Bacterial Hemorrhagic Septicemia Research Articles

Susceptibility and host immune response comparison between Siniperca chuatsi and Siniperca scherzeri infected by Aeromonas veronii

The bacterial hemorrhagic septicemia caused by Aeromonas veronii is a highly contagious disease leading to high mortality in various aquatic animals, which has become one of the most serious diseases in mandarin fish, Siniperca chuatsi and Siniperca scherzeri. The difference of susceptibility and host immune response between S. chuatsi and S. scherzeri to A. veronii has not been revealed. In this study, the calculated LD50 of A. veronii SJ4 to S. chuatsi and S. scherzeri was 3.8 × 105 CFU/ mL and 4.8 × 106 CFU/mL, respectively, indicating S. chuatsi displays more susceptible to A. veronii than S. scherzeri. The differences of immune response between S. chuatsi and S. scherzeri infected by A. veronii SJ4 was analyzed by transcriptome technology. A total of 6010 and 1676 differentially expressed genes (DEGs) of kidneys were detected in the S. scherzeri experimental group (S-S-E/C) and S. chuatsi experimental group (S-C-E/C) at the 12 hpi, respectively. GO and KEGG functional analysis of DEGs indicated that numerous enriched immune terms were mainly related to antigen processing and presentation, toll-like receptor signaling, and C-type lectin receptor signaling. 8 DEGs (CLE, HSP90, IL6, MHC I, MHC II, RAS, TLR5 and TLR9) were selected from these immune related pathways, and the spatiotemporal expression of these DEGs in S. chuatsi and S. scherzeri were evaluated and compared. The results showed that CLE, HSP90, IL6, MHC I, MHC II, RAS, TLR5 and TLR9 in S. scherzeri after A. veronii infection were significantly up-regulated than in S. chuatsi. Our results indicated that these immune-related genes may exert a pivotal role during the initial phase of infection, and the priming speed of these immune-related genes lead to the differences in host immunity. This study screened the potential genes and pathways which involved in the immune response of mandarin fish, which helps for further understanding on fish immune. By selecting immune-related genes and comparing the immune mechanisms of S. chuatsi and S. scherzeri at the transcriptome level, the research offers new insights for the genetic breeding of Siniperca species to enhance infection resistance.

Evaluation of the effectiveness of the use of a complex of antibacterial drugs for the treatment of bacterial hemorrhagic septicemia in fish

The aim of the study was to develop therapeutic measures to combat bacterial hemorrhagic septicemia of fish using a complex of antibacterial drugs “Levofloxacin” and “Chlortetracycline”.Methods used: experiments were carried out in aquarium conditions on juvenile carp and hybrids «Siberian sturgeon×Kaluga» (hereinafter hybrid SO×K) infected with a mixed culture of pathogens: highly pathogenic strains of Aeromonas sp., strains of R.R. Acinetobacter and Citrobacter. In the experiment, 2 variants of the use of antibiotics for a course of 7 days were tested. Bacteriological seeding of fish parenchymal organ samples was carried out on nutrient and differential diagnostic media.Novelty: it consists in working out the scheme of application for fish of a complex of new antibiotics for aquaculture.Results: the results of the evaluation of the therapeutic effect of antibiotics “Levofloxacin” + “Chlortetracycline” in the treatment of bacterial hemorrhagic septicemia are presented. The cessation of fish death was noted the next day after the start of therapy. Positive results were obtained in carp — with a combination of levofloxacin at a dosage of 1000 mg/kg of ichthyomass and chlortetracycline — 100 mg/kg of ichthyomass, in a hybrid of SO×K — 500 mg/kg of ichthyomass of levofloxacin + 200 mg/kg of ichthyomass of chlortetracycline. Evaluation of their combinations with different dosages did not show 100% effect. The difficulties of therapy have been identified, which are associated with the spread of strains of microorganisms resistant to antibacterial drugs.Practical significance: the developed method of therapy is effective, reduces the damage from the disease and can be recommended when developing measures to combat bacterial hemorrhagic septicemia in fish in aquaculture.

