Long-term study of antibody response and injection-site effects of oil adjuvants in Atlantic halibut (Hippoglossus hippoglossus L)

Long-Term Protection Elicited by an Inactivated Vaccine Supplemented with a Water-Based Adjuvant against Infectious Hematopoietic Necrosis Virus in Rainbow Trout (Oncorhynchus mykiss)

Previous inactivated vaccines against infectious hematopoietic necrosis (IHN) usually had a strong early immune protective effect but failed to provide long-term protection in rainbow trout (Oncorhynchus mykiss). To find a method for stabilizing the desired protective effect of IHN vaccines, we assessed the immune enhancement effect of four adjuvants on formaldehyde inactivated vaccine for IHN at 60 days postvaccination (dpv). The efficacy of a two-dose vaccination with the candidate adjuvant-formaldehyde inactivated vaccine for IHN was evaluated in terms of early protection and long-term protection (30 to 285 dpv). Neutralizing antibody titers were also measured at each time point. The Montanide GEL 02 PR (Gel 02) adjuvant significantly enhanced the immune protection provided by the IHN inactivated vaccine, whereas the immune-boosting effect of the other tested adjuvants lacked statistical significance. Both tested Gel 02-adjuvanted IHN inactivated vaccine dosages had a strong immune protection effect within 2 months postvaccination, with a relative percent of survival (RPS) of 89.01% to 100%, and the higher dosage provided complete protection at 204 dpv and a RPS of 60.79% on 285 dpv by reducing viral titers in rainbow trout. The neutralizing antibodies were observed only in vaccinated fish on 30 and 60 dpv. Through compatibility with an appropriate adjuvant, the highly immune protective effect of an IHN inactivated vaccine was prolonged from 60 dpv to at least 284 dpv; this novel adjuvant-IHN inactivated vaccine has promise as a commercial vaccine that provides the best available and longest duration of protection against IHN to rainbow trout. IMPORTANCE Infectious hematopoietic necrosis virus (IHNV) is one of the most serious pathogens threatening the global salmon and trout industry. However, there is currently only one commercialized infectious hematopoietic necrosis (IHN) vaccine, and it is inadequate for solving the global IHN problem. In this study, a promising adjuvanted inactivated vaccine with long-term protection was developed and comprehensively studied. We confirmed the presence of a late antiviral response stage in vaccinated rainbow trout that lacked detectable neutralizing antibodies, which are commonly recognized to be responsible for long-term specific protection in mammals. These findings further our understanding of unique features of fish immune systems and could lead to improved prevention and control of fish diseases.

Efficacy of saponin-based inactivated rock bream iridovirus (RBIV) vaccine in rock bream (Oplegnathus fasciatus)

Rock bream iridovirus (RBIV) causes severe mortality in rock bream (Oplegnathus fasciatus) for last two decades. In view of this constant threat of RBIV to the rock bream industry, we conducted the present study with the aim to develop a safe and efficient remedial measure against the virus. In this study, we evaluated the safety and potentiality of squalene, aluminium hydroxide and saponin adjuvants, singly or in combinations, which can be used for developing an efficient inactivated (IV) vaccine to protect rock bream from RBIV infection. The evaluation results demonstrated that saponin (Sa) has the required potential in enacting the antiviral immune response in the host and in providing protection against virus mediated lethality, without causing any adverted side-effects. The study further, showed that a single primary dose of Sa-adjuvanted IV vaccine can confer moderate protections in short (60.04% relative percent mortality (RPS) at 4 wpv) and medium (53.38% RPS at 8 wpv) term post RBIV challenge; whereas, the same vaccine when administered in a prime-boost strategy, it resulted enhanced 93.34% RPS post virus challenge at 4 and 8 wpv. The moderate to high survivability demonstrated by the Sa-adjuvanted IV vaccine, was substantiated by the significant (p < 0.05) upregulation of IL-1β, Mx and PKR gene transcript. All surviving fish from the Sa-adjuvanted IV vaccine groups were strongly protected from re-infection with RBIV (1.1 × 10⁷) at 70 days post infection (dpi). In conclusion, it can be inferred that, Sa-adjuvanted IV RBIV vaccine can be an efficient control measure to protect the rock bream aquaculture industry against the lethal RBIV virus.

