ABSTRACT
Several farmed fish species, including carps, tilapia, salmon, and catfish, have experienced significant economic losses in aquaculture due to motile Aeromonas septicemia caused by Aeromonas hydrophila. In the present study, a novel lytic bacteriophage infecting hypervirulent Aeromonas hydrophila (vAh) was isolated and characterized. This is the first report of a phage against vAh. Phage AhFM11 demonstrated lytic activity against both vAh strains and the A. hydrophila reference strain ATCC 35654. The AhFM11 genome was sequenced and assembled, comprising 168,243 bp with an average G + C content of 41.5%. The genome did not harbor any antibiotic resistance genes. Genomic information along with transmission electron microscopy revealed that phage AhFM11 belongs to the Straboviridae family. Therapeutic application of monophage AhFM11 in fish showed 100% survival in injection, 95% in immersion and 93% in oral feeding of phage top-coated feed. Fish and chicken meat spiked with A. hydrophila and phage showed significant reduction of A. hydrophila. These findings support that phage AhFM11 can be used as a biocontrol agent against vAh as an alternative to antibiotics.
Subject(s)
Aeromonas hydrophila , Bacteriophages , Gram-Negative Bacterial Infections , Aeromonas hydrophila/virology , Aeromonas hydrophila/pathogenicity , Bacteriophages/genetics , Bacteriophages/physiology , Bacteriophages/pathogenicity , Bacteriophages/isolation & purification , Animals , Gram-Negative Bacterial Infections/therapy , Gram-Negative Bacterial Infections/microbiology , Gram-Negative Bacterial Infections/veterinary , Phage Therapy/methods , Fish Diseases/microbiology , Fish Diseases/therapy , Genome, Viral , Fishes/microbiology , VirulenceABSTRACT
Edwardsiella piscicida causes significant economic losses to the aquaculture industry worldwide. Phage-based biocontrol methods are experiencing a renaissance because of the spread of drug-resistant genes and bacteria resulting from the heavy use of antibiotics. Here, we showed that the novel Edwardsiella phage EPP-1 could achieve comparable efficacy to florfenicol using a zebrafish model of Edwardsiella piscicida infection and could reduce the content of the floR resistance gene in zebrafish excreta. Specifically, phage EPP-1 inhibited bacterial growth in vitro and significantly improved the zebrafish survival rate in vivo (P = 0.0035), achieving an efficacy comparable to that of florfenicol (P = 0.2304). Notably, integrating the results of 16S rRNA sequencing, metagenomic sequencing, and qPCR, although the effects of phage EPP-1 converged with those of florfenicol in terms of the community composition and potential function of the zebrafish gut microbiota, it reduced the floR gene content in zebrafish excreta and aquaculture water. Overall, our study highlights the feasibility and safety of phage therapy for edwardsiellosis control, which has profound implications for the development of antibiotic alternatives to address the antibiotic crisis.
Subject(s)
Anti-Bacterial Agents , Bacteriophages , Edwardsiella , Enterobacteriaceae Infections , Thiamphenicol/analogs & derivatives , Zebrafish , Animals , Zebrafish/microbiology , Edwardsiella/genetics , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae Infections/veterinary , Enterobacteriaceae Infections/therapy , Bacteriophages/genetics , Bacteriophages/physiology , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial/genetics , Gastrointestinal Microbiome , Phage Therapy/methods , RNA, Ribosomal, 16S/genetics , Fish Diseases/microbiology , Fish Diseases/therapy , Fish Diseases/prevention & control , Thiamphenicol/pharmacology , Aquaculture/methodsABSTRACT
Photobiomodulation therapy (PBMT) has become increasingly utilized in the zoo and aquarium fields to treat ailments in various species; however, its use in teleosts and elasmobranchs is relatively underrepresented in the literature. This study examined the efficacy of PBMT as an adjunct treatment to reduce the healing time of dermal abrasions in cownose rays (Rhinoptera bonasus). Ten cownose rays were included in this study and separated into control (n = 5) and treatment groups (n = 5). Animals in both treatment and control groups received intramuscular injections of enrofloxacin every 72 h to provide broad-spectrum antibiotic coverage. Cownose rays in the treatment group additionally received PBMT using the Companion® CTC-12 unit using the large, noncontact head. Control group rays were subjected to identical handling without the use of PBMT. A total of 196 Joules were delivered at a power of 2 W based on a dose of 5 J/cm2 at each session. Observational analysis revealed a lack of appreciable difference in healing time between the treatment and control groups in the aforementioned settings; however, it is recommended that PBMT protocols should be re-evaluated if there is little to no response in healing after three to four sessions. PBMT use on acute superficial dermal abrasions in cownose rays was well-tolerated in this study and may have utility in a multimodal treatment approach to wound healing. This study also produced a wound scoring metric based on photographs captured at each treatment. Future studies should utilize increased fluence (J/cm2) and irradiance (W/cm2) and incorporate synchronous histological analysis and increased sample size.