Characterization of atypical pathogenic Aeromonas salmonicida isolated from a diseased Siberian sturgeon (Acipenser baerii)

Acipenser baerii (Siberian sturgeon) is native to Kazakhstan and is currently endangered and is listed within the first class of protected animals. Sturgeon aquaculture is becoming an important tool for the recovery of this endangered species. Nonetheless, diseases involving typical symptoms of skin ulceration and systemic bacterial hemorrhagic septicemia have occurred in cultured A. baerii on a fish farm located in Western Kazakhstan. In this study, an infectious strain of bacteria isolated from an ulcer of diseased A. baerii was identified as Aeromonas salmonicida (strain AB001). This identification involved analyses of 16S rRNA, gyrB, rpoD, and flaA genes’ sequences. Even though strain AB001 belongs to A. salmonicida, it exhibited noticeable mobility and growth at temperatures of ≥37 °C. Profiling of virulence genes uncovered the presence of seven such genes related to pathogenicity. Antibiotic sensitivity testing showed that the strain is sensitive to aminoglycosides, amphenicols, nitrofurans, quinolones, and tetracyclines. Half-lethal doses (LD50) of strain AB001 for Oreochromis mossambicus and A. baerii were determined: respectively 1.7 × 108 and 7.2 × 107 colony-forming units per mL. The experimentally induced infection revealed that strain AB001 causes considerable histological lesions in O. mossambicus, including tissue degeneration, necrosis, and hemorrhages of varied severity.

Бактерии р. Bacillus – антагонисты патогенов аквакультуры

Due to the increasing resistance of aquaculture pathogens to antibiotics, the search for new approaches to the control of infectious diseases is of particular importance. A promising approach is the development of probiotic preparations based on antagonist bacteria. The paper studied the antagonistic activity of Bacillus strains that are promising for developing probiotics for fish. The strains were isolated from the bottom sediments of the Don River in the area of the Donskoy Fish Reserve, as well as from the intestines of cyprinids of natural populations, namely, from silver carp (Cyprinus gibelio), roach (Rutilus heckelii), and bream (Abramis brama). The inhibitory effect of Bacillus strains against causative agents of aeromonosis, pseudomonosis and bacterial hemorrhagic septicemia was studied by the method of delayed antagonism. Aeromonas and Pseudomonas species pathogenic for fish were isolated from sturgeons, cyprinids and salmons grown in pond farms and recirculating aquaculture systems in the Krasnodar Region, Rostov Region and the Republic of Adygea. It has been shown that sensitivity to the action of bacilli is not only a species, but also a strain-specific trait among bacterial pathogens of fish. Five strains were identified that exhibited the maximum antagonistic activity against the studied pathogens, and their species identification was carried out by molecular biological and mass spectrometric methods. It has been established that the most pronounced antagonism is exhibited by strains of bacilli isolated from bottom sediments. The growth of all studied strains of fish pathogenic species of Pseudomonas was suppressed only the B. subtilis R4 strain. Thus, strains of aerobic spore-forming bacteria suitable for the creation of probiotic preparations for aquaculture objects have been isolated and characterized.

Evolution of bacterial pathogens of fish and ways to preserve ecosystems

During the study period from 1979 to 2014 .a retrospective analysis of changes in the species composition of the bacterial flora of fish and water was carried out in connection with the transition from pond fish cultivation technology to industrial methods. Studies to determine the composition of the microflora of fish and microbiocenosis of water were carried out in various fish farms (Konakovsky Commercial sturgeon Breeding Plant, sturgeon commodity farm of LLC «BioAcustic», Novomichurinsky fish farm, Mozhaisk industrial and Experimental fish farm). The analysis of the ratio of aeromonads and opportunistic microflora in the etiology of bacterial hemorrhagic septicemia of fish was carried out. When studying the microbiocenosis of salmon and sturgeon fish, the predominance of anaerobic aeromonads and non-fermenting alkali-forming agents was established. When analyzing the microbiocenosis of water, a high level of the total microbial number was established. In the studied water samples, bacteria of the Escherichia coli group, aeromonads, acinetobacteria, moraxella, proteus and myxobacteria were detected.