A single-step, high throughput, and highly reproducible method for measuring IgM quantity and avidity directly from fish serum via biolayer interferometry (BLI)

Quantification of specific antibody responses is critical in determining activation of MHCII-dependent immune memory and is generally performed by enzyme-linked immunosorbent assay (ELISA). Antibody avidity for a particular antigen is also informative of the quality of the adaptive immune response following vaccination. Avidity can be determined by chaotropic elution ELISA, pre-absorption ELISA, or surface plasmon resonance (SPR), although multimeric antibodies such as IgM are problematic for SPR. ELISA-based assays are very time consuming, require secondary antibody reagents, and are poorly repeatable. Here we demonstrate that biolayer interferometry (BLI) using an Octet HTX instrument can robustly and reproducibly quantify and determine avidity of specific IgM for an antigen directly from fish serum in a single step. We collected sera from giant grouper (Epinephelus lanceolatus) that had been vaccinated with the hapten 2,4-dinitrophenol conjugated to keyhole limpet hemocyanin (DNP-KLH) and from control fish injected with phosphate buffered saline. The specific IgM in the serum and its avidity for DNP were quantified via ELISA and BLI. BLI was precise and highly repeatable for determination of the quantity and avidity of antibody in the serum compared to ELISA. The wet-lab preparation and machine running time for BLI was 3-5 times faster than ELISA to generate the same amount of data. The ELISA inter-plate variation significantly affected reproducibility while BLI was consistent and repeatable between samples and plates. Indeed, the consistency of BLI data indicated that technical triplicates were redundant. Biological replication alone was sufficient to elucidate the effect of treatments. However, BLI required a lower serum dilution than ELISA for similar sensitivity, and thus more serum was required to produce high resolution data. BLI is an extremely high-throughput assay, providing teleost serum IgM quantification and avidity data as a single-step, agile alternative to ELISA.

Comparative study on antigen persistence and immunoprotective efficacy of intramuscular and intraperitoneal injections of squalene - aluminium hydroxide (Sq + Al) adjuvanted viral hemorrhagic septicaemia virus vaccine in olive flounder (Paralichthys olivaceus)

The profitability of the olive flounder (Paralichthys olivaceus) aquaculture industry in Korea depends on high production and maintenance of flesh quality, as consumers prefer to eat raw flounders from aquaria and relish the raw muscles as 'sashimi'. For sustaining high production, easy-to-deliver and efficient vaccination strategies against serious pathogens, such as viral hemorrhagic septicemia virus (VHSV), is very important as it cause considerable losses to the industry. Whereas, a safe and non-invasive vaccine formulation that is free from unacceptable side-effects and does not devalue the fish is needed to maintain flesh quality. We previously developed a squalene-aluminium hydroxide (Sq + Al) adjuvanted VHSV vaccine that conferred moderate to high protection in flounder, without causing any side effects when administered through the intraperitoneal (IP) injection route. However, farmers often demand intramuscular (IM) injection vaccines as they are relatively easy to administer in small fishes. Therefore, we administered the developed vaccine via IP and IM routes and investigated the safety and persistency of the vaccine at the injection site. In addition, we conducted a comparative analysis of vaccine efficacy and serum antibody response. The clinical and histological observation of the IM and IP groups showed that our vaccine remained persistence at the injection sites for 10-17 weeks post vaccination (wpv), without causing any adverse effects to the fish. The relative percentage of survival were 100% and 71.4% for the IP group and 88.9% and 92.3% for the IM group at 3 and 17 wpv, respectively. Thus, considering the persistency period (24 wpv) and both short and long-term efficacy of our vaccine, the present study offers an option to flounder farmers in selecting either IM or IP delivery strategy according to their cultured fish size and harvesting schedule - IM vaccination for small-sized fish and IP vaccination for table-sized fish.

