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Virulence 2015
Topics: Aeromonas hydrophila; Animals; Deoxyribonucleases; Female; Fishes; Gram-Negative Bacterial Infections; Virulence Factors
PubMed: 26055576
DOI: 10.1080/21505594.2015.1058479 -
Vaccines Oct 2023The application of nanotechnology in aquaculture for developing efficient vaccines has shown great potential in recent years. Nanovaccination, which involves... (Review)
Review
The application of nanotechnology in aquaculture for developing efficient vaccines has shown great potential in recent years. Nanovaccination, which involves encapsulating antigens of fish pathogens in various polymeric materials and nanoparticles, can afford protection to the antigens and a sustained release of the molecule. Oral administration of nanoparticles would be a convenient and cost-effective method for delivering vaccines in aquaculture while eliminating the need for stressful, labour-intensive injectables. The small size of nanoparticles allows them to overcome the degradative digestive enzymes and help deliver antigens to the target site of the fish more effectively. This targeted-delivery approach would help trigger cellular and humoral immune responses more efficiently, thereby enhancing the protective efficacy of vaccines. This is particularly relevant for combating diseases caused by pathogens like , a major fish pathogen responsible for significant morbidity and mortality in the aquaculture sector. While the use of nanoparticle-based vaccines in aquaculture has shown promise, concerns exist about the potential toxicity associated with certain types of nanoparticles. Some nanoparticles have been found to exhibit varying degrees of toxicity, and their safety profiles need to be thoroughly assessed before widespread application. The introduction of nanovaccines has opened new vistas for improving aquaculture healthcare, but must be evaluated for potential toxicity before aquaculture applications. Details of nanovaccines and their mode of action, with a focus on protecting fish from infections and outbreaks caused by the ubiquitous opportunistic pathogen , are reviewed here.
PubMed: 37896958
DOI: 10.3390/vaccines11101555 -
Microorganisms Oct 2022is a ubiquitous Gram-negative opportunistic pathogen in the freshwater environment and the most common cause of bacterial septicemia in aquaculture. In this study, we...
is a ubiquitous Gram-negative opportunistic pathogen in the freshwater environment and the most common cause of bacterial septicemia in aquaculture. In this study, we investigated the impact of carvacrol, a natural monoterpenoid found in herbs, on the virulence of in vitro and the antibacterial effect in combination with antibiotics. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of carvacrol against NJ-35 were 125 µg/mL and 250 µg/mL, respectively. Carvacrol could inhibit the virulence factors (biofilm, protease, exopolysaccharide, and hemolysin) of , and the antibiofilm potential of carvacrol was further verified by microscopic detection. Transcriptional analyses showed that the gene expression of , , , , , , , , and were marked as downregulated. The checkerboard assay results showed that carvacrol did not have an antagonistic effect in combination with antibiotics (florfenicol, enrofloxacin, thiamphenicol, or doxycycline hydrochloride) commonly used in aquaculture but possessed an additive-synergistic effect with neomycin sulfate. In vivo studies demonstrated that carvacrol protected grass carp () from infection. Our results indicated that carvacrol possessed significant anti-bacterial and anti-virulence effects on .
PubMed: 36363761
DOI: 10.3390/microorganisms10112170 -
Journal of Infection in Developing... Jan 2023Aeromonas spp. are widely distributed in surface water, sewage, untreated and chlorinated, drinking water, as well as meats, fish, shellfish, poultry, and their... (Review)
Review
Aeromonas spp. are widely distributed in surface water, sewage, untreated and chlorinated, drinking water, as well as meats, fish, shellfish, poultry, and their products. A disease caused by Aeromonas spp. is designated as aeromoniasis. It can affect different aquatic animals, mammals, and birds in different geographic regions. Moreover, gastrointestinal and extra-intestinal disease conditions may be provoked in humans as a result of food poising with Aeromonas spp. Some Aeromonas spp. have been identified, however, Aeromonas hydrophila (A. hydrophila), A. caviae, and A. veronii bv sobria may be of public health significance. Aeromonas spp. are members of family Aeromonadaceae and genus Aeromonas. They are Gram-negative rod-shaped, facultative anaerobic, and oxidase and catalase-positive bacteria. The pathogenicity of Aeromonas in different hosts is mediated by several virulence factors such as endotoxins, cytotoxic enterotoxin, cytotoxins, hemolysins, adhesins, and extracellular enzymes such as proteases, amylases, lipases, ADP-ribosyltransferases, and DNases. Most avian species are susceptible to either natural or experimental infections with Aeromonas spp. Infection usually arises through feacal-oral route. Traveler's diarrhea as well as other systemic and local infections are the clinical picture of food poisoning associated with aeromoniasis in humans. Despite Aeromonas spp. being sensitive to various antimicrobials, multiple drug resistance has been commonly reported worldwide. Accordingly, this review highlights aeromoniasis in poultry regarding Aeromonas virulence factors epidemiology, pathogenicity, zoonosis, and antimicrobial resistance.