ISOLATION OF STRAINS ANTAGONISTIC TO PATHOGENIC AEROMONADS FROM NATURAL POPULATIONS OF FISH AND BOTTOM SEDIMENTS

Increasing production efficiency and ensuring the environmental safety of commercial fish farming facilities through the creation of modern preparations for the treatment and prevention of diseases is a topical area of aquaculture. The study of the current situation shows that the factors limiting the possibilities of sustainable entry to the market, providing fish farms with high-quality highly productive breeding material and increasing the volume of commercial fish farming products are diseases of the breeding facilities. The development of new highly effective probiotic preparations for the prevention and treatment of aquaculture facilities will not only reduce the economic costs associated with the death of breeded fish, but will also help to increase the viability of fish, the accumulation of nutrients in tissues, and the correction of the microbiocenosis of the aquatic environment. The aim of the study is to search for natural Bacillus antagonistic strains promising for creating probiotics. The strains were isolated from bottom sediments and cyprinids of natural populations. In the course of the work, the antimicrobial spectrum of action of bacilli against the causative agents of aeromonosis, furunculosis and bacterial hemorrhagic septicemia (BHS) was studied. Aeromonas test-strains were isolated from sterlet, sturgeon, stellate sturgeon, trout, carp, grass carp, silver carp, grown in conditions of pond farms.

A mixed Bacillus gibsonii and Sphingomonas echinoides infection in cultured rainbow trout (Oncorhynchus mykiss)

Rainbow trout (Oncorhynchus mykiss) is a fish species with a long history of cultivation and bacterial pathogens are limiting the success rate. The aim of this study is the biochemical and molecular identification of two opportunistic pathogens detected in the rainbow trout cultured in net cages in a dam lake located on the Kızılırmak river; revealing the pathological symptoms of them in the moribund fish samples; determination of their antimicrobial susceptibility profile and determination of the antagonistic effect of two probiotic-candidate strains against them. Depending on the results of the conventional bacteriologic and molecular identification studies, bacterial isolates recovered from the internal organs of the moribund fish samples, a mixed bacterial infection case of Bacillus gibsonii and Sphingomonas echinoides was identified in the moribund fish samples showing general bacterial hemorrhagic septicemia symptoms for the first time in rainbow trout. Despite it was not possible to identify these isolates at the species level using conventional bacteriological methods, our isolates separately showed similarities more than 99% with the above mentioned species in the 16s RNA sequence analysis. The results of this study showed that, long term water quality parameter determination and bacterial distribution monitoring studies which include molecular tools should be carried out in the aquaculture sites to increase the success in trout culture.

Peculiarities of the course of bacterial diseases of rainbow trut in industrial farms of North-West Russia

Currently, in the Leningrad Region and the Republic of Karelia, trout farming is carried out mainly in cage farms, and in recent years, small closed water supply units (RAS) are gaining popularity and are actively used. In the first years of operation, outbreaks of serious infectious diseases occurring in the form of bacterial hemorrhagic septicemia, as well as toxicosis, were observed in such installations. In cage farms, a joint course of bacterial and parasitic diseases is possible. In the course of the work, 11 cage farms in the Leningrad Region and the Republic of Karelia were surveyed, as well as 4 RAS in the Gatchinsky and Luga Districts of the Leningrad Region. The manifestation of aeromonas bacterial and infection and trienophorosis in the cage farm was associated with the growing conditions — high water temperatures, lack of feeding, and the presence of a formed focus of invasion in the water source. In the spring-summer and summer-autumn periods in cage farms, the manifestation of myxobacteriosis caused by Flavobacterium psychrichila is possible. In summer, the danger is a bacterial infection proceeding as a bacterial hemorrhagic septicemia (pathogens — Yersenia ruckeri and Flexibacter columnaris). In autumn, outbreaks of pseudomonosis are possible in cage farms. The causative agent is Pseudomonas fluorescens. However, it is also possible to find Pseudomonas putida, which is more characteristic of cyprinids. In the RAS, the death of fish was caused by mixed infections. The causative agents are Yersenia ruckeri and Carnobacterium piscicola; bacteria of the genera Flavobacterium and Aeromonas. Such a complex of aeromonads with flavobacteria is characterized by increased aggressiveness and can cause a serious septic infection. Timely measures taken, including the normalization of housing and feeding conditions, as well as therapeutic and prophylactic measures, made it possible to suppress the development of infections, toxicosis and improve the condition of fish on these farms.