Subject(s)
Low-Level Light Therapy , Skates, Fish , Animals , Low-Level Light Therapy/veterinary , Low-Level Light Therapy/methods , Fish Diseases/therapy , Wound Healing/radiation effectsABSTRACT
The spread of multi-drug resistant (MDR) bacteria has posed a threat to the development of aquaculture. Due to its effective bactericidal ability, phage therapy has been considered as an alternative to antibiotics to reduce infection caused by MDR bacteria. In this study, two Edwardsiella piscicida phages were newly-isolated and characterized to prevent or treat infection in aquaculture. The phages were designated as vB_EpM_ZHS and vB_EpP_ZHX belonging to Myoviridae and Podoviridae families, respectively, in terms of genome sequence and morphology analyses. The combination of vB_EpM_ZHS and vB_EpP_ZHX improved the therapeutic efficacy both in vitro and in vivo. The phage cocktail significantly inhibited bacterial growth in vitro and decreased approximately 40% of mortality rate and an order of magnitude of bacterial burden in zebrafish and turbot infected by E. piscicida. Moreover, the phage cocktail increased transcription levels of tumor necrosis factor-alpha (TNF-α), interleukin-12 (IL-12), interleukin-6 (IL-6), and interleukin-1ß (IL-1ß) and alleviated inflammatory levels in the hindgut and spleen of turbots. The results indicate that the phage has a promising potential for therapeutic use against E. piscicida as the antimicrobial alternative to antibiotics in aquaculture.
Subject(s)
Bacteriophages , Edwardsiella , Enterobacteriaceae Infections , Fish Diseases , Flatfishes , Animals , Anti-Bacterial Agents/pharmacology , Edwardsiella/genetics , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae Infections/therapy , Enterobacteriaceae Infections/veterinary , Fish Diseases/microbiology , Fish Diseases/therapy , ZebrafishABSTRACT
Phage therapy can be an effective alternative to standard antimicrobial chemotherapy for control of Aeromonas hydrophila infections in aquaculture. Aeromonas hydrophila-specific phages AhMtk13a and AhMtk13b were studied for basic biological properties and genome characteristics. Phage AhMtk13a (Myovirus, 163,879 bp genome, 41.21% CG content) was selected based on broad lytic spectrum and physiologic parameters indicating its lytic nature. The therapeutic potential of phage AhMtk13a was evaluated in experimental studies in zebrafish challenged with A. hydrophila GW3-10 via intraperitoneal injection and passive immersion in aquaria water. In experimental series 1 with single introduction of AhMtk13a phage to aquaria water at phage-bacteria ratio 10:1, cumulative mortality 44% and 62% was registered in fish exposed to phage immediately and in 4 h after bacterial challenge, correspondingly, compared to 78% mortality in the group with no added phage. In experimental series 2 with triple application of AhMtk13a phage at ratio 100:1, the mortality comprised 15% in phage-treated group compared to the 55% in the control group. Aeromonas hydrophila GW3-10 was not detectable in aquaria water from day 9 but still present in fish at low concentration. AhMtk13a phage was maintained in fish and water throughout the experiment at the higher concentration in infected fish.
Subject(s)
Bacteriophages/genetics , Fish Diseases/therapy , Gram-Negative Bacterial Infections/therapy , Phage Therapy/methods , Zebrafish/microbiology , Aeromonas hydrophila/virology , Animals , Aquaculture , Fish Diseases/microbiology , Genome, Viral , Gram-Negative Bacterial Infections/virologyABSTRACT
Rainbow trout fry syndrome (RTFS) and bacterial coldwater disease (BCWD) is a globally distributed freshwater fish disease caused by Flavobacterium psychrophilum. In spite of its importance, an effective vaccine is not still available. Manipulation of the microbiome of skin, which is a primary infection gate for pathogens, could be a novel countermeasure. For example, increasing the abundance of specific antagonistic bacteria against pathogens in fish skin might be effective to prevent fish disease. Here, we combined cultivation with 16S rRNA gene amplicon sequencing to obtain insight into the skin microbiome of the rainbow trout (Oncorhynchus mykiss) and searched for skin bacteria antagonistic to F. psychrophilum. By using multiple culture media, we obtained 174 isolates spanning 18 genera. Among them, Bosea sp. OX14 and Flavobacterium sp. GL7 respectively inhibited the growth of F. psychrophilum KU190628-78 and NCIMB 1947T, and produced antagonistic compounds of < 3 kDa in size. Sequences related to our isolates comprised 4.95% of skin microbial communities, and those related to strains OX14 and GL7 respectively comprised 1.60% and 0.17% of the skin microbiome. Comparisons with previously published microbiome data detected sequences related to strains OX14 and GL7 in skin of other rainbow trout and Atlantic salmon.