Recombinant outer membrane protein OmpC induces protective immunity against Aeromonashydrophila infection in Labeorohita

Aeromonashydrophila is an opportunistic pathogen that causes enormous loss to aquaculture industry. The outer membrane proteins of Aeromonas help in bacterium-host interaction, and are considered to be potential vaccine candidates. In the present study, we evaluated immunogenicity and protective efficacy of recombinant OmpC (rOmpC) of A. hydrophila in Indian major carp, Labeorohita. The rOmpC-vaccinated fish produced specific anti-rOmpC antibodies with a significant antibody titer, and the antisera could specifically detect the rOmpC in the cell lysates of Escherichia coli expressing rOmpC and cross-react with different Aeromonas lysates, indicating the suitability of the anti-rOmpC antisera to detect Aeromonas infection. A significant increase was noted in ceruloplasmin level, myeloperoxidase and anti-protease activities in transient and temporal manner the sera of the rOmpC-immunized fish as compared to PBS-control fish. Higher agglutination- and hemolytic activity titers in the anti-rOmpC antisera indicate stimulation of innate immunity. Expression of immune-related genes comprising various acute phase proteins, cytokines and inflammatory response molecules were modulated in the head kidney of rOmpC-immunized L. rohita. While IgM, IL1β, and TLR-22 were significantly up-regulated at early time points (3 h-72 h), the others showed a transient augmentation at both early and later time points (SOD, lysozymes C and G, NKEF-B, C3, CXCa and TNF-α) in the rOmpC-immunized L. rohita in comparison to PBS-injected controls. These data suggest that the rOmpC-induced immune response is temporally regulated to confer immunity. In vivo challenge of the rOmpC-immunized fish with A. hydrophila showed significantly greater survival when compared to PBS-injected control fish. Thus, our results highlight the immunomodulatory role of rOmpC and demonstrate its protective efficacy in L. rohita, along with the use of anti-rOmpC antisera in detecting Aeromonas infections.

A CpG-riched plasmid as vaccine adjuvant reduce antigen dose of an inactivated Vibrio anguillarum vaccine in turbot (Scophthalmus maximus L.)

Inactivated vaccines are often applied with adjuvants in commercial fish farming. Although some mineral or non-mineral oil adjuvants show efficient improvement with inactivated vaccines, but sometimes bring side effects such as tissue adhesion and granulomatous lesion at the injection site. CpG ODN is a novel type of soluble adjuvant which has been proved to possess excellent advantages in fish vaccine development. In this study, we designed a tandem sequence of CpG ODN synthesized in plasmid pcDNA 3.1, and an inactivated Vibrio anguillarum vaccine developed in our previous work was chosen for determining the efficiency of the CpG-riched plasmids (pCpG) as an adjuvant. Results showed that pCpG we designed can offer higher immunoprotection with the vaccine. Interestingly, even below the minimum immune dosage of the vaccine, a high RPS of 84% was observed once the vaccine was administrated with the pCpG. Serum specific antibody titer, superoxide dismutase and total protein were enhanced and some immune genes related to both innate and adaptive immune response were upregulated, implying an effective auxiliary function of the pCpG. Totally, our study suggested that the pCpG is a potential and available adjuvant for turbot vaccine development.

Efficacy and safety of a non-mineral oil adjuvanted injectable vaccine for the protection of Atlantic salmon (Salmo salar L.) against Flavobacterium psychrophilum

Flavobacterium psychrophilum is the causative agent of Rainbow Trout Fry Syndrome which has had a major impact on global salmonid aquaculture. Recent outbreaks in Atlantic salmon in Scotland and Chile have added to the need for a vaccine to protect both salmon and trout. At present no licensed vaccines are available in Europe, leaving antibiotics as the only course of action to contain disease outbreaks. Outbreaks generally occur in fry at temperatures between 10 and 15 °C. Recently outbreaks in larger fish have given added impetus to the development of a vaccine which can provide long term protection from this highly heterogeneous pathogen. Most fish injectable vaccines are formulated with oil emulsion adjuvants to induce strong and long lasting immunity, but which are known to cause side effects. Alternative adjuvants are currently sought to minimise these adverse effects. The current study was performed to assess the efficacy of a polyvalent, whole cell vaccine containing formalin-inactivated F. psychrophilum to induce protective immunity in Atlantic salmon. The vaccine was formulated with an adjuvant containing squalene and aluminium hydroxide, and was compared to a vaccine formulated with a traditional oil adjuvant, Montanide ISA 760VG, and a non-adjuvanted vaccine. Duplicate groups of salmon (23.5 ± 6.8 g) were vaccinated with each of the vaccine formulations or phosphate buffered saline by intraperitoneal injection. Fish were challenged by intramuscular injection with F. psychrophilum six weeks post-vaccination to test the efficacy of the vaccines. Cumulative mortality reached 70% in the control salmon, while the groups of salmon that received vaccine had significantly lower mortality than the controls (p = 0.0001), with no significant difference in survival between vaccinated groups. The squalene/alum adjuvant was safe, more readily metabolised by the fish and induced less histopathological changes than the traditional oil adjuvant.

