Serum Agglutinating Antibody Research Articles

Brucellosis outbreak in a remote village in northwestern Tajikistan in 2023: a matched case-control study.

A sharp increase in reported brucellosis incidence was observed in northwestern Tajikistan (from 1.0/100,000 people in January-May 2022 to 32.7/100,000 in January-May 2023). Most (82%) cases were from the same remote mountainous village (population = 10,712). The aim of this study was to identify risk factors for brucellosis infection and mitigate disease risk. Using a case-control design, we conducted face-to-face interviews and collected blood samples during May-June 2023. Fifty-seven cases and 114 controls were recruited. Cases were the first person in a household diagnosed with brucellosis during February-June 2023 with positive serum agglutination test and antibody titers ≥1/160 from blood samples. Two controls were selected for each case (neighbors from different households matched by age and sex). Controls testing positive were excluded and replaced. We conducted conditional multivariable logistic regression to calculate adjusted odds ratio (AOR) and 95% confidence intervals (CI). Among the 87 brucellosis patients reported, 57 (66%) agreed to participate and didn't have secondary cases in the household. Of the 57 cases, 68% were 15-44 years old, and 44% were male. Cases peaked in May 2023. Common symptoms were joint pain (95%), fever (84%), weakness (72%), and night sweats (65%). Of selected controls, 13% tested positive and were excluded. All cases and 94% of controls owned livestock (mostly cattle, sheep, or goats); no animals had not been vaccinated in the past 5 years. Brucellosis was associated with consumption of both homemade kaymak (clotted cream) and home-raised meat compared with neither (AOR: 59 [95%CI: 4.3-798], p < 0.01), home-raised meat but not kaymak compared with neither (AOR: 54 [4.0-731], p < 0.01), and involvement in animal slaughter compared with no involvement (AOR: 36 [2.8-461], p < 0.01). Contact with unvaccinated livestock or consumption of their products was a key contributor to this outbreak in a remote village of Tajikistan. With 13% of controls testing positive, true incidence was likely greater than reported. Following our investigation, a brucellosis awareness education campaign and animal vaccination campaigns were carried out in the region and only one case was reported in September 2023.

Evaluation of the efficacy of a novel Vibrio vulnificus vaccine based on antibacterial peptide inactivation in turbot, Scophthalmus maximus

Tongue sole tissue factor pathway inhibitor 2 (TFPI-2) C-terminus derived peptide, TC38, has previously been shown to kill Vibrio vulnificus cells without lysing the cell membrane; thus, the remaining bacterial shell has potential application as an inactivated vaccine. Therefore, this study aimed to evaluate the immune response induced by the novel V. vulnificus vaccine. The protective potential of TC38-killed V. vulnificus cells (TKC) was examined in a turbot model. Fish were intramuscularly vaccinated with TKC or FKC (formalin-killed V. vulnificus cells) and challenged with a lethal-dose of V. vulnificus. The results showed that compared with FKC, TKC was effective in protecting fish against V. vulnificus infection, with relative percent of survival (RPS) rates of 53.29% and 63.64%, respectively. The immunological analysis revealed that compared with the FKC and control groups, the TKC group exhibited: 1) significantly higher respiratory burst ability and bactericidal activity of macrophages at 7 d post-vaccination; 2) increased alkaline phosphatase, acid phosphatase, lysozyme, and total superoxide dismutase levels post-vaccination; 3) higher serum agglutinating antibody titer with corresponding higher serum bactericidal ability, and a more potent serum agglutination effect, as well as an increased IgM expression level; 4) higher expression of immune relevant genes, which were involved in both innate and adaptive immunity. Taken together, this is the first study to develop a novel V. vulnificus inactivated vaccine based on AMP inactivation, and TKC is an effective vaccine against V. vulnificus infection for aquaculture.

Immunogenicity study of OmpU subunit vaccine against Vibrio mimicus in yellow catfish, Pelteobagrus fulvidraco

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.