Topics: Animals; Humans; Diarrhea; Poultry; Drug Resistance, Bacterial; Travel; Bacterial Infections; Aeromonas; Virulence Factors; Gram-Negative Bacterial Infections; Mammals
PubMed: 36795920
DOI: 10.3855/jidc.17186 -
Frontiers in Veterinary Science 2023
PubMed: 37065242
DOI: 10.3389/fvets.2023.1174494 -
Heliyon Mar 2023is a freshwater, facultatively anaerobic, chemo-organoheterotrophic bacterium that distressed fishes with gastroenteritis, septicemia and causes a disease known as... (Review)
Review
is a freshwater, facultatively anaerobic, chemo-organoheterotrophic bacterium that distressed fishes with gastroenteritis, septicemia and causes a disease known as Motile Aeromonas Septicemia (MAS), which affects the aquatic environment. Haemolysin, aerolysin, cytosine, gelatinase, enterotoxin and antimicrobial peptides have been identified as virulence factors in . Medicinal herbs/plants and their uses are the instant, easily available, cost-effective, efficient and eco-friendly approach for socio-economic, sustainable development of modern aquaculture practice. Phytotherapy either through a dip or by incorporation into the diets is an alternative approach to synthetic pharmaceuticals to diminish the pathogenicity of aquatic environmental pathogens. Due to the presence of remarkable phytoconstituents like flavonoids, alkaloids, pigments, terpenoids, steroids and essential oils, the medicinal plant exhibits anti-microbial, appetite-stimulating, anti-stress, growth-promoting and immunostimulatory activities. Aqua-industry preferred phytotherapy-based techniques/compounds to develop resistance against a variety of aquatic pathogens in culturable fishes because they are inexpensive and environment-friendly. As a result, this review elaborates on the diverse applications of phytotherapy as a promising tool for disease management in aquaculture and a major step toward organic aquaculture.
PubMed: 36938468
DOI: 10.1016/j.heliyon.2023.e14088 -
Frontiers in Immunology 2023is a kind of zoonotic pathogen, which can cause bacterial septicemia in fish and bring huge economic losses to global aquaculture. Outer membrane proteins (Omps) are...
is a kind of zoonotic pathogen, which can cause bacterial septicemia in fish and bring huge economic losses to global aquaculture. Outer membrane proteins (Omps) are conserved antigens of , which can be developed as subunit vaccines. To evaluate the protective efficacy of inactivated vaccine and recombinant outer membrane protein A (OmpA) subunit vaccine against in juvenile , the present study investigated the immunogenicity and protective effects of both vaccines, as well as the non-specific and specific immune response of . Compared with the non-vaccinated group, both inactivated and OmpA subunit vaccines improved the survival rate of upon infection. The protective effects of OmpA vaccine groups were better than that of the inactivated vaccine groups, which should be attributed to the reduced bacterial load and enhanced host immunity in the vaccinated fish. ELISA assay showed that the titer of serum immunoglobulin M (IgM) specific to up-regulated significantly in the OmpA subunit vaccine groups at 14 d post infection (dpi), which should contribute to better immune protective effects. In addition, vaccination enhanced host bactericidal abilities might also attribute to the regulation of the activities of hepatic and serum antimicrobial enzymes. Moreover, the expression of immune-related genes ( and ) increased in all groups post infection, which was more significant in the vaccinated groups. Furthermore, the number of immunopositive cells exhibiting different epitopes (CD8, IgM, IgD and IgZ) that were detected by immunohistochemical assay had increased in the vaccinated groups post infection. These results show that vaccination effectively stimulated host immune response (especially OmpA vaccine groups). In conclusion, these results indicated that both the inactivated vaccine and OmpA subunit vaccine could protect juvenile against infection, of which OmpA subunit vaccine provided more effective immune protection and can be used as an ideal candidate for the vaccine.
Topics: Animals; Aeromonas hydrophila; Vaccines, Inactivated; Bacterial Vaccines; Cypriniformes; Immunoglobulin M; Vaccines, Synthetic; Vaccines, Subunit
PubMed: 36969197
DOI: 10.3389/fimmu.2023.1133742 -
Frontiers in Microbiology 2016The ubiquitous "jack-of-all-trades," Aeromonas hydrophila, is a freshwater, Gram-negative bacterial pathogen under revision in regard to its phylogenetic and functional... (Review)
Review
The ubiquitous "jack-of-all-trades," Aeromonas hydrophila, is a freshwater, Gram-negative bacterial pathogen under revision in regard to its phylogenetic and functional affiliation with other aeromonads. While virulence factors are expectedly diverse across A. hydrophila strains and closely related species, our mechanistic knowledge of the vast majority of these factors is based on the molecular characterization of the strains A. hydrophila AH-3 and SSU, which were reclassified as A. piscicola AH-3 in 2009 and A. dhakensis SSU in 2013. Individually, these reclassifications raise important questions involving the applicability of previous research on A. hydrophila virulence mechanisms; however, this issue is exacerbated by a lack of genomic data on other research strains. Collectively, these changes represent a fundamental gap in the literature on A. hydrophila and confirm the necessity of biochemical, molecular, and morphological techniques in the classification of research strains that are used as a foundation for future research. This review revisits what is known about virulence in A. hydrophila and the feasibility of using comparative genomics in light of this phylogenetic revision. Conflicting data between virulence factors, secretion systems, quorum sensing, and their effect on A. hydrophila pathogenicity appears to be an artifact of inappropriate taxonomic comparisons and/or be due to the fact that these properties are strain-specific. This review audits emerging data on dominant virulence factors that are present in both A. dhakensis and A. hydrophila in order to synthesize existing data with the aim of locating where future research is needed.