Studies on the antibody response and side effects after intramuscular and intraperitoneal injection of Atlantic lumpfish (Cyclopterus lumpus L.) with different oil-based vaccines

Atlantic lumpfish (Cyclopterus lumpus L.) is used as a biological delousing agent for sea lice (Lepeophtheirus salmonis K.) infestations in Norwegian aquaculture. Here, we present a study on the antibody response and vaccine side effects after intramuscular and intraperitoneal injection of lumpfish with two vaccines. Both vaccines contained bacterial antigens from atypical Aeromonas salmonicida A-layer types V and VI, Vibrio anguillarum serotype O1 and Moritella viscosa sp., but one vaccine contained a vegetable oil-based adjuvant, while the other contained a mineral oil-based adjuvant. Intramuscular injection of the mineral oil-based vaccine caused a high acute mortality of fish within 48 hr after immunization. Intraperitoneal injection of the mineral oil-based vaccine resulted in a lower severity of intra-abdominal side effects than the vegetable oil-based vaccine. Intramuscular injection of the mineral oil-based vaccine resulted in a significantly higher antibody response against A. salmonicida when compared to controls and the vegetable oil-based vaccine group. The antibody response was poor against V. anguillarum and M. viscosa for all groups. Our results indicate that intramuscular injection of oil-based vaccines might be feasible for providing immunological protection for Atlantic lumpfish against bacterial diseases, especially atypical A. salmonicida, but more work is required to identity optimal adjuvants.

A method to identify protein antigens of Dermanyssus gallinae for the protection of birds from poultry mites

The poultry red mite (PRM) Dermanyssus gallinae causes high economic losses and is among the most important parasites in poultry farming worldwide. Different chemical, physical, and biological strategies try to control the expansion of PRM. However, effective solutions to this problem still have to be found. Here, we present a method for the development of an immunological control strategy, based on the identification of mite protein antigens which elicit antibodies with anti-mite activity in the immunized chicken. Hens were immunized with different PRM protein extracts formulated with two different adjuvants, and IgY-antibodies were isolated from the eggs. A PRM in vitro feeding assay which used chicken blood spiked with these IgY-preparations was used to detect antibodies which caused PRM mortality. In vitro feeding of mites with IgY isolated from hens immunized with PRM extract formulated with one of the adjuvants showed a statistically significant increase in the mortality as compared to control mites. After the separation of total PRM extracts in two-dimensional gels, several protein spots were recognized by such IgY preparations. Ten protein spots were subjected to mass spectrometry (MS/MS) for the identification of the corresponding proteins. Complete protein sequences were deduced from genomic and transcriptomic assemblies derived from high throughput sequencing of total PRM DNA and RNA. The results may contribute to the development of an immunological control strategy of D. gallinae.

Immune responses and protective efficacy of recombinant outer membrane protein R (rOmpR)-based vaccine of Aeromonas hydrophila with a modified adjuvant formulation in rohu (Labeo rohita)