The efficiency of vaccination against cattle necrobacteriosis using an experimental vaccine with a new adjuvant complex

The purpose of the study was to analyze the effectiveness of the adjuvant complex based on saponin, glycerin and chitosan in the experimental series of an inactivated vaccine against cattle necrobacteriosis. 4 groups of animals (30 in each group) were selected for the study, aged 6 to 24 months. The first (1st) group consisted of calves 6 months old, the second (2nd) group consisted of animals 12 months old and the third group – animals 24 months old. The control 4 (fourth) group (non-vaccinated animals) contained 10 animals of each age group – 6, 12 and 24 months old. The animals were vaccinated using a needle-free injector at a dose of 0.4 cm3 in two points at a distance of 7–10 cm (0.2 cm3 each) twice at intervals of 4-6 weeks. Revaccinated after 6 months, with a single dose of 0.4 cm3 (at two points, 0.2 cm2 each). It was found that the vaccine with the multicomponent adjuvant had low viscosity and hardening temperature, moderate reactivity, high stability during storage, prolonged immunity in vaccinated animals. The immunity in animals was detected 21 days after the first vaccine administration and lasted at least 18 months after the last immunization. The necrobacteriosis incidence in animals of the control non-vaccinated group was 70-80%. During double vaccination, the average level of postvaccinal agglutinating antibodies in serum of experimental groups of animals was 312.08±74.12 – 62.13±69, 07. Humoral response in vaccinated animals provided reliable protection against Fusobacterium necrophorum disease within two years (observation period). Absence of disease symptoms in vaccinated animals during 2 years testified to the high preventive efficiency of the vaccine. The results obtained confirm the validity of the application of multicomponent adjuvant in inactivated sorbed vaccine as a means of specific prevention of animal necrobacteriosis.

Identification of fish source Vibrio alginolyticus and evaluation of its bacterial ghosts vaccine immune effects.

Vibrio alginolyticus (V. alginolyticus) is a common pathogen for humans and marine aquatic animals. Vibriosis of marine aquatic animals, caused by V. alginolyticus, has become more prevalent globally in recent years. Hence, a safe and effective vaccine is urgently needed for the control of this disease. Here, the strain 16‐3 isolated from the large yellow croaker (Larimichthys crocea) suffered from canker was identified as V. alginolyticus based on morphological, biochemical, and 16S rDNA sequencing analysis. Then, recombinant temperature‐controlled lysis plasmid pBV220‐lysisE was electroporated into the strain 16‐3 to generate V. alginolyticus bacterial ghosts (VaBGs) by inducing lysis gene E expression, and the safety and immune effects of VaBGs were further investigated in mice and large yellow croaker. The results showed that VaBGs were as safe as formalin‐killed V. alginolyticus cells (FKC) to mice and fish. Compared with FKC and PBS groups, significant elevations of the serum agglutinating antibody titer, serum bactericidal activity, lymphocyte proliferative responses, and levels of four different cytokines (Th1 type: IL‐2, TNF‐α; Th2 type: IL‐4 and IL‐6) in serum were detected in the VaBGs group, indicating that a Th1/Th2‐mediated mixed immune response was elicited by the VaBGs. More importantly, after challenged with the parent strain 16‐3, VaBGs‐vaccinated mice and fish showed higher protection than FKC‐vaccinated mice, the relative percent of survival (RPS) being 60%, 66.7% and 40%, respectively. Taken together, this is the first demonstration that the newly constructed V. alginolyticus ghosts may be developed as a safe and effective vaccine against V. alginolyticus infection in aquaculture.

Construction of Vibrio mimicus ghosts as a novel inactivated vaccine candidate and its protective efficacy against ascites disease in grass carps (Ctenopharyngodon idella)

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.