Subject(s)
Fish Diseases/therapy , Flavobacterium/drug effects , Oncorhynchus mykiss/microbiology , Animals , Aquaculture/methods , Fish Diseases/microbiology , Flavobacteriaceae Infections/microbiology , Flavobacteriaceae Infections/therapy , Flavobacterium/genetics , Flavobacterium/pathogenicity , Oncorhynchus mykiss/genetics , Skin/microbiologyABSTRACT
Skin lesions are frequently diagnosed in fish medicine. Although systemic fish treatments exist, little is known about the efficacy of topical drugs on fish skin lesions. This study aimed to investigate the efficacy of medical-grade honey and silver sulfadiazine on skin lesions using common carp (Cyprinus carpio) as a model. Additionally, the effect of temperature on the wound healing process was evaluated. Punch biopsies were generated on six fish per treatment group under anesthesia. Treatment groups received one of the following topical medications after wounding: Dr. Nordyke's Wound Honey, MicroLyte Ag Vet, or SilvaSorb Gel. Nontreated positive control groups were similarly wounded but did not receive topical treatment. Fish were housed at 10°C to 13°C or 18°C to 21°C for 29 days. Macroscopic evaluation and image collection of wounds were performed on days 0, 4, 8, 12, 21, and 29 after wounding to compare changes in wound areas and inflammation over time. On day 29, tissue samples were collected for histologic analysis. From day 12 after wounding onward, wounds in positive controls maintained at 18°C to 21°C were significantly smaller (days 12, 21, and 29: P < 0.0001) compared with positive controls kept at 10°C to 13°C. There was an overall improvement in macroscopic appearance in honey-treated groups compared with positive controls on day 12 after wounding at 18°C to 21°C (P = 0.001), whereas with the use of Microlyte and Silvasorb, wounds had increased inflammation grades (P < 0.0001 and P < 0.0001, respectively) with enlarged wound areas (P < 0.0001 and P < 0.001, respectively) in comparison with positive controls on day 12 after wounding at 18°C to 21°C. This study suggests that topical use of medical-grade honey produces positive effects on wound healing in the carp model and higher water temperatures enhance the effects, whereas the use of silver sulfadiazine and lower water temperatures delays or worsens the wound healing process.
Subject(s)
Anti-Infective Agents, Local/therapeutic use , Carps/injuries , Honey , Silver Sulfadiazine/therapeutic use , Temperature , Wound Healing/drug effects , Administration, Topical , Animals , Anti-Infective Agents, Local/administration & dosage , Fish Diseases/therapy , Silver Sulfadiazine/administration & dosage , Skin/pathology , WaterABSTRACT
Artificial breeding of small yellow croaker (Larimichthys polyactis) was recently achieved, providing a bright future for its commercial farming. In May 2019, a disease outbreak occurred among small yellow croakers in an aquaculture farm near Xiangshan Bay, charactering by white spots spotted on the surface of fish skin, gills and fins. The parasite was preliminarily identified as Cryptocaryon irritans based on morphological feature of the parasite and the symptoms on fish. However, the previously published specific primer pairs failed to confirm the existence of C. iriitans. Six nucleotides mismatches were discovered after mapping specific forward primer back to targeted gene. Therefore, an updated PCR specific primer was developed within the 9th highly variable region of 18S rRNA gene and conserved in all C. irritans sequences available in GenBank database. The specificity was verified in silico by Primer-BLAST against GenBank nucleotide. Laboratory cultured ciliates (Mesanophrys, Pseudokeronopsis and Uronema) as well as natural microbial community samples collected from sea water and river water was used as negative control to verify the specificity of the primer in situ. Besides, tank transfer method was used to evaluate the treatment of the parasite infection. By tank transfer method, 2.00 ± 0.61 out of 10 fish that already sever infected were successfully survived after 8 days treatment, meanwhile the control group died out at d 6. More loss to the treatment group during first five days was observed and may attribute to the combined effect from infection and stress the recent domesticated fish suffered during rotation. Therefore, tank transfer method was also effective to prevent small yellow croaker from further infection, however the loss of the small yellow croaker suffered from stress during rotation also needs to be carefully concerned. In conclusion, this study reported the first diagnose of C. irritans infection on small yellow croaker, provided updated specific primer to detect C. irritans infection on fish body and reported the effect of tank transfer on small yellow croaker treatment.