Despite the importance and success of developing a candidate vaccine against Aeromonas hydrophila infection in fish, little is known about the molecular mechanisms of the vaccine-induced immunoprotection in Indian major carp, Labeo rohita, primarily due to lack of information on most of the immune related genes of the species. In this study, a novel candidate antigen recombinant outer membrane protein R (rOmpR) of A. hydrophila was evaluated as a vaccine candidate along with a modified adjuvant formulation. Protective efficacy of the rOmpR immunization was assessed in terms of survival against A. hydrophila challenge as well as modulation of immune response in vaccinated fish after 1, 3, 6, 12, 24, 72 h and 10 days post-injection (using immune gene expression analysis) and 10, 28, 56 and 140 days post-injection (serum immune parameter analysis). The generated immune response was compared with a formalin-killed A. hydrophila antigen preparation using mineral oil only and modified adjuvant alone. We report a variable up-regulation of the immune-related genes viz., lysozyme G, complement factor 4, immunoglobulin M, β2-microglobulin, major histocompatibility complex I and II, and interleukin-1β in anterior kidney and spleen tissues at early time points post-immunization in all the groups, when compared to the control fish. The vaccinated fish also showed an increase in serum natural hemolysin titer, lysozyme and myeloperoxidase activities, and antibody titer irrespective of vaccine formulations as compared to control fish on days 10, 28 and 56. However, the increase in the serum parameters was more pronounced on day 140 in rOmpR-modified adjuvant injected group, indicating the modulatory role of this new vaccine formulation. Upon challenge with live A. hydrophila on days 56 and 140 post-immunization, significantly reduced percent mortality was noted in the group immunized with modified adjuvant based rOmpR vaccine formulation. Taken together, our results suggest that rOmpR along with modified adjuvant could potentially be used as a vaccine formulation to handle A. hydrophila infection on a long-term basis.

Inflammatory responses and side effects generated by several adjuvant-containing vaccines in turbot

Several of the adjuvants used in fish vaccines cause adhesions in internal organs when they are injected intraperitoneally. We describe the damage caused by vaccines containing different adjuvants in the turbot Scophthalmus maximus and show that internal adhesions can be greatly reduced by injecting the fish in a specific way. Injection of fish with the needle directed towards the anterior part of the peritoneal cavity induced formation of a single cell-vaccine mass (CVM) that became attached to the parietal peritoneum. However, injection of the fish with the needle pointing in the opposite direction generated many small CVM that became attached to the visceral and parietal peritoneum and in some cases caused internal adhesions. We describe the structural and cellular changes in the adjuvant-induced CVMs. The CVMs mainly comprised neutrophils and macrophages, although most of the former underwent apoptosis, which was particularly evident from day 3 post-injection. The apoptotic cells were phagocytosed by macrophages, which were the dominant cell type from the first days onwards. All of the vaccines induced angiogenesis in the area of contact between the CVM and the mesothelium. Vaccines containing oil-based adjuvants or microspheres induced the formation of granulomas in the CVM; however, no granulomas were observed in the CVM induced by vaccines containing aluminium hydroxide or Matrix-Q(®) as adjuvants. All of the vaccines induced strong migration of cells to the peritoneal cavity. Although some of these cells remained unattached in the peritoneal cavity, most of them formed part of the CVM. We also observed migration of the cells from the peritoneal cavity to lymphoid organs, indicating bidirectional traffic of cells between the inflamed areas and these organs.

Adjuvants and immunostimulants in fish vaccines: current knowledge and future perspectives

Vaccination is the most adequate method to control infectious diseases that threaten the aquaculture industry worldwide. Unfortunately, vaccines are usually not able to confer protection on their own; especially those vaccines based on recombinant antigens or inactivated pathogens. Therefore, the use of adjuvants or immunostimulants is often necessary to increase the vaccine efficacy. Traditional adjuvants such as mineral oils are routinely used in different commercial bacterial vaccines available for fish; however, important side effects may occur with this type of adjuvants. A search for alternative molecules or certain combinations of them as adjuvants is desirable in order to increase animal welfare without reducing protection levels. Especially, combinations that may target specific cell responses and thus a specific pathogen, with no or minor side effects, should be explored. Despite this, the oil adjuvants currently used are quite friendlier with respect to side effects compared with the oil adjuvants previously used. The great lack of fish antiviral vaccines also evidences the importance of identifying optimal combinations of a vaccination strategy with the use of a targeting adjuvant, especially for the promising fish antiviral DNA vaccines. In this review, we summarise previous studies performed with both traditional adjuvants as well as the most promising new generation adjuvants such as ligands for Toll receptors or different cytokines, focussing mostly on their protective efficacies, and also on what is known concerning their effects on the fish immune system when delivered in vivo.

