Relative Percent Survival Research Articles

Efficacy of a formalin-inactivated vaccine against Lactococcus garvieae infection in golden pompano Trachinotus ovatus

Lactococcus garvieae is one of the primary pathogens causing the severe disease to golden pompano (Trachinotus ovatus). Vaccination is the most effective measure of preventing the occurrence and spread of infectious diseases. However, no commercially available vaccine protects T. ovatus against L. garvieae infection. In the present study, the formalin-inactivated L. garvieae vaccines, consisting of bacterin alone (aqueous vaccine) and combined with oil adjuvant Montanide™ ISA 763 A VG (vaccine+763A), were prepared and administered to T. ovatus by intraperitoneal injection. The protective efficacy was evaluated by testing the relative percent survival (RPS), serum enzyme activity, and expression levels of immune-related genes in the tissues of T. ovatus after immunization. The results indicated that the relative percentage survival (RPS) values of aqueous vaccine and vaccine+763A were 80% and 90.8% at 8 weeks post-vaccination. The level of antibody titer, lysozyme activities, superoxide dismutase, and catalase in the two vaccinated fish groups increased significantly compared to that in the control group. Moreover, the expression levels of immune-related genes IgM, TNF-α, IL-8, MHCI-α, MHCII, CD4, CD8α, and IL-1β in all the tested tissues from T. ovatus were significantly enhanced after inoculation with aqueous vaccine and vaccine+763A. These findings demonstrated that the developed vaccine combined with oil adjuvant ISA 763 A VG improved immune responses and provided good protective efficacy against L. garvieae infection in the golden pompano culture.

Recombinant surface display vaccine enhances the immersion immune effect against grass carp reovirus in grass carp (Ctenopharyngodon idella)

Grass carp (Ctenopharyngodon idella) is subject to a hemorrhagic disease caused by grass carp reovirus (GCRV), which can lead to mass mortality in grass carp culture, causing significant economic loss. Vaccination is the most promising strategy for the prevention of infectious diseases. Immersion vaccination is considered the most effective disease prevention method for juvenile fish because it can be implemented on many fish at once and administered without causing stress. However, immune responses by immersion vaccination are markedly less robust due to the skin barrier and insufficient antigen uptake. The display of heterologous proteins on the cell surface has been explored as a delivery system for viral antigens in veterinary and human vaccine studies. To improve the efficacy of the immersion vaccine, the major capsid protein (VP7) of GCRV was co-displayed with Aeromonas hydrophila outer membrane protein a (OmpA) and major adhesion protein (Mah) on the outer membrane surface of nonpathogenic Escherichia coli BL21 using the anchoring motif of ice-nucleation protein (Inp). The immune responses and protection efficiency against GCRV infection via both the injection and immersion routes were evaluated. The results indicated that the activities of anti-oxidant enzymes (ACP, AKP, SOD and T-AOC), as well as the expression of immune-related genes (TNF-α, IL-1β, MHCI and IgM) and specific VP7 antibody levels, were strongly increased in the grass carp from 7 to 21 days post-injection inoculation in a dose dependent manner. The cumulative mortality rates of injection-vaccinated groups were much lower than those of the control group after the GCRV challenge, and the relative percent survival (RPS) was greater than 80 %. Vitally, the surface co-display of vp7-Mah protein conferred marked protection to grass carp against GCRV infection after immersion administration (RPS >50 %); this was consistent with the production of high level of specific serum antibodies, non-specific immune responses, and the expression of immune-related genes. Moreover, the invasion analysis further showed that surface co-display of the vp7-Mah protein indeed significantly improved the invasion of E. coli BL21 (DE3) in vitro. Altogether, this study demonstrated that surface display GCRV core antigen vaccine system accompanied by invasion component from aquatic pathogenic microorganism is an effective prophylactic against GCRV viral diseases via the immersion administration approach.