Metabolomics and lipidomics analyses delineating Hfq deletion- induced metabolic alterations in Vibrio alginolyticus

Vibrio alginolyticus, a Gram-negative halophilic zoonotic pathogen, can cause bacterial hemorrhagic septicemia in various aquaculture species and wound infections in humans. V. alginolyticus brings about huge economic losses in aquaculture all around the world. Hfq, a ubiquitous RNA-binding protein, is a global post-transcriptional regulator in most bacteria and some archaea, by facilitating base-pairing between sRNAs and their mRNA targets, and is essential for adaptation to different environments and growth conditions. Despite its important roles in the stress adaptation, virulence, nutrient utilization, and colony morphology in V. alginolyticus, further research is required to shed light on the pathways modulated by Hfq. In this study, we used metabolomics and lipidomics analytical approaches based on ultrahigh-performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) to understand the impact of Hfq on the metabolic profile of V. alginolyticus. The deletion of the hfq gene resulted in the growth deficiency and cell elongation of V. alginolyticus cultured in the rich medium. Substantial metabolic alterations, mainly involved in amino acids, nucleotides, fatty acids, and lipids, were observed in the hfq deletion mutant strain (Δhfq) when compared to the wild-type (WT) strain and its complemented strain (hfq+). Notably, the hfq deletion induced accumulations of free fatty acids (FFAs) and nucleotides, but decreased levels of most amino acids (e.g., branched amino acids, aromatic amino acids, and aspartate family amino acids). Meanwhile, the majority of lipids (e.g., lysophosphatidylglycerol, lysophosphatidylethanolamine, phosphatidylcholine, phosphatidic acid, cardiolipin, sphingomyelin, some phosphatidylglycerol and phosphatidylethanolamine with mono- or poly-unsaturated fatty acids) were decreased, while ceramide, diacylglycerol, triacylglycerol and some phosphatidylglycerol and phosphatidylethanolamine with saturated fatty acids increased in the Δhfq strain. These data demonstrated that the hfq deletion triggered de novo synthesis of FFAs and nucleosides and enhanced the catabolism of phospholipid and sphingomyelin to further regulate cell division and growth. Additionally, the hfq deletion could inhibit the synthesis of the branched amino acids, aromatic amino acids and enhance the TCA cycle to influence cell stress defenses and energy metabolism. Our research indicates that Hfq can regulate pathways associated with cell division, growth and stress resistance, being an important metabolic modulator in V. alginolyticus.

A Mixed Frigoribacterium faeni and Lactococcus garvieae Infection in Cultured Rainbow Trout (O. mykiss)

The aim of this study was to diagnose the bacterial pathogens of moribund rainbow trout (Oncorhynchus mykiss) reared in a dam-lake cage farm located in the Black Sea Region of Turkey and to determine their antibiotic susceptibility and histopathological effects by using routine bacteriological, histopathological and molecular methods. Besides possibility of the use of two probiotics against these pathogens for the prevention of further infections was investigated. In this study, a mixed bacterial infection case caused by Frigoribacterium faeni and Lactococcus garvieae was diagnosed in rainbow trout samples of 100-250 g with general clinical and histopathological symptoms of bacterial hemorrhagic septicemia. Pathogens were found to be resistant against most of the antibiotics tested and the possibility of the use of Bacillus subtilis as a probiotic to prevent diseases caused by these pathogens was proposed.