PubMed: 27610107
DOI: 10.3389/fmicb.2016.01337 -
BMC Microbiology Jun 2020Aeromonas hydrophila is an important water-borne pathogen that leads to a great economic loss in aquaculture. Along with the abuse of antibiotics, drug-resistant strains...
BACKGROUND
Aeromonas hydrophila is an important water-borne pathogen that leads to a great economic loss in aquaculture. Along with the abuse of antibiotics, drug-resistant strains rise rapidly. In addition, the biofilms formed by this bacterium limited the antibacterial effect of antibiotics. Bacteriophages have been attracting increasing attention as a potential alternative to antibiotics against bacterial infections.
RESULTS
Five phages against pathogenic A. hydrophila, named N21, W3, G65, Y71 and Y81, were isolated. Morphological analysis by transmission electron microscopy revealed that phages N21, W3 and G65 belong to the family Myoviridae, while Y71 and Y81 belong to the Podoviridae. These phages were found to have broad host spectra, short latent periods and normal burst sizes. They were sensitive to high temperature but had a wide adaptability to the pH. In addition, the phages G65 and Y81 showed considerable bacterial killing effect and potential in preventing formation of A. hydrophila biofilm; and the phages G65, W3 and N21 were able to scavenge mature biofilm effectively. Phage treatments applied to the pathogenic A. hydrophila in mice model resulted in a significantly decreased bacterial loads in tissues.
CONCLUSIONS
Five A. hydrophila phages were isolated with broad host ranges, low latent periods, and wide pH and thermal tolerance. And the phages exhibited varying abilities in controlling A. hydrophila infection. This work presents promising data supporting the future use of phage therapy.
Topics: Aeromonas hydrophila; Animals; Bacterial Load; Bacteriophages; Biofilms; Disease Models, Animal; Gram-Negative Bacterial Infections; Hot Temperature; Hydrogen-Ion Concentration; Mice; Microscopy, Electron, Transmission; Myoviridae; Phage Therapy; Podoviridae
PubMed: 32487015
DOI: 10.1186/s12866-020-01811-w -
Frontiers in Microbiology 2022Aeromonads are ubiquitous in aquatic environments and several species are opportunistic pathogens of fish. Disease losses caused by motile species, particularly , can...
INTRODUCTION
Aeromonads are ubiquitous in aquatic environments and several species are opportunistic pathogens of fish. Disease losses caused by motile species, particularly , can be challenging in intensive aquaculture, such as at striped catfish () farms in Vietnam. Outbreaks require antibiotic treatments, but their application is undesirable due to risks posed by resistance. Vaccines are an attractive prophylactic and they must protect against the prevalent strains responsible for ongoing outbreaks.
METHODS
This present study aimed to characterize strains associated with mortalities in striped catfish culture in the Mekong Delta by a polyphasic genotyping approach, with a view to developing more effective vaccines.
RESULTS
During 2013-2019, 345 presumptive spp. isolates were collected at farms in eight provinces. Repetitive element sequence-based PCR, multi-locus sequence typing and whole-genome sequencing revealed most of the suspected 202 isolates to belong to ST656 ( = 151), which corresponds to the closely-related species , with a lesser proportion belonging to ST251 ( = 51), a hypervirulent lineage (vAh) of already causing concern in global aquaculture. The ST656 and vAh ST251 isolates from outbreaks possessed unique gene sets compared to published and vAh ST251 genomes, including antibiotic-resistance genes. The sharing of resistance determinants to sulphonamides () and trimethoprim () suggests similar selection pressures acting on ST656 and vAh ST251 lineages. The earliest isolate (a vAh ST251 from 2013) lacked most resistance genes, suggesting relatively recent acquisition and selection, and this underscores the need to reduce antibiotics use where possible to prolong their effectiveness. A novel PCR assay was designed and validated to distinguish and vAh ST251 strains.
DISCUSSION
This present study highlights for the first time , a zoonotic species that can cause fatal human infection, to be an emerging pathogen in aquaculture in Vietnam, with widespread distribution in recent outbreaks of motile septicaemia in striped catfish. It also confirms vAh ST251 to have been present in the Mekong Delta since at least 2013. Appropriate isolates of and vAh should be included in vaccines to prevent outbreaks and reduce the threat posed by antibiotic resistance.
PubMed: 36794008
DOI: 10.3389/fmicb.2022.1067235