Transcriptome analysis of turbot (Scophthalmus maximus) kidney responses to inactivated bivalent vaccine against Aeromonas salmonicida and Edwardsiella tarda

Turbot (Scophthalmus maximus) is a commercially important marine flatfish for global aquaculture. With intensive farming, turbot production is limited by several diseases, in which Aeromonas salmonicida and Edwardsiella tarda are two main causative agents. Vaccination is an effective and safe alternative to disease prevention compared to antibiotic treatment. In the previous study, we developed an inactivated bivalent vaccine against A. salmonicida and E. tarda with relative percent survival (RPS) of 77.1 %. To understand the protection mechanism in molecular basis of the inactivated bivalent vaccine against A. salmonicida and E. tarda, we use RNA-seq to analyze the transcriptomic profile of the kidney tissue after immunization. A total of 391,721,176 clean reads were generated in nine libraries by RNA-seq, and 96.35 % of the clean reads were mapped to the reference genome of S. maximus. 1458 (866 upregulated and 592 downregulated) and 2220 (1131 upregulated and 1089 downregulated) differentially expressed genes (DEGs) were obtained at 2 and 4 weeks post-vaccination, respectively. The DEGs were enriched in several important immune-related GO terms, including cytokine activity, immune response, and defense response. In addition, the analysis of several immune-related genes showed upregulation and downregulation, including pattern recognition receptors, complement system, cytokines, chemokines and immune cell surface markers. Eight DEGs (ccr10, calr, casr, mybpha, cd28, thr18, cd20a.3 and c5) were randomly selected for qRT-PCR analysis, which confirmed the validity of the RNA-seq. Our results provide valuable insight into the immune mechanism of inactivated bivalent vaccine against A. salmonicida and E. tarda in Scophthalmus maximus.

Effect of dietary inclusion of mannan oligosaccharides on the efficacy of a novel hydrogen peroxide‐inactivated vaccine against Streptococcus agalactiae in Nile tilapia

AbstractMannan oligosaccharides (MOS) have shown to stimulate immune response in different fish species, but the results may appear contradictory and have not been tested in conjunction with vaccination. We hypothesized that dietary MOS supplementation could enhance efficacy and immune responses after immunization with a novel hydrogen peroxide‐inactivated vaccine. Nile Tilapia, Oreochromis niloticus, fingerlings were distributed into four groups (supplemented or not, vaccinated or not) and were used to determine immune and hematological parameters and somatic indexes. For the bacterial challenge and vaccine efficacy test, fish were assigned to five experimental groups. Twenty‐eight days after the feeding trial and vaccination, the groups were challenged intraperitoneally and monitored for 21 days. The relative percent survival of the groups basal diet‐vaccinated and MOS diet‐vaccinated were 98.1% and 100.0%, respectively. The dietary inclusion of MOS after vaccination for 28 days had no influence on vaccine efficacy, which could be explained because of the high efficacy of the vaccine itself. Therefore, we suggest that the contribution of MOS supplementation to immune responses after vaccination in fish would be greater for vaccines with lower efficacy, or when tested for heterologous challenges or for crossed protection.

Clinical protective effects of polyhexamethylene biguanide hydrochloride (PHMB) against Vibrio parahaemolyticus causing translucent post-larvae disease (VpTPD) in Penaeus vannamei

A new emerging disease called “translucent post-larvae disease” (TPD) in Penaeus vannamei, caused by a novel type of highly lethal Vibro parahaemolyticus (VpTPD), has become an urgent threat to the shrimp farming industry in China. In order to develop an effective disinfectant for the prevention and control of the VpTPD, the clinical protective effects of polyhexamethylene biguanide hydrochloride (PHMB) against VpTPD in Penaeus vannamei were investigated by carrying out an acute toxicity test of PHMB on post-larvae of P. vannamei and its effect of treatment test on VpTPD infection. The results showed that the median lethal concentration of disinfectant (LC50) values of PHMB to post-larvae of P. vannamei after treatment for 24 h, 48 h, 72 h, 96 h were 16.13 mg/L (14.18–18.57), 10.77 mg/L (9.93–11.72), 9.68 mg/L (8.53–11.64), 9.14 mg/L (7.70–10.99), respectively. In addition, a clinical trial showed that 1 mg/L PHMB showed a strong protective effect on the post-larvae of shrimp challenged with 101-104 CFU/ml of VpTPD. The relative percentage survival (RPS) of 1 mg/L PHMB on post-larvae of P. vannamei challenged with VpTPD at 101, 102, 103 and 104 CFU/ml were 63.65 %±6.81, 62.96 %±5.56, 60.00 %±3.75 and 66.67 %±3.75 at 96 hours post infection. The results highlight the clinical protective effects of the PHMB and therefor PHMB can be used as a preventive measure to control early TPD infection in shrimp culture. This study also provides valuable information for the prevention of other bacterial diseases in shrimp culture.

