gluconeogenesis, the TCA cycle, and so on. Moreover, 13 acetylated proteins were related to the virulence of V. mimicus. To sum up, this is a comprehensive analysis whole situation protein lysine acetylome in V. mimicus and provides an important foundation for in-depth study of the biological function of lysine acetylation in V. mimicus. [ABSTRACT FROM AUTHOR]

Vibrio mimicus is a foodborne pathogen, which is widely distributed in the aquatic environment. Moreover, it is often involved in aquatic animal diseases. In recent years, V. mimicus is an emerging pathogen in some species of Siluriformes. The strain SCCF01 was isolated from yellow catfish (Pelteobagrus fulvidraco). In this study, we aimed to perform genomic analysis of V. mimicus strain SCCF01 to identify genetic features and evolutionary relationships. Information on gene function and classification was obtained by functional annotation, and circular graph of strain SCCF01 genome, which was created by Circos v0.64. Information on virulence genes (adhesion, flagellum system, exotoxin, and secretory system, etc.) was obtained by virulence genes annotation. Genome element prediction showed that most of the mobile elements were distributed in chromosome I. Therefore, chromosome I of SCCF01 genome has more plasticity than chromosome II and might be larger in size. Genomic linear relationship between the strain of V. mimicus and strain SCCF01 was analyzed by linear pairwise comparison but was unable to determine the relationship. Gene family analysis predicted that the evolutionary direction of strain SCCF01 was: clinical strain → environmental strain → SCCF01 strain. Phylogenetic analysis showed that the strain SCCF01 was more closely related to environmental strains. According to gene family analysis and phylogenetic analysis, we speculated that strain SCCF01 has probably diverged from environmental strains.

Protein lysine acetylation is an evolutionarily conserved post-translational modification (PTM), which is dynamic and reversible, playing a crucial regulatory role in almost every aspect of metabolism, of both eukaryotes and prokaryotes. Several global lysine acetylome studies have been carried out in various bacteria, but thus far, there have been no reports of lysine acetylation for the commercially important aquatic animal pathogen Vibrio mimicus. In the present study, we used anti-Ac-K antibody beads to highly sensitive immune-affinity purification and combined high-resolution LC-MS/MS to perform the first global lysine acetylome analysis in V. mimicus, leading to the identification of 1,097 lysine-acetylated sites on 582 proteins, and more than half (58.4%) of the acetylated proteins had only one site. The analysis of acetylated modified peptide motifs revealed six significantly enriched motifs, namely, KacL, KacR, L(-2) KacL, LKacK, L(-7) EKac, and IEKac. In addition, bioinformatic assessments state clearly that acetylated proteins have a hand in many important biological processes in V. mimicus, such as purine metabolism, ribosome, pyruvate metabolism, glycolysis/gluconeogenesis, the TCA cycle, and so on. Moreover, 13 acetylated proteins were related to the virulence of V. mimicus. To sum up, this is a comprehensive analysis whole situation protein lysine acetylome in V. mimicus and provides an important foundation for in-depth study of the biological function of lysine acetylation in V. mimicus.

This document is a corrigendum for an article titled "Transcriptome reveals the role of the htpG gene in mediating antibiotic resistance through cell envelope modulation in Vibrio mimicus SCCF01." The corrigendum addresses an error in the funding statement of the original article. The correct funding statement is provided, and the authors apologize for the error, stating that it does not affect the scientific conclusions of the article. [Extracted from the article]