Subject(s)
Ciliophora Infections/veterinary , Ciliophora/isolation & purification , Fish Diseases/parasitology , Perciformes/parasitology , Animal Fins/parasitology , Animal Fins/pathology , Animals , China/epidemiology , Ciliophora/classification , Ciliophora/genetics , Ciliophora Infections/diagnosis , Ciliophora Infections/epidemiology , Ciliophora Infections/parasitology , Disease Outbreaks/veterinary , Fish Diseases/diagnosis , Fish Diseases/epidemiology , Fish Diseases/therapy , Fisheries , Gills/parasitology , Gills/pathology , Muscle, Skeletal/parasitology , Muscle, Skeletal/pathology , Phylogeny , RNA, Ribosomal, 18S/genetics , Skin/parasitology , Skin/pathology , Species SpecificityABSTRACT
As pain management finally becomes accepted for this last of the vertebrate taxa, fish medicine is finally reaching the sophistication of other vertebrates. The diseases of aging fish in captivity therefore need to be addressed. The degenerative organ/tissue changes and neoplasias of fish deserve the same diagnosis and treatments of their terrestrial counterparts including pain relief, anti-inflammatory medications, chemotherapy, surgery, joint supplements, regenerative cell therapy, and photobiomodulation. Besides the challenges of an aquatic environment, recognizing normal changes in older fish will be addressed in this article. Clinicians can appreciate the diversity of fishes and their unique anatomies, physiologies, and behaviors which translate to creative medicine.
Subject(s)
Aging , Biodiversity , Fish Diseases/diagnosis , Fishes/physiology , Pain Management/veterinary , Veterinary Medicine , Animals , Fish Diseases/therapy , Fishes/anatomy & histology , Fresh Water , SeawaterABSTRACT
This study proposed that phage-enriched artemia could be a useful tool for transferring phage into the cultured fish (larvae or adult) as a feed, and introduce mode of phage administration and its safety in concern of tissue adaptation for efficient phage therapy in aquatic animals. First, whether Edwardsiella tarda phage (ETP-1) could attach or ingest by the artemia and optimum time period for the ETP-1 enrichment with artemia were investigated. ETP-1 dispersion, abundance and persistency, and zebrafish immune transcriptional responses and histopathology were evaluated after feeding the fish with ETP-1-enriched artemia. Hatched artemia nauplii (36 h) were enriched with 1.90 × 1011 PFUmL-1 of ETP-1, and maintained at 25 °C. The highest enrichment level was obtained after 4 h (3.00 × 109 PFUmL-1), and artemia were alive and active similar to control for 8 h. ETP-1 disseminated dose dependently to all the tissues rapidly (12 h). However, when feeding discontinued, it drastically decreased at day 3 with high abundance and persistency in the spleen (1.02 × 103) followed by the kidney (4.00 × 101) and the gut (1 × 101 PFUmL-1) for highest ETP-1-enriched artemia dose. In contrast, during continuous delivery of ETP-1-enriched artemia, ETP-1 detected in all the tissues (at day 10: gut; 1.90 × 107, kidney; 3.33 × 106, spleen; 5.52 × 105, liver; 6.20 × 104 PFUmL-1mg-1 tissues). Though the phage abundance varied, results indicated that oral fed ETP-1-enriched artemia disperse to the neighboring organs, even the absence of host as phage carrier. Non-significant differences of immune transcriptional and histopathology analysis between ETP-1-enriched artemia fed and controls suggest that no adverse apparent immune stimulation in host occurred, and use of ETP-1 at 1011 PFUmL-1 was safe. With further supportive studies, live artemia-mediated phage delivery method could be used as a promising tool during phage therapy against pathogenic bacteria to control aquatic diseases.