Formulation of chitosan microsphere-based oral vaccine against the scuticociliate parasite Miamiensis avidus: Evaluation of its protective immune potency in olive flounder (Paralichthys olivaceus)

Miamiensis avidus is a parasitic pathogen that causes scuticociliatosis, a severe and often lethal marine infection that affects marine fishes worldwide, including olive flounder (Paralichthys olivaceus) in Korea. This parasite infects all size groups of flounder year-round, causing recurring mortalities and huge economic losses to the Korean flounder industry each year. However, few efforts have been made to implement effective remedial measures to control this parasite. Therefore, our study sought to develop a chitosan microsphere (MS)-encapsulated inactivated vaccine (IMa + chitosan) for oral delivery (adsorbed in feed) to flounder fingerlings and assess its protective efficacy at different modalities via three in vivo experimental trials. Immunisation trial-1 was conducted to determine the effective concentration of chitosan. Our findings indicated that an IMa + chitosan 0.05 % vaccine formulation was safe and effective in providing moderate protection [46.67%–53.3 % relative percent survival (RPS)] against M. avidus intraperitoneal (IP) injection challenge at two weeks post-vaccination (wpv) compared to the IMa + chitosan 0.01 % and IMa + chitosan 0.005 % vaccines (0%–13.3 % RPS) irrespective of the antigen doses. In trial-2, the IMa + chitosan 0.05 % vaccine elicited similar protective immunity (30.8%–57.1 % RPS) in olive flounder against M. avidus at varying antigen doses (high: 2.38 × 106 cells/fish; low: 1.5 × 105 cells/fish), immunisation periods (2 and 5 wpv), and challenge modes (IP injection and immersion). Furthermore, experimental trial-3 validated the use of chitosan MS as an IMa antigen carrier to improve survivability (41.7 % RPS) in the host by significantly (p < 0.05) upregulating specific anti-M. avidus antibody titres in the fish sera and mucus of the group immunised with IMa-containing chitosan MS. In contrast, non-specific immunomodulatory effects (16.7 % RPS and enhanced mucosal antibody titres) were observed in the group treated with chitosan MS without IMa. Therefore, our findings suggested that oral administration of chitosan MS (0.05 %)-encapsulated IMa vaccine is a promising immunisation strategy against M. avidus that can protect the IMa antigen from digestive degradation, facilitates its targeted delivery to the host immune organs, and helps in orchestrating protective immune induction in olive flounder, thus controlling parasite infection.

Efficient showering vaccination with a live attenuated vaccine against herpesviral hematopoietic necrosis in goldfish

Herpesviral hematopoietic necrosis caused by cyprinid herpesvirus 2 (CyHV-2) frequently affects farmed goldfish Carassius auratus and gibel carp C. auratus gibelio, leading to significant economic damage. In our previous study, a live attenuated vaccine, called the P7-P8 vaccine strain, was developed by propagating virulent CyHV-2 in two non-natural host cell lines. The vaccine demonstrated high protective efficacy in goldfish with no signs of virulence reversion. Methods that reduce the costs of the procedure, including labor costs, are warranted for the practical application of this vaccine in goldfish aquaculture. The aim of this study was to explore alternative vaccination protocols for the P7-P8 strain in goldfish. First, we tested the previous standard administration protocol which is the bath vaccination with 1: 1000 diluted vaccine cultures for 2 h. In the simple first step to reduce vaccine virus culture, we examined the bathing protocol with more-diluted virus culture (ranging from 1: 1000 to 1: 81,000). The relative percentage survival (RPS) after the virulent virus immersion challenge for 2 h at 21 days post-vaccination was remarkably decreased in a dose-dependent manner; a dilution of 1: 3000 resulted in a 19% reduction from that used in the standard bathing protocol. Therefore, alternative methods (dipping and showering vaccination protocols) were tested using a 1: 100 dilution vaccine culture (10-fold more concentrated than the standard protocol) with short exposure times. Dipping vaccination for 10 s, 1 min, 2 min, and 5 min showed sufficient RPS of 82.4%–100%. The 10 s process was repeated six times using the same vaccine solution, resulting in an RPS >89%. In the showering vaccination protocol, the vaccine solution (1: 100 dilution; 1 mL, 3 mL, or 5 mL) was showered onto 20 goldfish on a net and held for 10 s, resulting in an RPS of >89%. We selected the showering vaccination as the suitable vaccination protocol. The effectiveness of this vaccination protocol was tested using the virus challenge by employing the cohabitation method with infected fish. The results showed high protective efficacy with an RPS of 65%–100%. This study demonstrated that the showering vaccination protocol, which uses small amounts of vaccine culture and produces less waste vaccine solution with short labor time, may be considered as a suitable alternative to the standard bath method in goldfish aquaculture.