The outer membrane protein U (OmpU) is a conserved outer membrane protein in a variety of pathogenic Vibrio species and has been considered as a vital protective antigen for vaccine development. Vibrio mimicus (V. mimicus) is the pathogen causing ascites disease in aquatic animals. In this study, the prokaryotically expressed and purified His-tagged OmpU of V. mimicus (His-OmpU) was used as a subunit vaccine. The formalin inactivated V. mimicus , purified His tag (His-tag), and PBS were used as controls. The vaccinated yellow catfish were challenged with V. mimicus at 28 days post-vaccination, and the results showed that the His-OmpU and inactivated V. mimicus groups exhibited much higher survival rates than the His-tag and PBS groups. To fully understand the underlying mechanism, we detected the expression levels of several immune-related genes in the spleen of fish at 28 days post-vaccination and 24 h post-challenge. The results showed that most of the detected immune-related genes were significantly upregulated in His-OmpU and inactivated V. mimicus groups. In addition, we performed the serum bactericidal activity assay, and the results showed that the serum from His-OmpU and inactivated V. mimicus groups exhibited much stronger bactericidal activity against V. mimicus than those of His-tag and PBS groups. Finally, the serum agglutination antibody was detected, and the antibody could be detected in His-OmpU and inactivated V. mimicus groups with the antibody titers increasing along with the time post-vaccination, but not in His-tag or PBS group. Our data reveal that the recombinant OmpU elicits potent protective immune response and is an effective vaccine candidate against V. mimicus in yellow catfish. • Successfully constructed a prokaryotic expression plasmid and purified OmpU recombinant protein. • The OmpU subunit vaccine induced a strong immune protection in yellow catfish. • The OmpU subunit vaccine induced high serum antibody titer agasinst V. mimicus. [ABSTRACT FROM AUTHOR]

In 2018, a severe disease characterized by serious and shaped ulcers in the skins were broke out in the main culture area of yellow catfish (Pelteobagrus fulvidraco) in Zhejiang Province. In order to elucidate the characterization of the causative agent and analyze virulence factors and antimicrobial susceptibility of the pathogen, several bacterial strains were isolated from the lesions and visceral organs of diseased fish. These isolates were subjected to physiology and biochemistry characteristics analyses by using bacterial biochemical identification instrument and biochemical identification micro-tubes. For molecular identification, the 16S rRNA and pyrH were amplified by PCR and compared with sequences deposited in databases, and molecular phylogenetic trees were constructed. Based on the morphological characteristics, phenotypic characteristics, 16S rRNA and pyrH gene sequence analysis, the 11 predominant bacterial strains were identified as Vibrio mimicus. Challenge trials were conducted by intraperitoneal injection, and the results showed that the two representative isolates exhibited high virulence in yellow catfish, skin ulcers occurred in both changed group. The potential virulence of the V. mimicus isolates were examined by phenotypic and PCR assays. All the studied strains exhibited hemolytic activity, and were positive for extracellular protease and gelatinase and DNA degrading activity, but negative for lecithinase activity. Siderophore activity were observed in all V. mimicus isolates. The vmh, ompU and toxR genes were found in all the isolated V. mimicus, whereas none possessed the tcpA, ctxA, st, zot, ace or tdh gene. Antimicrobial susceptibility of the isolated V. mimicus were determined by trace double dilution method and the results showed that the isolates were resistant to ampicillin, sulfadiazine, sulfamethoxazole, sulfamonomethoxine, were sensitive to ciprofloxacin, enrofloxacin, florfenicol, doxycycline, oxytetracycline, thiamphenicol, erythromycin thiocyanate, josamycin, sulfamethoxine, while resistance to neomycin sulphate and thiamphenicol were found in two isolates. Therefore, our study demonstrated the virulence of V. mimicus in yellow catfish as the causative agent of the enzootic. The isolated V. mimicus exhibited the same phenotypic traits and virulence-related genotype, also the biochemical characteristics and antibiotic resistance profile were similar, indicating that they had the same genetic background or source of infection. [ABSTRACT FROM AUTHOR]

