Rapid Apta-Chromogenic Detection Method for Nitrofuran Metabolite Determination.

Nitrofuran (NF) contamination in food products is a global problem resulting in the banned utilization and importation of nitrofuran contaminated products. A novel chromogenic detection method using a specific DNA aptamer with high affinity and specificity to nitrofurans was developed. Single-stranded DNA aptamers specific to nitrofuran metabolites, including 3-amino-2-oxazolidinone (AOZ), 3-amino-5-methylmorpholino-2-oxazolidinone (AMOZ), and 1-aminohydantoin (AHD), were isolated using magnetic bead-SELEX. The colorimetric detection of nitrofurans using gold nanoparticles (AuNPs) exhibited an AOZ detection range of 0.01-0.06 ppb with a limit of detection (LOD) of 0.03 ppb. At the same time, this system could detect AMOZ and AHD at a range of 0.06 ppb and 10 ppb, respectively. The fast nitrofuran extraction method was optimized for food, such as fish tissues and honey, adjusted to be completed within 3-6 h. This novel apta-chromogenic detection method could detect NF metabolites with a sensitivity below the minimum required performance limit (MPRL). This analysis will be valuable for screening, with a shortened time of detection for aquaculture products such as shrimp and fish muscle tissues.

Refolded recombinant major capsid protein (MCP) from Infectious Spleen and Kidney Necrosis Virus (ISKNV) effectively stimulates serum specific antibody and immune related genes response in Nile tilapia (Oreochromis niloticus).

Infectious spleen and kidney necrosis virus (ISKNV) is a causative agent of high mortality in fish resulting in significant economic loss to the fish industry in many countries. The major capsid protein (MCP) (ORF006) is an important structural component that mediates virus entry into the host cell, therefore it is a good candidate antigen of ISKNV for subunit vaccine development. In this study, MCP of ISKNV was successfully produced in Escherichia coli strain Ril and was purified as the soluble form by refolding recombinant MCP using urea in combination with dialysis process. The refolded recombinant MCP protein had ability of oligomerization to become trimer like native MCP protein. Fish immunized with refolded recombinant MCP showed significantly higher serum antibody titer than fish immunized with insoluble form of the protein (p < 0.05) at 21, 28- and 35-day post-immunization (dpi). Analysis of immune-related genes response in spleen and kidney of fish immunized with refolded recombinant MCP suggested that MHC-I, MHC-II, IL-1ß and IL-4 genes were also significantly expressed relative to the group immunized with insoluble protein (p < 0.05) at 14, 21, 28- and 35-day post immunization. The highest serum antibody and immune related genes response were found at 28 day post immunization. Therefore, refolded recombinant MCP should be better than previously reported insoluble form as the candidate subunit vaccine to prevent infection of Nile tilapia from ISKNV.

Biosensors for the detection of organophosphate exposure by a new diethyl thiophosphate-specific aptamer.

OBJECTIVE: An aptamer specifically binding to diethyl thiophosphate (DETP) was constructed and incorporated in an optical sensor and electrochemical techniques to enable the specific measurement of DETP as a metabolite and a biomarker of organophosphate exposure. RESULTS: A DETP-bound aptamer was selected from the library using capillary electrophoresis-systematic evolution of ligands by exponential enrichment (CE-SELEX). A colorimetric method revealed that the aptamer had the highest affinity for DETP, with a mean Kd value (± SD) of 0.103 ± 0.014 µM. The docking results and changes in resistance showed that the selectivity of the aptamer for DETP was higher than that for the similar structures of dithiophosphate (DEDTP) and diethyl phosphate (DEP). The altered amplitude of cyclic voltammetry showed a linear range of DETP detection covering 0.0001-10 µg/ml with a limit of detection of 0.007 µg/ml. The recovery value of a real sample of pH 7 was 97.2%. CONCLUSIONS: The current method showed great promise in using the DETP-specific aptamer to detect the exposure history to organophosphates by measuring their metabolites, although degradation of organophosphate parent compounds might occur.

Development of fish vaccine in Southeast Asia: A challenge for the sustainability of SE Asia aquaculture.

Southeast (SE) Asia plays an important role in global food security as this region has been regarded as one of the major producers of aquaculture product and, to date, freshwater fish accounted for one-third of the total aquaculture in SE Asia. The intensification of freshwater farming corresponding to increase of consumer demands has inevitably led to the emergence and re-emergence of diseases causing tremendous economic loss in the region. Nile tilapia (Oreochromis niloticus) and striped catfish (Pangasianodon hypophthalmus), the major freshwater fish species of SE Asia, have been reported susceptible to several bacterial pathogens, e.g. Streptococcus agalactiae, Edwardsiella ictalurid and Flavobacterium columnare. Since only a limited number of vaccines being registered and marketed, these pathogenic organisms still represent a severe threat to aquaculture industry in SE Asia. However, there is profound advancement in the understanding of disease epidemiology, pathogenic mechanisms, teleost mucosal immunity and vaccine delivery system over the last few years. This review aimed to summarize those recent findings which hopefully can provide novel insight into the future development of suitable vaccine and vaccination regime against bacterial infection in SE Asia region.