Toxicity and dose determination of quillaja saponin, aluminum hydroxide and squalene in olive flounder (Paralichthys olivaceus)

Adjuvants are substances added to vaccines to enhance the immune response of a given antigen. Most of the adjuvants are toxic at certain doses, and toxicity varies in different species. Moreover, there are no standard dosage limits set for adjuvant use in fish vaccines. We evaluated the acute toxicity, serum enzymes (AST/ALT) indicating hepatic injury and histopathological changes due to intra-peritoneal administration of different concentrations of a panel of adjuvants including quillaja saponin, aluminum hydroxide, squalene emulsion and Freund's incomplete adjuvant (FIA) with a dose ranging study of saponin (500, 160, 50, 16 and 5μgfish(-1)), aluminum hydroxide (5000, 1600, 500, 160 and 50μgfish(-1)), squalene emulsion (20, 10 and 5%), and FIA to determine the acceptable dosage for vaccination in olive flounder (Paralichthys olivaceus) fingerlings measuring 4.66±0.41g, 8.47±0.42cm. Saponin was highly toxic with a LD50 of approximately 105μgfish(-1) (22.4mgkg(-1)) causing severe histological damage and AST level was high at dose above 16μgfish(-1) and ALT, specific for liver damage was high only at 160μgfish(-1) (11U/L) and was safe at 5μgfish(-1). Aluminum hydroxide was toxic at 5000μgfish(-1) and was acceptable at dose below 1600μgfish(-1) with moderate histology and AST/ALT levels similar with control. Squalene emulsion showed increased inflammation at 20% and 10% emulsions and the inflammatory response was mild at a concentration of 5% oil emulsion and AST/ALT levels being similar to control in 10% and 5% emulsions and elevated in 20% on both sampling days. FIA was not lethal, but induced severe inflammation at injection site and around blood vessels. In comparison to FIA, saponin found to be safe at dose of 5μgfish(-1), aluminum hydroxide below 1600μgfish(-1), and squalene at 5% emulsion and could be accepted for vaccination studies. These results provide an insight for the selection of safer dose of adjuvants for intra-peritoneal vaccination of olive flounder.

Scuticociliatosis and its recent prophylactic measures in aquaculture with special reference to South Korea Taxonomy, diversity and diagnosis of scuticociliatosis: Part I Control strategies of scuticociliatosis: Part II

Scuticociliatosis caused by about 20 species belonging to the Phylum Ciliophora has been recognized as an emerging problem inflicting significant economic loss in aquaculture industry in the world. Among these Philasterides dicentrarchi, Miamiensis avidus, and Uronema marinum are the three species responsible for scuticociliatosis in olive flounder farms of South Korea. Some of the parasites living or scavenger ciliates also have become parasites of aquaculture fish. The major clinico-pathological manifestations of scuticociliatosis infected fishes are anemia, weight loss, dark coloration, enteritis, excessive body mucus, yellowish intestinal mucus, loss of scales, hemorrhagic and/or bleached spots on the skin, and dermal necrotic lesions that finally destroy tissues lead to high mortalities. Affected fish exhibit organ-specific pathological changes in the brain, eyes, muscle, gills, liver, kidney, intestine, and stomach that lead to severe mortality. At present, farmers in South Korea manage scuticociliatosis by using therapeutic measures, such as application of antibiotics like oxytetracycline, gentamycine, tetracycline, amoxycililin, and cefazolin and chemicals, such as formalin, hydrogen peroxide, malachite green, and jenoclean at a concentration of 350 +/- 150 ppm. However till date, no systematic scientific study has been conducted under field condition on the efficacy of these management measures. Under laboratory condition the ciliate can be effectively controlled with the antibiotics and chemicals while on the host, but on entering the host no systemic chemotherapeutic treatment has been yet proven effective. Furthermore the indiscriminate uses of harmful chemicals in aquaculture are increasingly becoming a cause of concern. Recently formalin and malachite green, the most widely used chemicals have been banned in food fish production by FDA as not consumer friendly and being carcinogenic respectively. Vaccines and immunostimulants can induce good immune response and protect against scuticociliatosis as it has been proved in the case of freshwater Ich. Now a days a number of probiotics and herbal formulations are in use against freshwater bacterial and fungal diseases, while, little information is available regarding the different prophylactic measures against marine scuticociliatosis. This review attempts to provide information on the various prophylaxic measures practiced against scuticociliatosis with special reference to olive flounder farms in South Korea.