Combined or individual effects of dietary vitamin E and selenium nanoparticles on humoral immune status and serum parameters of rainbow trout (Oncorhynchus mykiss) under high stocking density

A 60day feeding experiment was conducted to evaluate the effects of dietary vitamin E (vit E), selenium nanoparticles (nanoSe), and their combination on humoral immune status and serum parameters of rainbow trout under high density condition. A total of 1275 rainbow trout with an average weight of 42.6±2.3g were acclimatized, distributed into 15 tanks and divided into five experimental groups according to stocking density and diet: Normal control (20kgm−3; basal diet), Dense control (80kgm−3; basal diet), Vit E (80kgm−3; 500mgkg−1 vit E-supplemented diet), NanoSe (80kgm−3; 1mgkg−1 nanoSe-supplemented diet), and Combination (80kgm−3; 500mgkg−1 vit E and 1mgkg−1 nanoSe-supplemented diet). Each group consisted of three tanks. High stocking density reduced weigh gain, specific growth rate, feed intake, feed conversion ratio, serum agglutination antibody titer, total antioxidant capacity, and globulin level, but increased lysozyme, albumin, and cholesterol levels when basal diet was fed. However, vit E supplementation to diets significantly improved growth performance and health status of rainbow trout. While the combination of nanoSe with vit E promoted the performance of the fish, supplementation with nanoSe had no significant effects on performance in rainbow trout under high density conditions, suggesting that the beneficial effects observed in the performance of the Combination group may be due to vitamin E alone.

Effects of dietary administration of guanosine monophosphate on the growth, digestibility, innate immune responses and stress resistance of juvenile red sea bream, Pagrus major

The present study explored the dietary administration effects of guanosine monophosphate (GMP) on growth, digestibility, innate immune responses and stress resistance of juvenile red sea bream, Pagrus major. A semi-purified basal diet supplemented with 0% (Control), 0.1% (GMP-0.1), 0.2% (GMP-0.2), 0.4% (GMP-0.4) and 0.8% (GMP-0.8) purified GMP to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish (mean initial weight 3.4 g) for 56 days. The obtained results clearly indicated that, growth performance of red sea bream enhanced by dietary GMP supplementation compared to control and significantly higher final weight was found in fish fed diet group GMP-0.4. Specific growth rate (SGR) and percent weight gain (%WG) also significantly higher in diet group GMP-0.4 in compared to control and it was not differed (P > 0.05) with diet group GMP-0.8. Feed intake significantly increased with the supplementation of GMP. Feed conversion efficiency (FCE) and protein efficiency ratio (PER) also improved (P < 0.05) when fish fed the diets containing GMP and diet group GMP-0.4 showed the significantly higher value in compared to control. The Apparent digestibility coefficients (dry matter, protein and lipid) also improved by GMP supplementation and the significantly higher protein digestibility was observed in fish fed diet groups GMP-0.2, GMP-0.4 and GMP-0.8. Among the measured non specific immune parameters peroxidase activity (PA), respiratory burst activity (NBT), Bactericidal activity (BA) were significantly affected by dietary supplementation and highest value obtained in diet group GMP-0.4. Total serum protein, lysozyme activity (LA), and agglutination antibody titer also increased (P > 0.05) by GMP supplementation. In contrast, catalase activity decreased with GMP supplementation. In terms of oxidative stress GMP-0.2 showed best condition with low oxidative stress and high antioxidant level. Moreover, the fish fed GMP supplemented diets had better improvement (P < 0.05) in body protein contents, hepatosomatic index, hematocrit content and glutamyl oxaloacetic transaminase (GOT) and glutamic-pyruvate transaminase (GPT) level than the control group. Supplementation also improved (P < 0.05) freshwater stress resistances. Quadratic regression analysis of WG and LA revealed that, the optimal levels of dietary GMP were 0.45 and 0.48%, respectively, for juvenile red sea bream, which is also in line with the most of the growth performance and health parameters of the fish.