Oral self-microemulsifying drug delivery system for honokiol's stress responses attenuation and anti-Cryptocaryon irritans efficacy enhancement in Trachinotus ovatus

In this study, an oral self-micro-emulsifying drug delivery system of honokiol (HN-SMEDDS) was developed to overcome honokiol's disadvantages, such as poor aqueous solubility and induced stress responses. The safeties of HN-SMEDDS and honokiol dimethyl sulfoxide aqueous solution (HN-DMSO) were evaluated by comparing their hemolytic activity and acute toxicity in pompano (Trachinotus ovatus). The one-h-ten-percent hemolytic concentration (EC10) of HN-SMEDDS on pompano erythrocytes was 1.206 mg/mL, 33.5 times that of HN-DMSO. And the minimum lethal doses (MLD) for HN-SMEDDS and HN-DMSO in pompano were 1000 mg/kg and 500 mg/kg, respectively. The 14-d relative percent survival (RPS) was calculated after orally administering substance HN-SMEDDS at various doses in pompano cryptocaryoniasis, revealing an optimal dose of 400 mg/kg. To assess efficacy, a comparison was carried out between the oral administration of HN-SMEDDS and HN-DMSO in treating pompano cryptocaryoniasis. This comparison was based on the 14-d RPS and the quantification of C. irritans trophonts in the right second gill (NCTG). In the challenged pompanos treated with HN-SMEDDS and HN-DMSO, the 14-d RPS and 7-d NCTG reached 68.89 ± 3.14% and 6.3 ± 2.1 individuals, and 53.33 ± 0.00% and 30.7 ± 2.1 individuals, respectively. Furthermore, stress-related markers, encompassing mRNA levels of cyp1a, hsp70, gst, and sod in the liver, spleen, and kidney, along with activities of ACP, CAT, SOD, GSH, and T-AOC in these organs and serum, were compared between the pompanos administered with HN-SMEDDS and HN-DMSO. The impact of HN-SMEDDS on the mRNA levels of cyp1a in the liver and kidney, hsp70 in all the analyzed tissues, gst in the liver and spleen, sod in the spleen, as well as the activities of ACP and CAT in liver, spleen, and serum, GSH content in spleen and kidney, SOD in the liver, kidney, and serum, and the T-AOC in liver, spleen, kidney, and serum, were significantly smaller than those of HN-DMSO. Compared to HN-DMSO, HN-SMEDDS could markedly reduce the stress responses of fish and enhance the efficacy of honokiol.

Effect of Astragalus membranaceus on Transcriptome and Survival of Hybrid Yellow Catfish (Pseudobagrus vachellii ♂ × Tachysurus fulvidraco ♀) in Response to Aeromonas hydrophila Challenge

Intensive culturing of hybrid yellow catfish (Pseudobagrus vachellii ♂ × Tachysurus fulvidraco ♀) has increased their mortality. Astragalus membranaceus has been used as an immune stimulant and antioxidant in fish for several years. A. membranaceus was decocted and mixed with the diet. After feeding for 28 d, the hybrid yellow catfish were challenged with Aeromonas hydrophila. To better understand the function of A. membranaceus in the defense of hybrid yellow catfish against A. hydrophila, we analyzed the spleen transcriptome data and relative percentage survival (RPS). There were 396 differentially expressed genes (DEGs) between the A. membranaceus and control groups at 24 h after A. hydrophila stimulation, including 263 upregulated and 133 downregulated DEGs. A significant enrichment of DEGs was found in the A. membranaceus group when the GO enrichment terms in the spleen were analyzed. The qRTPCRresults for the five upregulated and two downregulated DEGs from the spleen, intestine, and liver were consistent with the transcriptome data. The relative percentage survival of A. membranaceus was 85.71% after the fish were challenged with A. hydrophila.