Immune response of turbot, Psetta maxima (L.) (Pisces: Teleostei), to formalin-killed scuticociliates (Ciliophora) and adjuvanted formulations

The increasing frequency of scuticociliatosis in turbot culture has stressed the need of knowledge on the immune responses to these parasites, for further developing of prevention and control strategies. The immune response of turbot to killed parasites, alone (Ag) or in combination with Montanide ISA 763A (MON), was studied in a laboratory-scale experiment. The variations of several innate immune factors and the antibody response were analysed in immunized vs. non-immunized fish at different times after immunization, and also after a challenge with live ciliates. Amongst innate immune factors, serum lysozyme increased progressively in all inoculated groups. Differences in innate immune factors in Ag and Ag-MON fish with respect to controls were mainly evidenced after challenge, especially for serum complement. Serum antibody levels increased in immunized fish after booster and particularly after challenge. In addition, certain protection was obtained for immunized groups compared to controls or to fish receiving MON alone, and the levels of specific antibodies were also the highest in immunized groups. The obtained information could be useful for further design of immunoprophylactic formulations against scuticociliatosis.

Effects of dietary supplementation with clostridium butyricum on the growth performance and humoral immune response in Miichthys miiuy

The effects of dietary supplementation with Clostridium butyricum on growth performance and humoral immune response in Miichthys miiuy were evaluated. One hundred and fifty Miichthys miiuy weighing approximately 200-260 g were divided into five groups and reared in 15 tanks with closed circuiting culture system. The animals were fed 5 diets: basal diet only (control) or supplemented of the basal diet with C. butyricum at doses of 10(3) (CB1), 10(5) (CB2), 10(7) (CB3) or 10(9) (CB4) CFU/g. Compared with the control, the serum phenoloxidase activity was significantly increased by the supplementation (P<0.05), acid phosphatases activity was increased significantly (P<0.05) at the doses of 10(9) CFU/g. Serum lysozyme activity peaked at dose of 10(7) CFU/g and in the skin mucus at dose of 10(9) CFU/g. Immunoglobulin M level in the serum and skin mucus was increased except at dose of 10(3) CFU/g (P<0.05). The growth at the dose of 10(9) CFU/g was higher than that of the control (P<0.05). It is concluded that supplementation of C. butyricum can mediate the humoral immune responses and improve the growth performance in Miichthys miiuy.

Side effects in sea bass (Dicentrarchus labrax L.) due to intraperitoneal vaccination against vibriosis and pasteurellosis

Sea bass (Dicentrarchus labrax L.) were injected intraperitoneally with monovalent (Photobacterium damselae subsp. piscicida or Vibrio anguillarum) and divalent (Ph. damselae subsp. piscicida and V. anguillarum) vaccine formulations, with or without adjuvants (mineral oil, liposome or alginate), to evaluate the short and long-term pathological effects. Eight animals from each group were sampled one, two, four and 11 months after intraperitoneal injection. The acute peritoneal response and the progression to a chronic status were evaluated by analysing peritoneal leucocytes collected during the first days post-injection. To evaluate the chronic response, the late peritoneal leucocyte response was analysed and the peritoneal cavity was examined and the intra-abdominal lesion level scored based on a pre-defined scale. Correlation between leucocyte exudative response, tissue inflammatory response and the development of granuloma were sought. The acute leucocyte response was characterized by an early (24-48 h) mobilization of neutrophils and macrophages, with phagocyte numbers dependent on the formulation, but no significant variations were observed in lymphocytes/small cells and EGCs. Later on, a steady increase occurred in lymphocytes/small cells and EGCs and a high concentration in neutrophils and macrophages was maintained up to 30-60 days in groups i.p. injected with oil adjuvanted formulations with antigen. All the lesions observed were moderate, indicating that in sea bass, the pathological effects due to intraperitoneally injected vaccines are less severe than in other fish species. The divalent oil adjuvanted vaccine induced the most severe side effects, with macroscopic granulomas consistently present up to 11 months.