Vibrio mimicus is a pathogenic bacterium that cause red body disease in Macrobrachium nipponense , leading to high mortality and financial loss. Based on previous studies, rpoS gene contribute to bacterial pathogenicity during infection, but the role of RpoS involved in the immune response of M. nipponense under V. mimicus infection remains unclear. In this study, the pathogen load and the RNA-seq of M. nipponense under wild-type and Δ rpoS strain V. mimicus infection were investigated. Over the entire infection period, the Δ rpoS strain pathogen load was always lower than that of the wild-type strain in the M. nipponense hemolymph, hepatopancreas, gill and muscle. Furthermore, the expression level of rpoS gene in the hepatopancreas was the highest at 24 hours post infection (hpi), then the samples of hepatopancreas tissue infected with the wild type and Δ rpoS strain at 24 hpi were selected for RNA-seq sequencing. The results revealed a significant change in the transcriptomes of the hepatopancreases infected with Δ rpoS strain. In contrast to the wild-type infected group, the Δ rpoS strain infected group exhibited differentially expressed genes (DEGs) enriched in 181 KEGG pathways at 24 hpi. Among these pathways, 8 immune system-related pathways were enriched, including ECM-receptor interaction, PI3K-Akt signaling pathway, Rap1 signaling pathway, Gap junction, and Focal adhesion, etc. Among these pathways, up-regulated genes related to Kazal-type serine protease inhibitors, S-antigen protein, copper zinc superoxide dismutase, tight junction protein, etc. were enriched. This study elucidates that rpoS can affect tissue bacterial load and immune-related pathways, thereby impacting the survival rate of M. nipponense under V. mimicus infection. These findings validate the potential of rpoS as a promising target for the development of a live attenuated vaccine against V. mimicus. • The mutant of rpoS gene can reduce the pathogen load in M. nipponense tissues.. • RpoS is crucial in M. nipponense immune response to V. mimicus.. • Targeting rpoS gene can enhance M. nipponense survival against V. mimicus infection.. [ABSTRACT FROM AUTHOR]

Vibrio mimicus (V. mimicus) is a significant pathogen in freshwater catfish, though knowledge of virulence determinants and effective vaccine is lacking. Multiplex genome editing by natural transformation (MuGENT) is an easy knockout method, which has successfully used in various bacteria except for V. mimicus. Here, we found V. mimicus strain SCCF01 can uptake exogenous DNA and insert it into genome by natural transformation assay. Subsequently, we exploited this property to make five mutants (△Hem, △TS1, △TS2, △TS1△TS2, and △II), and removed the antibiotic resistance marker by Flp-recombination. Finally, all of the mutants were identified by PCR and RT-PCR. The results showed that combination of natural transformation and FLP-recombination can be applied successfully to generate targeted gene disruptions without the antibiotic resistance marker in V. mimicus. In addition, the five mutants showed mutant could be inherited after several subcultures and a 668-fold decrease in the virulence to yellow catfish (Pelteobagrus fulvidraco). This study provides a convenient method for the genetic manipulation of V. mimicus. It will facilitate the identification and characterization of V. mimicus virulence factors and eventually contribute to a better understanding of V. mimicus pathogenicity and development of attenuated vaccine. • Natural transformation occurred in Vibrio mimicus. • Natural transformation is a rapid method to create genetic deletions in V. mimicus. • Natural transformation holds potential in the development of attenuated vaccine. [ABSTRACT FROM AUTHOR]

Abstract Vibrio mimicus (V. mimicus) is an enteric pathogen causing serious vibriosis in aquatic animals, and intestinal mucosal immunity elicited by oral DNA vaccines plays a vital role in the resistance to the pathogen. Yet, the immunogenicity of oral naked DNA vaccine is poor due to the degradation in the digestive tract. Therefore, it is necessary to use targeted DNA delivery strategy for improving the potency of vaccine. In our previous studies, the epitopes of OmpU and VMH proteins from V. mimicus have been identified. Here, a double-targeted DNA vaccine based on the multi-epitope peptide (named OVepis) of V. mimicus was developed by using E. coli DH5α bacterial ghosts (BGs) and invariant chain-like protein (Iclp) of grass carps as exogenous and endogenous targeting delivery carriers, respectively, and then the efficacy was evaluated in grass carps via oral gavage administration. The results showed that the loading efficiency and capacity of DH5α-BGs to pcDNA3.1-Iclp-OVepis were 89.91% and 16.6 μg per milligram BGs, respectively. DH5α-BGs loaded with pcDNA3.1-Iclp-OVepis targeted efficiently RAW264.7 cells and mediated effective gene expression. Higher transcription levels of the Iclp-OVepis gene were detectable in the different tissues of fish in the double-targeted DNA vaccine (DH5α-BGs/pcDNA3.1-Iclp-OVepis) group than that in the endogenous-targeted DNA vaccine (pcDNA3.1-Iclp-OVepis) group at 21 dpv. The double-targeted DNA vaccine significantly enhanced SOD activity, LZM activity and C3 contents in the serum and intestinal mucus of immunized fish. Specific antibody levels in the serum and intestinal mucus were markedly increased in the double-targeted DNA vaccine group compared to the other DNA vaccine groups. at each examined time point. Likewise, the proliferative activities of peripheral blood and intestinal intraepithelial lymphocytes of fish in the double-targeted DNA vaccine group were also significantly higher at 28 dpv. Importantly, the vaccine conferred high protection against V. mimicus challenge with 81.11% RPS. This study suggested that the oral double-targeted DNA vaccine might be used as a promising vaccine candidate to control V. mimicus infection. Highlights • An oral double-targeted DNA vaccine of V. mimicus was developed and evaluated in grass carps. • The double-targeted DNA vaccine elicited strong systemic and intestinal mucosal immune responses. • The double-targeted DNA vaccine conferred a good protection against V. mimicus challenge with 81.11% RPS. • The double-targeted strategy may provide useful information for designing oral vaccine in aquaculture. [ABSTRACT FROM AUTHOR]