Oil Based Inactivated Vaccine Formulation for Furunculosis (A. salmonicida) and Protective Immune Response of Rainbow Trout and Brown Trout

The development and growth of the fisheries and aquaculture industries are significantly hampered by illnesses. It is critical to combat pathogenic illnesses, especially bacterial ones. Furunculosis in salmon is mostly brought on by Aeromonas salmonicida in rainbow and brown trout. To control this pathogen, vaccines have been identified as a significant tool. In the present study, we have formulated an inactivated vaccine with oil as an adjuvant and estimated its efficacy. The lethal dose of ArS-Pak-19, was calculated and injected intraperitoneally to the fishes. To analyze the infection, samples of kidney, liver, spleen, and blood were collected at specific times. To estimate the immunogenicity of the vaccine, an experiment was designed. One hundred sixty fishes were distributed into 8 tanks including, six experimental groups and two control groups with its replicates, vaccines injected intraperitoneally 1.6 × 107, 1.6 × 108, and 1.6 × 109 and blood samples were taken fortnightly for 56 days to calculate the antibodies titers. After immunization these groups were challenged with Aeromonas salmonicida (ArS-Pak-19) intraperitoneally. At 7th day of post infection, it appeared in the liver, spleen, and kidney. The relative percentage of survival was estimated with control groups at 30 days after challenge. The relative percentage of survival was 80%. The IgM titers were higher at 24 days of post immunization. We also analyzed that antibodies non-specifically bound with the A-layer of Aeromonas salmonicida. The findings of this study offer evidence that vaccinations boost fishes immunity and serve as a roadmap to further vaccination initiatives.

Efficacy of the Whole Cell Vaccine Streptococcus agalactiae with Vector Artemia sp. for Streptococcosis Prevention in Nila Fish (Oreochromis niloticus)

This study aims to examine the efficacy of the oral whole-cell vaccine of S. agalactiae with Artemia sp as a vaccine vector for prevention against Streptococcosis in tilapia fish. The fish seeds used in the study were 2-3 cm in size which did not carry S. agalactiae bacteria and were reared in jars with a volume of 3 liters as many as ten birds/jar. Giving the vaccine to fish orally by first soaking the vaccine in Artemia sp. The soaking times for the vaccine were 15, 30, 60, 90, 120 and 150 minutes. Parameters observed were relative percent survival (RPS), antibody titer value, total leukocytes, phagocytic index, and leukocyte differential. The results showed that the treatment between vaccines had no significant effect, while the treatment with the control vaccine had a significant effect (P&lt;0.05). The highest RPS value was obtained in the vaccine soaking treatment in Artemia sp. for 30 minutes and 120 minutes, with a value of 93.33%. Furthermore, the RPS was 86.67% at 15 and 150 minutes of soaking and 80% RPS at 30 minutes of soaking. This shows that the level of vaccine protection against streptococcosis in tilapia fish is very high.

Injection administration of mangosteen, Garcinia mangostana, husk extract enhances physiological and immune-neuroendocrinological regulation of Macrobrachiumrosenbergii

The study aimed to investigate the effects of injecting mangosteen husk hot-water extracts (MHE) on immune and physiological factors in Macrobrachium rosenbergii. Different doses of MHE (10, 20, and 40 μg prawn−1) were injected into the prawns, and various immune and physiological parameters were evaluated. The results revealed that higher doses of MHE (20 and 40 μg prawn−1) led to significant increases in immune parameters, improved phagocytic activity, and clearance efficiency. However, certain parameters, such as phenoloxidase activity per granulocyte, plasma glucose, and lactate levels were decreased after injection. Moreover, prawns injected with MHE and subjected to hypothermal stress exhibited changes in haemolymph dopamine and norepinephrine. Prawns injected with MHE for 7 days showed increased survival rates when challenged with Lactococcus garvieae. The relative survival percentages were 11.8%, 46.6%, and 47.1% for MHE doses of 10, 20, and 40 μg prawn−1 injection, respectively, indicating enhanced resistance to the pathogen. In conclusion, injecting MHE can act as an immunostimulant and physiological and neuroendocrine regulator for prawns, enhancing their resistance to L. garvieae.