Dietary effects of adenosine monophosphate to enhance growth, digestibility, innate immune responses and stress resistance of juvenile red sea bream, Pagrus major

Our study explored the dietary effects of adenosine monophosphate (AMP) to enhance growth, digestibility, innate immune responses and stress resistance of juvenile red sea bream. A semi-purified basal diet supplemented with 0% (Control), 0.1% (AMP-0.1), 0.2% (AMP-0.2), 0.4% (AMP-0.4) and 0.8% (AMP-0.8) purified AMP to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish (mean initial weight 3.4 g) for 56 days. The results indicated that dietary AMP supplements tended to improve growth performances. One of the best ones was found in diet group AMP-0.2, followed by diet groups AMP-0.1, AMP-0.4 and AMP-0.8. The Apparent digestibility coefficients (dry matter, protein and lipid) also improved by AMP supplementation and the significantly highest dry matter digestibility was observed in diet group AMP-0.2. Fish fed diet groups AMP-0.2 and AMP-0.4 had significantly higher peroxidase and bactericidal activities than fish fed the control diet. Nitro-blue-tetrazolium (NBT) activity was found to be significantly (P < 0.05) greater in fish fed diet groups AMP-0.4 and AMP-0.8. Total serum protein, lysozyme activity and agglutination antibody titer were also increased (P > 0.05) by dietary supplementation. In contrast, catalase activity decreased with AMP supplementation. Moreover, the fish fed AMP supplemented diets had better improvement (P < 0.05) in body lipid contents, condition factor, hematocrit content and glutamyl oxaloacetic transaminase (GOT) level than the control group. Supplementation also improved both freshwater and oxidative stress resistances. Interestingly, the fish fed diet groups AMP-0.2 and AMP-0.4 showed the least oxidative stress condition. Finally it is concluded that, dietary AMP supplementation enhanced the growth, digestibility, immune response and stress resistance of red sea bream. The regression analysis revealed that a dietary AMP supplementation between 0.2 and 0.4% supported weight gain and lysozyme activity as a marker of immune functions for red sea bream, which is also inline with the most of the growth and health performance parameters of fish under present experimental conditions.

Vaccination of Silver Sea Bream (Sparus sarba) against Vibrio alginolyticus: Protective Evaluation of Different Vaccinating Modalities.

In order to develop more effective immunological strategies to prevent vibriosis of farmed marine fish in Hong Kong and southern China, various vaccine preparations including formalin-, phenol-, chloroform- and heat-killed whole cell bacterins and subcellular lipopolysaccharides (LPS), as well as different administration routes, were investigated. Fish immunized with the subcellular LPS exhibited the best protection [Relative Percent of Survival (RPS) = 100], while fish immunized with whole cell bacterins displayed varying degrees of protection (RPS ranged from 28 to 80), in descending order: formalin-killed > phenol-killed > heat-killed > chloroform-killed bacterins. Regarding various administration routes, fish immunized with two intraperitoneal (i.p.) injections exhibited the best protection, and the RPS values were 100 or 85 upon higher or lower doses of pathogenic V. alginolyticus challenges. Both oral vaccination and a combination of injection/immersion trial were also effective, which achieved relatively high protection (the RPS values ranged from 45 to 64.3). However, two hyperosmotic immersions could not confer satisfactory protection, especially when fish were exposed to the severe pathogenic bacteria challenge. Marked elevations of serum agglutinating antibody titer were detected in all immunized fish. Macrophage phagocytosis was enhanced significantly, especially in the fish immunized by formalin- and phenol-killed bacterins through various administration routes. Both adaptive (specific antibody) and innate (phagocytic activity) immunity elicited by different immunization strategies were in parallel with the degree of protection offered by each of them. Although all vaccination trials had no significant effect on the serum hematocrit and hemoglobin levels, the circulating lymphocyte counts were significantly elevated in the fish immunized with LPS, formalin- and phenol-killed bacterins. Serum cortisol levels appeared to be reduced in all immunized fish except the trial of hyperosmotic immersion, which indicated the stressful impact on vaccinated fish.