Atypical El Tor strains of Vibrio cholerae O1 harboring variant ctxB genes of cholera toxin (CT) are gradually becoming a major cause of recent cholera epidemics. Vibrio mimicus occasionally produces CT, encoded by ctxAB on CTX? genome; and toxin-coregulated pilus (TCP), a major intestinal colonization factor and also the CTX?-specific receptor. This study carried out extensive molecular characterization of CTX? and ToxT regulon in ctx+ve strains of V. mimicus isolated from the Bengal coast. Southern hybridization, PCR, and DNA sequencing of virulence related-genes revealed the presence of an El Tor type CTX prophage (CTXET) carrying a novel ctxAB, tandem copies of environmental type pre-CTX prophage (pre-CTXEnv), and RS1 elements, which were organized in an array of RS1-CTXET -RS1-pre- CTXEnv-pre-CTXEnv. Additionally, a novel variant of tcpA and toxT respectively, showing phylogenetic lineage to a clade of V. cholerae non-O1/O139, was identified. The V. mimicus strains lacked the RTX and TLC elements, and Vibrio seventh pandemic islands of the El Tor strains, but contained five heptamer (TTTTGAT) repeats in ctxAB promoter region like some classical strains of V. cholerae O1. PFGE analysis showed all the ctx+ve V. mimicus strains were clonally related. However, their in vitro CT production and in vivo toxigenecity were variable, which could be explained by differential transcription of virulence genes along with ToxR regulon. Taken together, our findings strongly suggest that environmental V. mimicus strains act as potential reservoir of atypical virulence factors, including variant CT and ToxT regulon, and may contribute to the evolution of V. cholerae hybrid strains. [ABSTRACT FROM AUTHOR]

Vibrio mimicus ( V. mimicus ) is an important bacterial pathogen causing high mortality rates for fish and shellfish species. Prevention of vibriosis still remains a challenge, and an efficacious and safe vaccine that confers protection against V. mimicus needs to be developed. Here, with the purpose of generating V. mimicus bacterial ghosts (VmBGs), the bacteriophage PhiX174 lysis gene E was cloned into the shuttle plasmid pBV220 for construction of the recombinant temperature-sensitive lysis plasmid pBV220-lysisE. The pBV220-lysisE was then electroporated into V. mimicus strain 04–14, and the resultant transformants were used for production of VmBGs by inducing lysis gene E expression. The VmBGs were characterized by observing their morphology and structure on electron microscopy, and then the safety and vaccine potential of VmBGs were further evaluated in grass carps ( Ctenopharyngodon idella ), The results showed that the efficiency of VmBGs induction was about 99.91%, and no living bacteria survived after lyophilization. The obvious transmembrane lysis pores with loss of cytoplasmic materials were observed in VmBGs by electron microscopy. Fish vaccinated with VmBGs via intraperitoneal route showed significantly up-regulated expression of several immune-related genes (G-type lysozyme, IL-1β, MHC-I and MHC-IIβ) in the spleens, and higher serum agglutinating antibody level, serum bactericidal activity as well as peripheral blood lymphocytes proliferation responses compared to formalin-killed cells of V. mimicus (FKC) vaccinated fish and PBS control fish. More importantly, strong protection with relative survival rate of 76.67% was recorded in the VmBGs-vaccinated fish after challenge with V. mimicus strain 04–14, whereas the FKC vaccine and PBS control showed 40% and 0% survival rate, respectively. Overall, these findings suggest that the newly constructed VmBGs may be used as a promising vaccine candidate for the control of V. mimicus infection in fish. [ABSTRACT FROM AUTHOR]