Forms of bacterial hemorrhagic septicemia course in fisheries of the North Caucasus regions

Summary. Bacterial hemorrhagic septicemia of fish is widespread in the Russian Federation, including in the regions of the North Caucasus. Clinically, the disease is manifested by the presence of separate serous-hemorrhagic sites on the skin, usually in the head and abdomen, inflammation of the fins, ulcerations (abscesses) on the skin, ascites and occasionally protrusion of the anus. The etiological structure of bacterial hemorrhagic septicemia of fish includes a wide range of pathogens belonging to both the Aeromonadaceae family and bacteria of other families: Pseudomonadaceae, Enterobacteriaceae, Streptococcaceae, Bacillaceae, Staphylococccaceae, Moraxellaceae, Flavobacteriaceae, Microavocacteriaceae, Microavocactaeceae. The main causative agents of bacterial hemorrhagic septicemia of fish are opportunistic bacteria of the genus Aeromonas. This disease can occur in three forms: acute, subacute and chronic. The form of the course of bacterial hemorrhagic septicemia of fish depends on the temperature of the water, the species of the fish, the contamination of the reservoir, the amount of oxygen, the density of fish and other factors that reduce the resistance of the fish organism. The incubation period of bacterial hemorrhagic septicemia of fish on average lasts from three to thirty days. Bacterial hemorrhagic septicemia of fish most often occurs in the form of endogenous autoinfection, which is caused by weakly virulent pathogens located in the body of fish - representatives of the normal intestinal microflora. At the acute form of the disease, the death of fish reaches 90-100%, at subacute - up to 75%. The climatic conditions of the regions of the North Caucasus - high year-round water temperature, sharp fluctuations in the temperature of water and air in the winter-spring and autumn-winter periods contribute to the spread of bacterial hemorrhagic septicemia of fish in natural waters.

Этиологическое значение аэромонад различных видов при бактериальной геморрагической септицемии (БГС) карпов

Этиологическое значение аэромонад различных видов при бактериальной геморрагической септицемии (БГС) карпов

Comparative proteomic analysis of sensitive and multi-drug resistant Aeromonas hydrophila isolated from diseased fish

Bacterial hemorrhagic septicemia caused by multi-drug resistant (MDR) Aeromonas hydrophila has exponentially increased in the past decade, and reached an alarming rate making it a major concern in the aquaculture industry in China. The aim of this study was to investigate the difference in the regulation of proteins expression in multi-drug resistance and susceptible A. hydrophila strains isolated from diseased fish using two-dimensional electrophoresis (2-DE) combined with mass spectrometry. 28 isolates of A. hydrophila were successfully identified by biochemical tests. Antibiotic susceptibility test results showed that all the isolates have different drug resistant patterns. A total of 61 and 17 differently expressed proteins were identified in MDR and susceptible A. hydrophila, respectively, evidencing that biological processes related to carbon metabolism, biosynthesis of secondary metabolites, microbial metabolism in diverse environments, cationic antimicrobial peptide (CAMP) resistance and propanoate metabolism were down-regulated in MDR strain, while proteins involved in biosynthesis of antibiotics, glycolysis/gluconeogenesis were highly expressed in the sensitive strain. The analysis of differentially expressed proteins from multi-drug resistance and susceptible strains suggests that a number of proteins are involved in several metabolic metabolism pathways plays an important role in A. hydrophila drug resistance. Our findings provide new insights about mechanisms involved in drug resistance and propose possible novel targets for developing alternative antibacterial drugs.

Molecular characteristics, pathogenicity and medication regimen of Aeromonas hydrophila isolated from common carp (Cyprinus carpio L.).