Dietary fermentable fiber upregulated immune related genes expression, increased innate immune response and resistance of rainbow trout (Oncorhynchus mykiss) against Aeromonas hydrophila

This trial was carried out to investigate the effects of dietary administration of Vitacel®, a commercial fermentable fiber, on immune related genes (Lysozyme, TNFα and HSP70) expression, innate immune response and resistance of rainbow trout against Aeromonas hydrophila. 120 healthy rainbow trout (81.65 ± 1.49 g) were distributed in six fiberglass tanks assigned to two treatments. The treatments were feeding rainbow trout with diets supplemented with 0 (control) or 10 g kg−1 Vitacel® for 45 days. The results revealed that administration of fermentable fiber significantly (P < 0.05) upregulated lysozyme and TNFα gene expression. HSP70 gene expression was significantly lower in Vitacel® fed fish at the end of trial (P < 0.05). Furthermore dietary administrations of Vitacel® remarkably elevated rainbow trout innate immune parameters include serum lysozyme, ACH50, bactericidal activity and agglutination antibody titer (P < 0.05). Administration of 10 g kg−1 Vitacel® significantly increased rainbow trout resistance against A. hydrophila (P < 0.05). The results of present study revealed that dietary Vitacel® can upregulates immune related genes expression and elevates innate immune response and disease resistance of rainbow trout.

Proposed method for agglutinating antibody titer analysis and its use as indicator of acquired immunity in pacu, Piaractus mesopotamicus.

Antibody can be assessed by agglutinating antibody titer which is a quantitative measure of circulating antibodies in serum from fish previously immunized. The antibody evaluation has been performed with different fish species, and is considered a reliable method that can be applied to confirm several hypothesis regarding acquired immunity, even in conjunction with precise methods to describe immune mechanisms. In order to provide appropriate analytical methods for future studies on the specific immune system of native fish, the present study standardized on assay to measure the serum agglutinating antibody titer produced after immunization with inactivated A. hydrophila and levamisole administration in pacu. It was possible to determine the agglutinating antibodies titer in a satisfactorily way in pacu immunized with inactive A. hydrophila, and the highest titers were observed on fish fed with levamisole.

Enhancement of Eriobotrya japonica extracts on non-specific immune response and disease resistance in kelp grouper Epinephelus bruneus against Vibrio carchariae

The present study investigated the effect of Eriobotrya japonica extracts at 0%, 0.1%, 1.0%, and 2.0% doses supplementation with feed on non-specific immune response, hematological and biochemical profile, and disease resistance against Vibrio carchariae in kelp grouper Epinephelus bruneus at weeks 1, 2, and 4. The white blood cell (WBC) significantly increased in fish fed with 0.1%, 1.0%, and 2.0% diets on weeks 1 and 2 when compared to the control. However, the glucose always decreased from the control except on week 2 against pathogen. The serum total protein, albumin, and globulin significantly increased at week 2 but they did not changed significantly at weeks 1 and 4. The superoxide anion, lymphokines production index, and phogocytosis did not significantly increased in any diet on the first week whereas it was significantly enhanced in 1.0% and 2.0% supplementation diets on weeks 2 and 4 against V. carchariae when compared to control. All diets significantly enhanced the serum lysozyme activity, bactericidal activity, and haemolytic complement activity from weeks 1–4 as compared to control. The serum agglutinating antibody titre did not significantly enhance on the first week whereas it was significantly enhanced on weeks 2 and 4. Fish fed with 1.0% and 2.0% doses diets was found lower mortality than 0.1% diet. Thus, this study suggested that 1.0% and 2.0% doses supplementation diets could be advocated to enhance the immune response and production disease from V. carchariae in E. bruneus.