Subject(s)
Animal Feed/virology , Artemia/virology , Edwardsiella tarda/virology , Phage Therapy/methods , Animal Feed/analysis , Animals , Aquaculture/methods , Fish Diseases/therapy , Microspheres , Transcriptome , Zebrafish/immunology , Zebrafish/virologyABSTRACT
BACKGROUND: Parasites employ proteases to evade host immune systems, feed and replicate and are often the target of anti-parasite strategies to disrupt these interactions. Myxozoans are obligate cnidarian parasites, alternating between invertebrate and fish hosts. Their genes are highly divergent from other metazoans, and available genomic and transcriptomic datasets are limited. Some myxozoans are important aquaculture pathogens such as Sphaerospora molnari replicating in the blood of farmed carp before reaching the gills for sporogenesis and transmission. Proliferative stages cause a massive systemic lymphocyte response and the disruption of the gill epithelia by spore-forming stages leads to respiratory problems and mortalities. In the absence of a S. molnari genome, we utilized a de novo approach to assemble the first transcriptome of proliferative myxozoan stages to identify S. molnari proteases that are upregulated during the first stages of infection when the parasite multiplies massively, rather than in late spore-forming plasmodia. Furthermore, a subset of orthologs was used to characterize 3D structures and putative druggable targets. RESULTS: An assembled and host filtered transcriptome containing 9436 proteins, mapping to 29,560 contigs was mined for protease virulence factors and revealed that cysteine proteases were most common (38%), at a higher percentage than other myxozoans or cnidarians (25-30%). Two cathepsin Ls that were found upregulated in spore-forming stages with a presenilin like aspartic protease and a dipeptidyl peptidase. We also identified downregulated proteases in the spore-forming development when compared with proliferative stages including an astacin metallopeptidase and lipases (qPCR). In total, 235 transcripts were identified as putative proteases using a MEROPS database. In silico analysis of highly transcribed cathepsins revealed potential drug targets within this data set that should be prioritised for development. CONCLUSIONS: In silico surveys for proteins are essential in drug discovery and understanding host-parasite interactions in non-model systems. The present study of S. molnari's protease arsenal reveals previously unknown proteases potentially used for host exploitation and immune evasion. The pioneering dataset serves as a model for myxozoan virulence research, which is of particular importance as myxozoan diseases have recently been shown to emerge and expand geographically, due to climate change.
Subject(s)
Carps/microbiology , Fish Diseases/parasitology , Myxozoa/genetics , Parasitic Diseases, Animal/parasitology , Peptide Hydrolases/genetics , Animals , Antiparasitic Agents/pharmacology , Antiparasitic Agents/therapeutic use , Drug Discovery , Fish Diseases/therapy , Myxozoa/growth & development , Parasitic Diseases, Animal/therapy , Phylogeny , Transcriptome , Virulence FactorsABSTRACT
AIMS: This study describes the effect of phage therapy on hatching of longfin yellowtail (Seriola rivoliana) eggs challenged with Photobacterium damselae subsp. damselae. METHODS AND RESULTS: A lytic phage (vB_Pd_PDCC-1) against P. damselae subsp. damselae was isolated and characterized. The use of phage vB_Pd_PDCC-1 increased the hatching rate of eggs, and reduced presumptive Vibrio species to non-detectable numbers, even in non-disinfected eggs. High-throughput 16S rRNA gene sequencing analysis revealed that phage vB_Pd_PDCC-1 caused significant changes in the composition and structure of the associated microbiota, allowing that members (e.g. those belonging to the family Vibrionaceae) of the class Gammaproteobacteria to be displaced by members of the class Alphaproteobacteria. CONCLUSIONS: To the best of our knowledge, this represents the first study evaluating phage therapy to control potential negative effects of P. damselae subsp. damselae during hatching of longfin yellowtail eggs. SIGNIFICANCE AND IMPACT OF THE STUDY: The Seriola genus includes several important commercial fish species due to its rapid growth and easy adaptability to confinement conditions. However, bacterial infections (especially those caused by Vibrio and Photobacterium species) are among the main limiting factors for the intensification of marine fish aquaculture, particularly during early development stages. Therefore, the use of phages, which are natural killers of bacteria, represents a promising strategy to reduce the mortality of farmed organisms caused by pathogenic bacteria.