Vibrio mimicus (V. mimicus) is known to cause severe bacterial diseases with high mortality rates in fish, resulting in significant economic losses in the global aquaculture industry. Therefore, the objective of this study was to develop a safe and effective vaccine for protecting Carassius auratus (C. auratus) against V. mimicus infection. Recombinant Lactobacillus casei (L. casei) strains, Lc-pPG-612-OmpU and Lc-pPG-612-OmpU-CTB (surface-displayed), were constructed using a L. casei strain (ATCC 393) as an antigen delivery carrier and the cholera toxin B subunit (CTB) as an adjuvant. The two recombinant strains of L. casei were administered to C. auratus via oral immunization, and the protective efficacy of the oral vaccines was assessed. The results demonstrated that oral immunization with the two strains significantly increased the levels of nonspecific immune indicators in C. auratus , including alkaline phosphatase (AKP), lysozyme (LYS), acid phosphatase (ACP), complement 3 (C3), complement 4 (C4), lectin, and superoxide dismutase (SOD). Moreover, the experiment groups exhibited significant increases in specific immunoglobulin M (IgM) antibodies against OmpU, as well as the transcription of immune-related genes (ie., IL-1β, TNF-α, IL-10, and TGF-β), when compared to the control groups. Following infection of C. auratus with V. mimicus , the mortality rate of the recombinant L. casei -treated fish was observed to be lower compared to the control group. This finding suggests that recombinant L. casei demonstrates effective protection against V. mimicus infection in C. auratus. Furthermore, the addition of the immune adjuvant CTB was found to induce a more robust adaptive and innate immune response in C. auratus , resulting in reduced mortality after infection with V. mimicus. • Two recombinant L. casei strains expressing OmpU and OmpU-CTB proteins were successfully constructed. • After oral immunization of C. auratus with the two recombinant L. casei strains, innate and adaptive immunity were enhanced. • The immunity and survival rate of C. auratus after the injection of V. mimicus were better in the Lc-pPG-612-OmpU-CTB group. • The strain Lc-pPG-612-OmpU-CTB is a promising oral vaccine to protect C. auratus against V. mimicus infection. [ABSTRACT FROM AUTHOR]

The current study determines the density of Vibrio spp. and isolates V. cholerae and Vibrio mimicus from fish-anatomical-sites, prawn, crab and mussel samples recovered from fish markets, freshwater and brackish water. Virulence and antibiotic resistance profiling of isolates were carried out using standard molecular and microbiology techniques. Vibrio spp. was detected in more than 90% of samples [134/144] and its density was significantly more in fish than in other samples. Vibrio. cholerae and V. mimicus were isolated in at least one sample of each sample type with higher isolation frequency in fish samples. All the V. cholerae isolates belong to non-O1/non-O139 serogroup. One or more V. cholerae isolates exhibited intermediate or resistance against each of the eighteen panels of antibiotics used but 100% of the V. mimicus were susceptible to amikacin, gentamycin and chloramphenicol. Vibrio cholerae exhibited relatively high resistance against polymyxin, ampicillin and amoxicillin/clavulanate while V. mimicus isolates exhibited relatively high resistance against nitrofurantoin, ampicillin and polymixin. The multiple-antibiotic-resistance-index [MARI] for isolates ranges between 0 and 0.67 and 48% of the isolates have MARI that is >0.2 while 55% of the isolates exhibit MultiDrug Resistance Phenotypes. The percentage detection of acc, ant, drf18, sul1, mcr-1, blasvh, blaoxa, blatem, blaoxa48, gyrA, gyrB and parC resistance-associated genes were 2%, 9%, 14%, 7%, 2%, 25%, 7%, 2%, 2%, 32%, 25% and 27% respectively while that for virulence-associated genes in increasing other was ace [2%], tcp [11%], vpi [16%], ompU [34%], toxR [43%], rtxC [70%], rtxA [73%] and hyla [77%]. The study confirmed the potential of environmental non-O1/non-O139 V. cholerae and V. mimicus to cause cholera-like infection and other vibriosis which could be difficult to manage with commonly recommended antibiotics. Thus, regular monitoring of the environment to create necessary awareness for this kind of pathogens is important in the interest of public health., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Abioye et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