Pathogenicity and inactivated vaccine treatment of Aeromonas veronii JW-4 on crucian carp

Aeromonas veronii is a common bacterium found in a variety of aquatic environments, capable of causing a diverse array of diseases in both aquatic animals and humans. Therefore, evaluating the pathogenicity of A. veronii and implementing measures to control its spread are essential. In this study, a strain JW-4, identified as A. veronii, was isolated from diseased Scaphesthes macrolepis, a grade Ⅱ protected animal in China. To investigate the pathogenicity of the strain, fish were fed with serial levels JW-4 supplemented diet or basal diet (control group 1, CG1) for 28 days (d). Results showed that JW-4 stimulated an immune response, evidenced by an increase in immune-related enzyme activities (GOT and GPT) of serum and liver and an upregulation of genes expression levels (TNF-α and IFN-γ) of liver and spleen, and these effects gradually decreased over time. Histopathological examination revealed that JW-4 could alter the tissue structure of immune organs, such as liver and kidney. These changes were accompanied by vacuolar degeneration, nuclear dissolution, and an increased lymphocyte count. To assess protective effects of a vaccine against this strain, fish were injected with an inactivated vaccine (immunization group, IG) or 0.85% sterile saline (control group 2, CG2) for 28-day observation period, then challenged with JW-4 on the 28th day. The inactivated vaccine enhanced total and specific IgM to A. veronii levels of the fish, resulting in a relative percentage survival of 75% in IG. These findings provide a foundation for identifying pathogenic bacteria and developing more effective prophylactic strategies in aquaculture.

Vaccination with bacterial ghosts of Streptococcus iniae and Lactococcus garvieae originated from outbreak of marine fish streptococcosis, induce potential protection against the disease in Nile tilapia, Oreochromis niloticus (Linnaeus, 1758)

Streptococcosis is an important bacterial disease affects fresh, brackish and marine fish. The disease caused annual severe economic losses in Egyptian Mari-culture. S. iniae and L. garvieae usually the main causative agents isolated. The presented study conducted to prepare bacterial ghost vaccine (BGV) candidates from isolated strains of marine streptococcosis outbreaks using NaOH chemical approach. Selected strains confirmed as pathogenic for Nile tilapia, therefore the fish selected as an experimental model. In such respect, the re-isolated S. iniae and L. garvieae were used for ghost preparations, BGVs evaluation and fish challenges. Apart of four, three fish groups namely, A, B, C designated for BGVs evaluations, while the fourth one (D) designated as control. Vaccination experiments performed via intra-peritoneal injection with 0.1 mL (1.5 × 108 CFU/mL/fish) of their corresponding BGVs twice with 2 weeks’ interval; however, control fish received 0.1 mL of fish saline instead. Blood, serum, and tissue samples collected from all groups at 2 and 4 weeks post immunization (PI) for estimation of hematological, innate, and specific immune parameters. At the end, all remained fish challenged with appropriated pathogen (s) and the relative percentage of survival (RPS) calculated. Three BGVs generated namely, SiG, in addition to, novel contributions of LgG and SiLgG. Ghosts were corresponding to S. iniae, L. garvieae and their both ghost mixtures, respectively. Fish groups immunized with prepared BGVs revealed variable significant increases in PCV, GLB, PP, SOD, CAT, C5, IL-β1, LZM, specific antibody titers and CD4 expression 2 and 4 weeks PI. MDA decreased in all vaccinated groups that was significantly with group C. Expression of MHC-II showed elevations 2 weeks PI, however, it significantly decreased at 4 weeks. The RPS recorded 90, 88.89 and 95.46% in immunized groups A, B and C, respectively. At all levels tested, obtained results proposed SiG, LgG and SiLgG as innovative vaccine candidates, which can protect cultured fish from being attacked by S. iniae, and/or L. garvieae.