Aeromonas hydrophila causes disease in fish known as Motile Aeromonas Septicemia (MAS), also named as bacterial hemorrhagic septicemia. In this study, a pathogenic A. hydrophila strain was isolated from common carp Cyprinus carpio L., which were suffering from severe hemorrhagic septicemia. According to the phylogenetic analysis derived from 16S rDNA sequence, the isolate formed a single branch in the A. hydrophila group, named AhHN1. Artificial infection results indicated that AhHN1 showed strong pathogenicity in C. carpio and the LD50 was 1.38 × 106 CFU/fish, the clinical symptoms and pathological features of infected fish were similar to those observed in natural infections. The antimicrobial susceptibility testing revealed that AhHN1 resistance to more than 13 kinds of antimicrobial agents. However, the AhHN1 strain exhibited an extremely sensitivity to enrofloxacin, the in vitro activities of enrofloxacin were subsequently investigated and drug selection window (MSW) was 0.0016–0.0125 µg/ml. Pharmacokinetics data showed that plasma concentration of enrofloxacin was 0.0016, 0.0148 and 0.0282 µg/ml at 24 hr after orally administered with 2.5, 5 and 10 mg/kg enrofloxacin. Moreover, dosing once a day of 2.5, 5 and 10 mg/kg enrofloxacin, which the relative protection ratio (RPS) was amounted to 33.3, 66.7, and 83.3%, respectively. Therefore, 5 mg/kg enrofloxacin was considered to be the rational regimen for controlling AhHN1 infection in C. carpio in the countries where the use of enrofloxacin is permitted in aquaculture. The aim of this study was to establish a scientific medication regimen for the prevention and therapy of the mutidrug-resistant A. hydrophila infection.

Pathogenesis and pathological analysis of Edwardsiella tarda from Dabry's sturgeon (Acipenser dabryanus) in China

Dabry's sturgeon (Acipenser dabryanus) is designated as critically endangered in the IUCN Red List and a first-class protected animal in China. Recently, A. dabryanus in a fishery institute in southwestern China suffered from a high rate of mortality (~70%). This study confirmed the etiology of moribund A. dabryanus. Bacteria isolated from heart, liver, gill and intestine samples of infected fish were identified via biochemical characterization and molecular analysis. A phylogenetic tree generated from 16S rDNA sequences revealed that one isolate, designated strain EA, had the basic characteristics of Edwardsiella tarda, the causative agent of bacterial hemorrhagic septicemia in fish. Moreover, we detected six virulence genes (citC, fimA, gadB, katB, mukF and gyrB) in strain EA; however, none possessed the esrB gene. Virulence tests were conducted by injecting EA (1.0 × 106 CFU/g fish) into healthy fish, and the results demonstrated that EA was lethal to A. dabryanus, with a mortality rate of 88% (7/8). The challenged fish showed similar clinical symptoms to those that were naturally infected. To our knowledge, this is the first report of E. tarda infection associated with mass mortality in A. dabryanus. The results from this study elucidate the pathogenesis and severe pathogenicity that E. tarda in farmed A. dabryanus and highlight the need for appropriate disease control and prevention measures.

Antimicrobial resistance prevalence of Aeromonas hydrophila isolates from motile Aeromonas septicemia disease

Fish suffer, from bacteria, fungi, virus and parasites or by physical ailments. Gurami (Osphronemus gouramy), nila (Oreochromis niloticus), carp (Cyprinus carpio), catfish (Clarias sp.) were the most reported infections caused by Aeromonas are bacterial hemorrhagic septicemia or Motile Aeromonas Septicemia (MAS). Antibiotics are drugs of natural or synthetic origin that have the capacity to kill or to inhibit the growth of micro-organisms included MAS. However, the use of antibiotics in the long term can cause negative impacts, among others, feared the occurrence of bacterial resistance in certain antibiotics. The results showed five of isolates were sensitive to antibiotics of chloramphenicol, gentamycin, oxytetracycline, cefradoxil and nalidixic acid but resistant to vancomycin colistin sulphate, rifampisin, cephalosporin and novobiocin.

Fungal Diseases of Fish: A Review

Now a day, fishes are used for biomedical researches along with use as a food also. Chemical contaminants of marine environments are of momentous concern. Similar to other flora and fauna, fish can also be ill with various types of diseases. Freshwater fishes are an important protein source for people of many countries. Fish farming in various parts of the world has increased many folds in the last decade. Bacterial hemorrhagic septicemia, lernaeasis, saprolegniasis and anoxia are the most frequently occurring fish diseases in pond fishes. Fungal infections are among the most general diseases seen in temperate fish. Water moulds infections cause losses of freshwater fishes and their eggs in both natural and commercial fish farms. Although, infection as a result of microbial contamination does not frequently result in disease but ecological stress may upset the balance between the probable pathogens and their hosts. Prevention is, as always, the best medicine. Most infe ctions can be successfully treated if caught early.