RESUMO: As bactérias do gênero Vibrio habitam ambiente tipicamente marinho e estuarino, sendo comumente isoladas de pescados. As principais espécies de Vibrio reportadas como agentes de infecções em humanos são V. vulnificus , V. parahaemolyticus , V. cholerae e V. mimicus . V. vulnificus é considerado o mais perigoso, podendo causar septicemia e levar à morte. V. parahaemolyticus é um patógeno importante nas regiões costeiras de clima temperado e tropical em todo o mundo e tem sido responsável por casos de gastroenterites associadas ao consumo de peixes, moluscos e crustáceos marinhos. V. cholerae causa surtos, epidemias e pandemias relacionados com ambientes estuarinos. V. mimicus pode causar episódios esporádicos de gastroenterite aguda e infecções de ouvido. A patogenicidade das bactérias está ligada à habilidade do micro-organismo em iniciar uma doença (incluindo entrada, colonização e multiplicação no corpo humano). Para que isso ocorra, os micro-organismos fazem uso de diversos fatores. O objetivo desta revisão foi sintetizar o conhecimento disponível na literatura sobre os fatores de patogenicidade de V. vulnificus , V. parahaemolyticus , V. cholerae e V. mimicus .

Vibrio mimicus (V. mimicus) is a pathogenic bacterium that causes diseases in humans and various aquatic animals. A particularly efficient way to provide protection against V. mimicus is through vaccination. However, there are few commercial vaccines against V. mimics , especially oral vaccines. In our study, two surface-display recombinant Lactobacillus casei (L. casei) Lc-pPG-OmpK and Lc-pPG-OmpK-CTB were constructed using L. casei ATCC393 as an antigen delivery vector, outer membrane protein K (OmpK) of V. mimicus as an antigen, and cholera toxin B subunit (CTB) as a molecular adjuvant; furthermore, the immunological effects of recombinant L.casei in Carassius auratus (C. auratus) were assessed. The results indicated that oral recombinant L.casei Lc-pPG-OmpK and Lc-pPG-OmpK-CTB stimulated higher levels of serum-specific immunoglobulin M (IgM) and increased the activity of acid phosphatase (ACP), alkaline phosphatase (AKP), superoxide dismutase (SOD), lysozyme (LYS), lectin, C3, and C4 in C. auratus , compared with control groups (Lc-pPG group and PBS group). Furthermore, the expression of interleukin-1β (IL-1β), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), and transforming growth factor-β (TGF-β) in the liver, spleen, head kidney, hind intestine and gills of C. auratus was significantly increased, compared with that in the controls. These results demonstrated that the two recombinant L. casei strains could effectively trigger humoral and cellular immunity in C. auratus. In addition, two recombinant L.casei strains were able to survive and colonize the intestine of C. auratus. Importantly, after being challenged with V. mimicus , C. auratus fed Lc-pPG-OmpK and Lc-pPG-OmpK-CTB exhibited greater survival rates than the controls (52.08% and 58.33%, respectively). The data showed that recombinant L. casei could elicit a protective immunological response in C. auratus. The effect of the Lc-pPG-OmpK-CTB group was better than that of the Lc-pPG-OmpK group, and Lc-pPG-OmpK-CTB was found to be an effective candidate for oral vaccination. • Two surface-displayed recombinant L. casei strains expressing OmpK and OmpK-CTB were successfully constructed. • Oral administration of L. casei to C. auratus can enhance its humoral and cellular immunity. • Recombinant L. casei can colonize the intestine and protect C. auratus from V. mimicus infection. • Recombinant L. casei fused with molecular adjuvant CTB showed better immune effects in C. auratus than recombinant L. casei expressing a single antigen. [ABSTRACT FROM AUTHOR]