Serodiagnosis of Crohn's disease

Three serological tests, recommended as being of diagnostic value for Crohn's disease, were evaluated in 39 patients with Crohn's disease and--as controls--in 27 patients with ulcerative colitis, 45 healthy persons and 65 patients with inflammatory diseases other than Crohn's disease or ulcerative colitis. The tests were the determination of (1) serum antibodies to pseudomonas-like organisms (PLO) by means of indirect immunofluorescence; (2) agglutinating serum antibodies to 4 strains of anaerobic gram-positive coccoid rods (species of Eubacterium, Peptostreptococcus and Coprococcus); and (3) serum antibodies to perinuclear antigens in buccal mucosa of Crohn's disease patients by immunofluorescence. The results indicate that the occurrence of high-titer antibodies to PLO is reasonably sensitive for Crohn's disease, but has a low specificity, and that antibodies to perinuclear antigens in buccal mucosa have both low sensitivity and specificity. However, the occurrence of agglutinins to 4 strains of anaerobic grampositive coccoid rods is significantly higher in Crohn's disease than in ulcerative colitis, patients with other diseases and healthy controls. Thus the determination of these agglutinins does not discriminate between Crohn's disease and ulcerative colitis; but it is a serodiagnostic adjunct in the diagnosis of chronic inflammatory bowel diseases.

The immune response and protective efficacy of oral alginate microparticle Aeromonas sobria vaccine in soft-shelled turtles ( Trionyx sinensis)

Aeromonas sobria is an important bacterial pathogen of soft-shelled turtles ( Trionyx sinensis). The effect of an oral alginate microparticle A. sobria vaccine (MAV) on immune response and protection efficacy of soft-shelled turtles was investigated. The formalin-killed cultures of A. sobria strain Z-1 (FKC) were incorporated into alginate microparticles, and the encapsulated vaccine was orally used for immunizing turtles. The serum agglutinating antibody titers, bactericidal activity of blood leucocytes and relative percent survival (RPS) post-challenge with virulent live bacteria of control and immunized turtles were detected. The serum agglutinating antibody titers and bactericidal activity of the leucocytes in the turtles orally immunized with MAV reached a level equivalent to those of the turtles injected with FKC and were significantly higher than those of control group. The RPS of turtles immunized orally with the MAV and intraperitoneally with FKC was 89.5 and 94.7%, respectively, while 95% of the control turtles had died. These results demonstrated that oral alginate microparticle A. sobria vaccine was immunogenic, and could confer protective immunity in soft-shelled turtles.

The immune response and protective efficacy of vaccination with oral microparticle Aeromonas sobria vaccine in mice

The effect of an oral alginate microparticle Aeromonas sobria vaccine on immune response and protection of mice was investigated. The formalin-killed cultures (FKC) of A. sobria strain Z-1 treated with three methods were incorporated into alginate microparticles, and the encapsulated vaccines were orally used for immunizing mice. Four weeks after immunization, the serum agglutinating antibody titers, bactericidal activity of leucocytes and relative percent survival (RPS) of mice immunized orally with three microparticle vaccines were significantly higher than those of control mice. Among the immune efficacy of 3 microparticle vaccines, vaccine prepared directly from FKC (MVC) was the most, vaccine from FKC treated with freeze–melt method (MVCF) secondly, and vaccine from FKC treated with ultrasonic wave (MVCU) the worst. The serum agglutinating antibody titers and phagocytic activity of the blood monocytes in mice immunized orally with MVC reached a level equivalent to those of injection with FKC, and were significantly higher than those of control group. Moreover, from the 7th to 12th weeks, the serum agglutinating antibody titers in the MVC-immunized mice was significantly higher than those of injection with FKC. The RPS of mice immunized orally with MVC was 87.5%, while 100% of mice immunized orally with FKC and also the control mice died. These results demonstrated that oral alginate microparticle of A. sobria strain Z-1 was immunogenic and conferred protective immunity in mice, and could be used as a candidate vector system of oral vaccine of Aeromonas.