Subject(s)
Bacteriophages/physiology , Biological Control Agents/pharmacology , Fish Diseases/therapy , Fishes/microbiology , Gram-Negative Bacterial Infections/veterinary , Photobacterium/drug effects , Animals , Aquaculture , Fish Diseases/microbiology , Fishes/physiology , Gram-Negative Bacterial Infections/microbiology , Gram-Negative Bacterial Infections/therapy , Microbiota/drug effects , Ovum/microbiology , Ovum/physiology , Phage Therapy , Photobacterium/growth & developmentABSTRACT
In the current study, we investigated the effect of a probiotic bacterium (Lactobacillus rhamnosus ATCC 7469) microencapsulated with alginate and hi-maize starch and coated with chitosan on improving growth factors, body composition, blood chemistry, and the immune response of rainbow trout (initial weight: 18.41 ± 0.32 g). Four experimental diets were formulated to feed fish for 60 days. They were control diet without any additive (C), diet added with beads without probiotic (E), a probiotic sprayed to the diet (L.r), and encapsulated probiotic supplemented diet (E-L.r). The results indicated that feeding with E-Lr significantly improved weight gain (84.98 g) and feed conversion ratio (0.95) compared to the other groups (P < 0.05). Also, fish fed E-Lr diet had a significantly higher value of whole-body protein (17.51%), total protein in the blood (4.98 g/dL), lysozyme (30.66 U/mL), alternative complement pathway hemolytic activity (134 U/mL), superoxide dismutase (203 U/mg protein), and catalase (528.33 U/mg protein) (P < 0.05) as compared to those fed the control diet. Similarly, a higher relative expression of immune-related genes such as interleukin-1 (Il-1) and tumor necrosis factor-alpha (TNF-1α) were reported in those fed E-L.r and L.r diets respectively. Interestingly, the fish fed dietary E-L.r had a significantly lower value of lipid in the whole body (4.82%) and cholesterol in the blood (160.67%) in comparison with those fed the control diet (P < 0.05). At the end of the experiment, all groups were challenged by Yersinia ruckeri where the survival rate of rainbow trout fed dietary E-L.r (70.36%) was statistically higher than that of the others (P < 0.05). Overall, the results suggested that encapsulated probiotic Lact. rhamnosus ATCC 7469 acted better than unencapsulated probiotic and has a potential to improve growth performance, flesh quality, and the immune response of rainbow trout.
Subject(s)
Fish Diseases/therapy , Fish Proteins/genetics , Gene Expression Regulation/drug effects , Lacticaseibacillus rhamnosus/physiology , Oncorhynchus mykiss/immunology , Probiotics/pharmacology , Yersinia Infections/therapy , Alginates/chemistry , Animal Feed/analysis , Animals , Body Composition/drug effects , Catalase/genetics , Catalase/immunology , Cell Encapsulation/methods , Cells, Immobilized , Chitosan/chemistry , Cholesterol/blood , Complement Pathway, Alternative/drug effects , Diet , Disease Resistance/drug effects , Disease Resistance/genetics , Disease Resistance/immunology , Fish Diseases/immunology , Fish Diseases/microbiology , Fish Proteins/immunology , Gene Expression Regulation/immunology , Interleukin-1/genetics , Interleukin-1/immunology , Muramidase/genetics , Muramidase/immunology , Oncorhynchus mykiss/growth & development , Oncorhynchus mykiss/microbiology , Superoxide Dismutase/genetics , Superoxide Dismutase/immunology , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/immunology , Weight Gain/drug effects , Yersinia Infections/immunology , Yersinia Infections/microbiology , Yersinia ruckeri/drug effects , Yersinia ruckeri/growth & development , Yersinia ruckeri/pathogenicityABSTRACT
Edwardsiella tarda phage (ETP-1) was isolated from marine fish farm water to characterize its effect against pathogenic multidrug-resistant E. tarda. According to transmission electron microscopy results, ETP-1 is classified as a member of the family Podoviridae. ETP-1 showed MOI dependent E. tarda growth inhibition, a latent period of 60 min, and burst size of 100 PFU per infected cells. In host range tests, five out of eight E. tarda strains were sensitive to ETP-1 which had efficiency of plating index in the range 1-1.28. ETP-1 was stable over a broad range of pH and temperature. The size of the ETP-1 genome was predicted to be approximately 40 kb. Zebrafish exposed to ETP-1 showed no adverse gene responses to the inflammatory mediator cytokines, il1-ß, tnf-α, il-6, and il-10, the chemokine, cxcl-8a, and reactive oxygen species, sod-1. When zebrafish were bath exposed to ETP-1 for 12 days and simultaneously challenged with E. tarda (1.08 × 105 CFU fish-1), the survival rate was higher in phage exposed fish (68%) compared to that of the control (18%) until 4 days post challenge. Our results suggest that ETP-1 can be used as a potential bio-therapeutic candidate to control multi-drug resistant E. tarda infection in aquaculture.