Pengaruh Nanovaksin Berbasis Nanopartikel Hybrid Chitosan Terhadap Sel Darah Ikan Kerapu Cantang Yang Diinfeksi VNN

Cantang grouper (Epinephelus sp.) is a fish with a high economic value and has been widely cultivated. VNN disase, caused by Betanodavirus infection, can lead to mass mortality of cantang grouper. Precautions considered effective in preventing Viral nervous necrosis (VNN) disease include vaccination. This study aimed to determine the effect of administering recombinant Chlorella vulgaris protein nanovaccine based on chitosan hybrid nanoparticles in increasing the immune response of cantang grouper infected with VNN. The study consisted of five treatments: K+ (cantang grouper infected with VNN), K- (healthy cantang grouper), T1 (healthy cantang grouper given 33 µl of nanovaccine and then challenged with VNN), T2 (healthy cantang grouper given 66 µl of nanovaccine and then tested with a VNN challenge), and T3 (healthy cantang grouper given 112 µl of nanovaccine and then tested with a VNN challenge). The parameters observed were haematology, nanovaccine Relative percent survival (RPS), and Survival rate (SR) levels. The study results showed that administering the nanovaccine increased the immune response of the fish, as indicated by an increase in haematology response, RPS, and SR in cantang grouper compared to the treatment without nanovaccine administration. The best dose of nanovaccine in this study is 33 µl.&#x0D; &#x0D; Keywords: fish disease, nanovaccines, virus, C. vulgaris, grouper

Efficacy of bivalent vaccine against Aeromonas salmonicida and Edwardsiella tarda infections in turbot.

In recent years, more than one pathogenic organism has usually been isolated from diseased turbot Scophthalmus maximus, creating a pressing need for the development of combination vaccines to prevent fish diseases brought on simultaneously by various infections. In this study, the inactivated bivalent vaccine of Aeromonas salmonicida and Edwardsiella tarda was prepared by the formalin inactivation method. After challenge with A. salmonicida and E. tarda at 4 weeks post-vaccination in turbot, the relative percentage survival (RPS) of the inactivated bivalent vaccine was 77.1%. In addition, we assessed the effects of the inactivated bivalent vaccine and evaluated the immunological processes after immunization in a turbot model. Serum antibody titer and lysozyme activity of the vaccinated group were both upregulated and higher than that in control group after vaccination. The expression levels of genes (TLR2, IL-1β, CD4, MHCI, MHCⅡ) that related to antigen recognition, processing and presentation were also studied in the liver, spleen and kidney tissues of vaccinated turbot. All the detected genes in the vaccinated group had a significant upward trend, and most of them reached the maximum value at 3-4 weeks, which had significant differences from the control group, suggesting that antigen recognition, processing and presentation pathway was activated by the inactivated bivalent vaccine. Our study provides a basis for further application of the killed bivalent vaccine against A. salmonicida and E. tarda in turbot, making it good potential that can be applied in aquaculture.

Survival and Immune Responses of F1 Transgenic Tiger Shrimp Penaeus monodon Against White Spot Syndrome Virus (WSSV)

Transgenic technology has been applied to tiger shrimp Peneus monodon to produce a resistant strain to white spot syndrome virus (WSSV) by antiviral gene overexpression. The founders (F0) transgenic tiger shrimp have been successfully bred to produce the first generation (F1). The present study aimed to evaluate the survival and immune responses of F1 transgenic tiger shrimp against WSSV. The F1 transgenic and non-transgenic shrimp (control) with an average weight of 7.93±1.49 g were collected from the controlled brackish water ponds and stocked in a 20 L fiberglass tank with a density of 5 shrimp/tank. The transgenic shrimps were confirmed by a PCR assay. The shrimp were intramuscularly injected with WSSV to evaluate the performance between transgenic and non-transgenic. The survival (SR) was observed daily after the challenge test. Measurement of immune responses, namely total haemocyte count (THC), differential haemocyte count (DHC), prophenoloxidase (proPO) activity, and RNA content in haemolymph was conducted on before challenge, and on the 1st, 3rd, and 5th days after challenge. The survival and immune responses were statistically analysed by the t-student test. The results showed that the SR of transgenic (52.0%), with a relative percentage survival of 47.82%, was greater (P&lt;0.05) than the control shrimp (8.0%). The THC, proPO, and RNA content of the transgenic shrimp was higher (P&lt;0.05) than the non-transgenic shrimp. The results suggested that the transgenic tiger shrimp, due to antiviral gene overexpression, increased the resistance against WSSV.