Isolation, phenotypic and molecular characterization of motile Aeromonas species, the cause of bacterial hemorrhagic septicemia in affected farmed carp in Iran

Background: Motile Aeromonas species cause heavymortalities in carp farms during spring and summer in Iran. Objectives: The aim of this study was to detect phenotypicand genotypic characterization of motile Aeromonas species isolated fromdiseased carps in some northern and southern provinces of Iran. Methods: A number of 40 samples from 22 fish farms werecollected. The identified motile Aeromonas species were sequenced andphylogenetic tree was drawn by MEGA6 using UPGMA analysis. Results: A number of 19 bacterial isolates wereidentified as motile Aeromonas sp. by biochemical tests, and the DNAsegments of 16S rRNA gene of all these strains gave 1200 bp after running on 1%agarose electrophorus gel. Also, the sequencing results showed that thebacterial samples were determined as A. hydrophila and A. veroniibiovar veronii. Conclusions: Phylogenetic analysis revealed that motile Aeromonasstrains in this study were separated in two clusters and four genogroups with high similarities

Investigation on the Bacterial Haemorrhagic Septicemia Disease of Cyprinus carpio and Channa striatus

Bacterial Hemorrhagic Septicemia (BHS) was found affecting Cyprinus carpio and Channa striatus. Bacteriological examination and artificial infection trials were carried out on these fishes. Hematological examination showed substantial decline in the number of erythrocytes and lymphocytes, increase in the number of granulocytes and significant loss in the amount of hemoglobin. Histopathological examination suggested that the affected part of the skin had got completely destroyed. The peripheral area of the liver showed loosening of tissue and cell distension. There was complete shrinkage in all the components of kidney and glomeruli appeared smaller in size than healthy ones. Artificially infected specimens of C. carpio and C. striatus were treated with 20 ppm and 30 ppm chloramphenicol solution and oxytetracycline @ 50 and 60 mg/kg of feed for 20 and 30 days respectively. The results of this work indicated that Aeromonas hydrophila and Pseudomonas fluorescens were the etiological agents for this disease.

Kazal-type proteinase inhibitor from disk abalone (Haliotis discus discus): Molecular characterization and transcriptional response upon immune stimulation

Proteinases and proteinase inhibitors are involved in several biological and physiological processes in all multicellular organisms. Proteinase inhibitors play a key role in regulating the activity of the respective proteinases. Among serine proteinase inhibitors, kazal-type proteinase inhibitors (KPIs) are widely found in mammals, avians, and a variety of invertebrates. In this study, we describe the identification of a kazal-type serine proteinase inhibitor (Ab-KPI) from the disk abalone, Haliotis discus discus, which is presumably involved in innate immunity. The full-length cDNA of Ab-KPI includes 600 bp nucleotides with an open reading frame (ORF) encoding a polypeptide of 143 amino acids. The deduced amino acid sequence of Ab-KPI contains a putative 17-amino acid signal peptide and two tandem kazal domains with high similarity to other kazal-type SPIs. Each kazal domain consists of reactive site (P1) residue containing a leucine (L), and a threonine (T) located in the second amino acid position after the second conserved cysteine of each domain. Temporal expression of Ab-KPI was assessed by real time quantitative PCR in hemocytes and mantle tissue following bacterial and viral hemorrhagic septicemia virus (VHSV) challenge, and tissue injury. At 6 h post-bacterial and -VHSV challenge, Ab-KPI expression in hemocytes was increased 14-fold and 4-fold, respectively, compared to control samples. The highest up-regulations upon tissue injury were shown at 9 h and 12 h in hemocytes and mantle, respectively. The transcriptional modulation of Ab-KPI following bacterial and viral challenges and tissue injury indicates that it might be involved in immune defense as well as wound healing process in abalone.