Subject(s)
Drug Resistance, Multiple, Bacterial , Edwardsiella tarda , Enterobacteriaceae Infections/therapy , Fish Diseases , Phage Therapy , Podoviridae , Animals , Edwardsiella tarda/pathogenicity , Edwardsiella tarda/virology , Fish Diseases/microbiology , Fish Diseases/therapy , ZebrafishABSTRACT
The ornamental fish industry is growing quickly globally. Asia represents 51% of the export market for this industry and in Singapore alone, it has an estimated market value of US$66 million. Despite the economic importance of this industry for Australasia, aquatic veterinary support for the ornamental fish sector is scarce. In many cases, ornamental fish owners do not seek advice from veterinarians. While the reasons behind this are difficult to elucidate, the low perceived value of fish compared to the cost of consulting a veterinarian, and limited knowledge about the availability of veterinary services for aquatic animals may contribute to the lack of interaction with veterinarians. Considering the growing importance of the ornamental fish industry, more education and data are needed about the services offered by veterinarians with aquatic animal health expertise. Knowledge on aquatic veterinary medicine is limited, reinforcing the need for more educational programmes and dissemination of aquatic veterinary services within the Australasian region.
Subject(s)
Animal Husbandry/methods , Fish Diseases/psychology , Fisheries , Health Knowledge, Attitudes, Practice , Veterinarians/psychology , Animals , Australasia , Fish Diseases/prevention & control , Fish Diseases/therapy , Fishes , Humans , Surveys and Questionnaires , Veterinary Medicine/methodsABSTRACT
To develop an alternative bio-control measure for multi-drug resistant pathogenic Aeromonas hydrophila, which causes motile Aeromonas septicemia in fish, novel virulent phage (AHP-1) was isolated from carp tissues. Morphological analysis by transmission electron microscopy revealed that AHP-1 belongs to Myoviridae family. AHP-1 displayed 81% of moderate adsorption by 25 min, and latent period of 40 min with burst size of 97 PFU mL-1 at an optimal multiplicity of infection (MOI) 0.1. AHP-1 was stable over a broad range of pH (4-11), temperature (4-50 °C), and salinity (0.1-3.5%). Both time and MOI dependent in vitro A. hydrophila growth inhibition was observed with AHP-1. AHP-1 (10 MOI) showed higher growth inhibition against A. hydrophila than chloramphenicol (5 µg mL-1), and combined treatment was more promising than individuals. Immune gene expression analysis of zebrafish upon continuous bath exposure to AHP-1 resulted significantly higher (il-6 and sod-1) or slight induction (tnf-α, il1-ß, il-10, and cxcl-8a) than controls at beginning of the phage exposure, but those lowered to basal level by day 12 post-phage exposure. It suggests no adverse immune responses have occurred for the AHP-1 dose that used, and have potential for the phage therapy. Further detailed in vivo studies are needed to confirm the protective efficacy of newly isolated AHP-1 against A. hydrophila infection.
Subject(s)
Aeromonas hydrophila , Fish Diseases/microbiology , Myoviridae/isolation & purification , Zebrafish/immunology , Aeromonas hydrophila/drug effects , Aeromonas hydrophila/virology , Animals , Bacteriophages/immunology , Bacteriophages/isolation & purification , Bacteriophages/ultrastructure , Biological Control Agents , Carps/virology , Chloramphenicol/pharmacology , Fish Diseases/therapy , Fishes , Immunity, Cellular , Myoviridae/immunology , Myoviridae/ultrastructure , Zebrafish/microbiology , Zebrafish/virologySubject(s)
Exophthalmos/veterinary , Fish Diseases , Perciformes , Wounds and Injuries/veterinary , Animals , Exophthalmos/etiology , Exophthalmos/prevention & control , Exophthalmos/therapy , Fish Diseases/etiology , Fish Diseases/prevention & control , Fish Diseases/therapy , Wounds and Injuries/etiology , Wounds and Injuries/prevention & control , Wounds and Injuries/therapyABSTRACT
The number of fish as pets far exceeds the populations of any other companion animal. As our knowledge of aquatic animal species and aquatic animal medicine continues to expand, veterinary expertise is becoming more critical to the client, researcher, fisheries biologist, aquarist, farmer, and fish hobbyist. Similar to other vertebrates, fish are susceptible to infectious and noninfectious renal disease. This article compares vertebrate renal anatomy and physiology and highlights some renal disease examples.