Modulation of the immune response to an Aeromonas hydrophila aroA live vaccine in rainbow trout: effect of culture media on the humoral immune response and complement consumption

The Aeromonas hydrophila aroA is an attenuated strain that has been assessed as a live vaccine in rainbow trout, Oncorhynchus mykiss. In this study the effects of different culture media used to grow the strain on its survival after in vitro exposure to rainbow trout serum, and on its immunogenicity in rainbow trout were compared. Four culture media were tested: Luria broth (LB), Luria broth with 0.25% glucose, trypticase soy broth (TSB), and brain–heart infusion broth (BHIB). Bacteria grown in culture media with glucose (TSB, BHIB and LB with 0.25% glucose) showed reduced complement consumption and a lower serum susceptibility. O. mykiss vaccinated with inocula prepared with BHIB- and LB-grown aroA cells resuspended in phosphate-buffered saline (PBS) showed higher and longer-lasting serum agglutinating antibody titres than those vaccinated with TSB-grown bacteria. Thus, a direct relationship between serum resistance and immunogenicity could not be established, but BHIB and LB culture media were the most effective in increasing the immunogenicity of the A. hydrophila aroA vaccine.

Evaluation of biofilm of Aeromonas hydrophila for oral vaccination of Clarias batrachus—a carnivore model

Biofilm of Aeromonas hydrophila was evaluated for oral vaccination of walking catfish ( Clarias batrachus L.). Fish were fed with fish paste incorporating biofilm (BF) or free cells (FC) of A. hydrophila for 20 days and monitored for serum antibody production up to 60 days post-vaccination. Serum agglutinating antibody titre and relative percent survival (RPS) following challenge were found to be significantly higher in catfish fed with BF vaccine compared to that with FC.

Duration of immunity in dogs vaccinated against leptospirosis with a bivalent inactivated vaccine

Duration of immunity in dogs induced with current commercial inactivated leptospirosis vaccines and evaluated against experimental infection, to date, has hardly been documented. The purpose of the present work was to assess the duration of immunity in dogs that is attainable with a commercial inactivated bivalent leptospirosis vaccine. For this purpose, young dogs were vaccinated twice followed by challenge with either Leptospira interrogans serovar canicola or L. interrogans serovar icterohaemorrhagiae 5 weeks, 27 weeks or 56 weeks after the second vaccination. For assessment of the duration of immunity, titres of agglutinating serum antibodies were measured before and after challenge, and the effects of challenge on a variety of parameters were determined including reisolation of challenge organisms from blood, urine and kidney. Both challenge strains induced a generalised infection in control dogs, the canicola strain being most virulent. From the results with different parameters it appeared that the two vaccinations induced a high rate of protection from generalised infection with canicola and icterohaemorrhagiae at 5, 27 and 56 weeks after the second vaccination. In addition, after 56 weeks, still a high level of immunity against renal infection with sv. canicola and, as a consequence, urinary shedding of sv. canicola bacteria, was demonstrated. It was, therefore, concluded that with this vaccine, using this vaccination schedule, a duration of immunity of 1 year can be attained against infection with both serovars.

The efficacy of lipopolysaccharide mixed chloroform-killed cell (LPS-CKC) bacterin of Pasteurella piscicida on Yellowtail, Seriola quinqueradiata

The effectiveness of the lipopolysaccharide-mixed chloroform-killed cell (LPS-CKC) vaccine against pasteurellosis was examined in yellowtail, Seriola quinqueradiata. Vaccination stimulated the production of serum agglutinating antibodies against Pasteurella piscicida. Production of a Superoxide anion, as determined by reduction of nitroblue tetrazolium (NBT), was increased in head kidney leucocytes of vaccinated fish. Fish vaccinated with the LPS-CKC bacterin showed a relative percentage survival (RPS) of 60% or greater when challenged by the immersion method using three different live P. piscicida strains and the efficacy of this bacterin continued for at least 35 days after vaccination. In addition to providing protection against an artificial challenge, the LPS-CKC bacterin also provided protection against natural infection by P. piscicida.