Comparative genomics inferred two distinct populations of piscine pathogenic Streptococcus agalactiae, serotype Ia ST7 and serotype III ST283, in Thailand and Vietnam.

The genomes of Streptococcus agalactiae (group B streptococcus; GBS) collected from diseased fish in Thailand and Vietnam over a nine-year period (2008-2016) were sequenced and compared (n = 21). Based on capsular serotype and multilocus sequence typing (MLST), GBS isolates are divided into 2 groups comprised of i) serotype Ia; sequence type (ST)7 and ii) serotype III; ST283. Population structure inferred by core genome (cg)MLST and Bayesian clustering analysis also strongly indicated distribution of two GBS populations in both Thailand and Vietnam. Deep phylogenetic analysis implied by CRISPR array's spacer diversity was able to cluster GBS isolates according to their temporal and geographic origins, though ST7 has varying CRISPR1-spacer profiles when compared to ST283 strains. Based on overall genotypic features, Thai ST283 strains were closely related to the Singaporean ST283 strain causing foodborne illness in humans in 2015, thus, signifying zoonotic potential of this GBS population in the country.

Feeding-regimen of ß-glucan to enhance innate immunity and disease resistance of Nile tilapia, Oreochromis niloticus Linn., against Aeromonas hydrophila and Flavobacterium columnare.

ß-glucan is one of the most potent immunostimulants enhancing innate immune activity, disease resistance and growth performance of many aquatic organisms. Nevertheless, there are few studies on feeding regimens of ß-glucan that correlate to immune response and disease resistance and are important considerations for practical ß-glucan utilization. Thus, the effect of ß-glucan and feeding duration on innate immunity and disease resistance was investigated to establish an optimal feeding regimen of ß-glucan for Nile tilapia (Oreochromis niloticus Linn.). A variety of ß-glucan feeding regimens were evaluated, including: i) feeding for 2 weeks, ii) feeding for 4 weeks, and iii) feeding every-other-week, with the objective of establishing the optimal feeding regimen that enhanced innate immunity and disease resistance. Innate immunity parameters were determined every week for eight weeks. Alternative complement activity of all ß-glucan groups was significantly (P < 0.05) increased at the end of the first week, and then fluctuated but was not significantly (P > 0.05) different to the control until the end of the trial. Increased lysozyme activity was only detected at the end of the second week in all ß-glucan-treated groups, and then decreased to the control level during most of the sampling periods. Phagocytosis percentage was increased and prolonged by ß-glucan feeding, while the phagocytic index was not. Apart from innate immunity, ß-glucan-fed fish demonstrated enhanced disease resistance against Aeromonas hydrophila and Flavobacterium columnare challenge at only the end of the fourth week of the trial. The growth performance of ß-glucan-fed fish was not significantly (P > 0.05) different among the experimental groups and control. Taken together, the result indicated that all ß-glucan-feeding regimens resulted in quite similar outcomes with respect to innate immunity stimulation, disease resistance and growth performance. This novel result suggests that an every-other-week regimen is the optimal choice for Nile tilapia cultivation as an economic cost saving benefit. This is the first study to determine the optimal feeding-regimen of ß-glucan to enhance innate immunity and increase resistance to infection by pathogenic bacteria in Nile tilapia.

Effects of the dietary supplementation of mixed probiotic spores of Bacillus amyloliquefaciens 54A, and Bacillus pumilus 47B on growth, innate immunity and stress responses of striped catfish (Pangasianodon hypophthalmus).