Subject(s)
Fish Diseases/diagnosis , Kidney Diseases/veterinary , Animals , Fish Diseases/physiopathology , Fish Diseases/therapy , Fishes , Kidney/anatomy & histology , Kidney/physiopathology , Kidney Diseases/diagnosis , Kidney Diseases/physiopathology , Kidney Diseases/therapy , VertebratesABSTRACT
Metazoans were proposed to host bacteriophages on their mucosal surfaces in a symbiotic relationship, where phages provide an external immunity against bacterial infections and the metazoans provide phages a medium for interacting with bacteria. However, scarce empirical evidence and model systems have left the phage-mucus interaction poorly understood. Here, we show that phages bind both to porcine mucus and to rainbow trout (Oncorhynchus mykiss) primary mucus, persist up to 7 days in the mucosa, and provide protection against Flavobacterium columnare Also, exposure to mucus changes the bacterial phenotype by increasing bacterial virulence and susceptibility to phage infections. This trade-off in bacterial virulence reveals ecological benefit of maintaining phages in the metazoan mucosal surfaces. Tests using other phage-bacterium pairs suggest that phage binding to mucus may be widespread in the biosphere, indicating its importance for disease, ecology, and evolution. This phenomenon may have significant potential to be exploited in preventive phage therapy.IMPORTANCE The mucosal surfaces of animals are habitat for microbes, including viruses. Bacteriophages-viruses that infect bacteria-were shown to be able to bind to mucus. This may result in a symbiotic relationship in which phages find bacterial hosts to infect, protecting the mucus-producing animal from bacterial infections in the process. Here, we studied phage binding on mucus and the effect of mucin on phage-bacterium interactions. The significance of our research is in showing that phage adhesion to mucus results in preventive protection against bacterial infections, which will serve as basis for the development of prophylactic phage therapy approaches. Besides, we also reveal that exposure to mucus upregulates bacterial virulence and that this is exploited by phages for infection, adding one additional layer to the metazoan-bacterium-phage biological interactions and ecology. This phenomenon might be widespread in the biosphere and thus crucial for understanding mucosal diseases, their outcome and treatment.
Subject(s)
Bacteria/pathogenicity , Bacteria/virology , Bacteriophages/physiology , Host-Pathogen Interactions , Mucous Membrane/microbiology , Mucous Membrane/virology , Mucus/virology , Animals , Antibiosis , Fish Diseases/microbiology , Fish Diseases/prevention & control , Fish Diseases/therapy , Flavobacterium/pathogenicity , Flavobacterium/virology , Mucus/metabolism , Phage Therapy , Protein Binding , Viral Proteins/metabolismABSTRACT
Pseudomonas aeruginosa is a Gram-negative opportunistic bacterial pathogen in aquaculture systems being associated to extensive liver damage caused by oxidative stress in both marine and freshwater fish. Dietary supplementation with natural antioxidants is considered a rational strategy to prevent hepatic diseases involved with oxidative stress. Bio-residues resulting from the wine industry, such as grape pomace, are potential sources of bioactive phenolic compounds that can be applied as supplement for animal production. Thus, the aim of this study was to evaluate whether dietary supplementation with grape pomace flour (GPF) was able to prevent or reduce the hepatic oxidative damage of grass carp, Ctenopharyngodon idella, experimentally infected by P. aeruginosa. Hepatic reactive oxygen species (ROS), metabolites of nitric oxide (NOx), thiobarbituric acid reactive substances, and protein carbonylation levels were higher in fish experimentally infected by P. aeruginosa compared to the control group. Hepatic superoxide dismutase and catalase activities and antioxidant capacity against peroxyl radical levels were also higher in fish experimentally infected by P. aeruginosa compared to the control group. Dietary supplementation with 300â¯mg/kg GPF prevented all alterations elicited by P. aeruginosa, with the exception of protein carbonylation levels. The dietary supplementation with 150â¯mg/kg GPF was not able to avoid alteration of the analyzed variables, being results similar to those infected (positive control). Based on these results, dietary supplementation with 300â¯mg/kg GPF prevented P. aeruginosa-induced liver damage in grass carp, and this protective effect occurred through prevention on excessive ROS and NOx production, as well as via prevention of lipid damage. Moreover, 300â¯mg/kg GPF exerted its hepatoprotective effects by improving enzymatic and non-enzymatic antioxidant defense system. In summary, this supplementation can be an interesting approach to prevent P. aeruginosa-induced liver damage.