A subunit vaccine encoding glycoprotein holds potential to protect snakehead (Channa argus) from snakehead vesiculovirus infection

Snakehead vesiculovirus (SHVV) is one of the most harmful viral diseases to the snakehead farming industry. Subunit vaccines with highly protective effects strongly depend on the type of vaccine antigen. In order to screen the potential antigen proteins with efficient immunogenicity and reactogenicity, the glycoprotein (G), matrix protein (M), nucleoprotein (N) and phosphoprotein (P) of SHVV were molecular cloned, sequences analyzed and prokaryotic expressed in this study, then four recombinant proteins were served as subunit vaccines to immunize snakehead by intraperitoneal injection to evaluate the immune effects based on the indexes including the serum antibody level, nonspecific enzyme activity, immune-related gene expression and relative percent survivals (RPS). The results showed that compared with control group, the serum antibody levels and T-AOC activities were significantly higher in all four subunit vaccine groups, the serum ACP and AKP activities in four subunit vaccine groups were higher with different degree, and the detected immune-related genes expression levels were remarkably higher in four subunit vaccine groups except IL-8 gene in spleen of rP group. Among four subunit vaccines, rG protein displayed better immune effect than other three proteins. Besides, the RPS of rG group was highest with 83.3%, followed by rM (66.7%), rN (50.0%) and rP (8.3%), respectively. The above results indicated that glycoprotein was a better candidate protective antigen of SHVV and held potential to protect Snakehead from SHVV infection in the type of subunit vaccine.

Effect of cinnamon (Cinnamomum verum) extracts on the growth and protection ability of tilapia (Oreochromis spp.) against Streptococcus agalactiae

This study was conducted to investigate the effect of cinnamon (Cinnamomum verum) extract mixed to feed on growth parametersand the ability to protect tilapia against Streptococcus agalactiae isolated from infected tilapia (Oreochromis spp.) in Cu Chi district, Ho Chi Minh city. Cinnamon extract was mixed to feed with doses of 10, 20, and 40 g/kg feed. Fish were intraperitoneally injected with 0.1 ml of 1.8x104 CFU/ml of S. agalactiae. The negative control was injected with 0.1 ml of physiological saline. The results showed that the cinnamon extract (C. verum) mixed at the three above levels was shown to be safe for the growth and survival rate of tilapia. Moreover, cinnamon extracts well mixed at 20 g/kg feed proved the highest protection (with the relative percent survival (RPS) value being 51.4%). The cinnamon extract can be considered a potential herbal extract for the prevention of disease caused by S. agalactiae in tilapia.

Dietary supplementation of Nile tilapia (Oreochromis niloticus) diets with bay laurel (Laurus nobilis): alleviation of oxidative stress and amelioration of immune response, serum biochemistry, and resistance against Aeromonas hydrophila.

Herbal plants can enhance immunity and alleviate oxidative stress in fish. Therefore, the present work was performed to evaluate the effects of bay laurel (Laurus nobilis) on growth, immunity, antioxidant activities, disease resistance, and hematology in Nile tilapia (Oreochromis niloticus). A total of 225 Nile tilapia fingerlings (average weight 15.36 ± 0.04g) were divided into five treatment groups and fed with bay laurel at 0, 10, 15, 20, and 25g/kg diet for 90days. A completely randomized design with three replications was applied. The significantly (p < 0.05) improved weight growth (WG), food conversion ratio (FCR), average daily growth (ADG), protein efficiency ratio (PER), and survival rate were observed in fish fed with bay laurel-supplemented diet at the rate of 15g/kg. Significantly improved red blood cells (RBCs) count, white blood cells (WBCs), hemoglobin (Hb), and significantly declined alanine aminotransaminase (ALT) and aspartate transaminase (AST) were found in the same diet-fed group. The immune response parameters such as nitro blue tetrazolium (NBT), lysozyme activity, phagocytic activity, total serum protein, serum albumin, serum globulin, and albumin-globulin ratio were found significantly improved at 15g/kg bay laurel supplemented diet. The improved antioxidant response (catalase, glutathione peroxidase, malondialdehyde, total antioxidant activity) was also observed in the same diet-fed group. Relative percent survival after the fish challenged against Aeromonas hydrophila was significantly (p < 0.05) different. Overall, bay laurel supplementation at a 15g/kg diet improved the nutritional physiology and immunity and, therefore, could be a potential growth-promoting feed additive for aquaculture development.