New aquafeed ingredients produced by a circular economy approach are the opportunity for sustainable and resilient aquaculture. In the light of this approach, the mixture of abalone waste and Sargassum spp (9:1) fermented by Saccharomyces cereviceae and Lactobacillus casei (Yakult®) (FMAS) were used to replace 0% (FMAS0), 25% (FMAS-25), 50% (FMAS-50), 75% (FMAS-75), and 100% (FMAS-100) of fishmeal (FM) protein in marron, Cherax cainii diet. The marron was fed these diets in triplicate for 90 days. Growth, feed utilization and protein efficiency ratio were unchanged in marron-fed all test diets. Improvement in apparent protein digestibility was aligned with an increase in the size and number of B-cells in the hepatopancreas. Most of the immune responses, except for haemocyte clotting time, hyaline cells and neutral red retention time (NRR time) were unchanged by 42- and 90-days feeding trials compared to those of the control group. 90 days post-feeding marron with FMAS25 showed a lower haemocyte clotting time than the post 42 days feeding marron with the same diet. Hyaline cells increased in marron fed FMAS75 for 90 days compared to marron fed the same diet for 42 days. The challenge test involved injecting marron with Vibrio mimicus resulted in a 100% survival rate after 96 h of exposure. During the challenge test, phagocytosis activity in 24 and 48-h post-challenged marron fed FMAS75 decreased which recovered after 96 h post-challenge. Marron fed FMAS50 also recorded a significantly higher proportion of granular cells after 24 h and NRR time at 96 h compared with that of other treatments. Given the above indicators of bio-growth, feed efficiency and immune responses, total replacement of FM protein of marron practical feed with FMAS are considered feasible and optimum to maintain health status and resistance to disease., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Vibrio mimicus is the causative agent of ascites disease in fish. The heat-labile hemolytic toxin designated VMH is an immunoprotective antigen of V. mimicus . However, its epitopes have not been well characterized. Here, a commercially available phage displayed 12-mer peptide library was used to screen epitopes of VMH protein using polyclonal rabbit anti-rVMH protein antibodies, and then five positive phage clones were identified by sandwich and competitive ELISA. Sequences analysis showed that the motif of DPTLL displayed on phage clone 15 and the consensus motif of SLDDDST displayed on the clone 4/11 corresponded to the residues 134–138 and 238–244 of VMH protein, respectively, and the synthetic motif peptides could also be recognized by anti-rVMH-HD antibody in peptide-ELISA. Thus, both motifs DPTLL and SLDDDST were identified as minimal linear B-cell epitopes of VMH protein. Although no similarity was found between VMH protein and the consensus motif of ADGLVPR displayed on the clone 2/6, the synthetic peptide ADGLVPR could absorb anti-rVMH-HD antibody and inhibit the antibody binding to rVMH protein in enhanced chemoluminescence Western blotting, whereas irrelevant control peptide did not affect the antibody binding with rVMH. These results revealed that the peptide ADGLVPR was a mimotope of VMH protein. Taken together, three novel B-cell epitopes of VMH protein were identified, which provide a foundation for developing epitope-based vaccine against V. mimicus infection in fish. [ABSTRACT FROM AUTHOR]

Vibrio mimicus is an estuarine bacterium, while it can cause severe diarrhea, wound infection, and otitis media in humans. This pathogen secretes a relatively important toxin named V. mimicus metalloprotease (VMP). In this study, we clarified regulation of the VMP production according to the quorum-sensing master regulatory protein named LuxR. First, the full length of luxR gene, encoding LuxR, was detected in V. mimicus strain E-37, an environmental isolate. Next, the putative consensus binding sequence of LuxR protein could be detected in the upstream (promoter) region of VMP encoding gene, vmp. Finally, the effect of disruption of luxR gene on the expression of vmp and production of VMP was evaluated. Namely, the expression of vmp was significantly diminished by luxR disruption and the production of VMP was severely altered. Taken together, here we report that VMP production is under the positive regulation of the quorum-sensing master regulatory protein, LuxR. [ABSTRACT FROM AUTHOR]