The study used the mixed probiotics of Bacillus amyloliquefaciens 54A and B. pumilus 47B isolated from striped catfish (Pangasianodon hypophthalmus) intestine aiming to stimulate growth performance, innate immunity, stress tolerance of striped catfish. The average weight gain (AWG), specific growth rate (SGR), and feed conversion ratio (FCR) were analyzed after fish were fed the mixture of probiotics (B. amyloliquefaciens 54A and B. pumilus 47B) at concentrations of 1 × 108, 3 × 108, and 5 × 108 CFU g-1 feed for 90 days. Immunity parameters, survival rate of fish challenged with Edwardsiella ictaluri and ammonia tolerance were also investigated. The amounts of B. amyloliquefaciens and B. pumilus were counted and identified by specific primer pairs of Ba1-F/Ba1-R, and 16-F/Bpu-R to confirm the presence of probiotics in fish intestine. The AWG (476.6 ± 7.81 g fish-1) of fish fed probiotics at 5 × 108 CFU g-1 was significant higher than the control (390 ± 25.7 g fish-1) after 90 days of feeding, but there was no significant (P > 0.05) effect of probiotics on FCR and SGR. Fish fed diet containing probiotics at 5 × 108 CFU g-1 also expressed resistance to E. ictaluri infection and higher immune parameters such as phagocytic activity, respiratory bursts, and lysozyme activity than the control. Stress response with ammonia showed significantly lower mortality rate (25%, 20% and 27%) of fish fed probiotics at all three levels of 1, 3 and 5 × 108 CFU g-1 than the fish fed control diet (75%). The study also demonstrated that the probiotics survived in the intestine of striped catfish after 90 days of feeding. Therefore, the dietary supplementation of a mixture of B. amyloliquefaciens and B. pumilus at 5 × 108 CFU g-1 can be used to improve the health and growth rate of striped catfish.

Molecular cloning and characterization of Siamese crocodile (Crocodylus siamensis) copper, zinc superoxide dismutase (CSI-Cu,Zn-SOD) gene.

Superoxide dismutase (SOD, EC 1.15.1.1) is an antioxidant enzyme found in all living cells. It regulates oxidative stress by breaking down superoxide radicals to oxygen and hydrogen peroxide. A gene coding for Cu,Zn-SOD was cloned and characterized from Siamese crocodile (Crocodylus siamensis; CSI). The full-length expressed sequence tag (EST) of this Cu,Zn-SOD gene (designated as CSI-Cu,Zn-SOD) contained 462bp encoding a protein of 154 amino acids without signal peptides, indicated as intracellular CSI-Cu,Zn-SOD. This agreed with the results from the phylogenetic tree, which indicated that CSI-Cu,Zn-SOD belonged to the intracellular Cu,Zn-SOD. Chromosomal location determined that the CSI-Cu,Zn-SOD was localized to the proximal region of the Siamese crocodile chromosome 1p. Several highly conserved motifs, two conserved signature sequences (GFHVHEFGDNT and GNAGGRLACGVI), and conserved amino acid residues for binding copper and zinc (His(47), His(49), His(64), His(72), His(81), Asp(84), and His(120)) were also identified in CSI-Cu,Zn-SOD. Real-time PCR analysis showed that CSI-Cu,Zn-SOD mRNA was expressed in all the tissues examined (liver, pancreas, lung, kidney, heart, and whole blood), which suggests a constitutively expressed gene in these tissues. Expression of the gene in Escherichia coli cells followed by purification yielded a recombinant CSI-Cu,Zn-SOD, with Km and Vmax values of 6.075mM xanthine and 1.4×10(-3)mmolmin(-1)mg(-1), respectively. This Vmax value was 40 times lower than native Cu,Zn-SOD (56×10(-3)mmolmin(-1)mg(-1)), extracted from crocodile erythrocytes. This suggests that cofactors, protein folding properties, or post-translational modifications were lost during the protein purification process, leading to a reduction in the rate of enzyme activity in bacterial expression of CSI-Cu,Zn-SOD.

An active recombinant cocoonase from the silkworm Bombyx mori: bleaching, degumming and sericin degrading activities.

BACKGROUND: Cocoonase is a serine protease produced by silk moths and used for softening the cocoons so that they can escape. Degumming is one of the important steps in silk processing. This research aimed to produce an active recombinant Bombyx mori cocoonase (BmCoc) for the silk degumming process. RESULTS: A recombinant BmCoc was successfully expressed in a Pichia pastoris system. The purified enzyme showed specific activity of 227 U mg(-1) protein, 2.4-fold purification, 95% yield and a molecular weight of 26 kDa. The enzyme exhibited optimal temperature at 40 °C and optimal pH at 8, and showed thermal stability at 25-45 °C and pH stability at 5-9. The recombinant enzyme exhibited sericin degumming ability and color bleaching characteristics, and did not affect the fibroin fiber. The enzyme also degraded sericin substrate with a product size about 30-70 kDa. CONCLUSION: In this study, we successfully produced the active recombinant BmCoc in P. pastoris with promising functions for the Thai silk degumming process, which includes degumming, sericin degrading and color bleaching activities. Our data clearly indicated that the recombinant enzyme had proteolytic activity on sericin but not on fibroin proteins. The recombinant BmCoc has proven to be suitable for numerous applications in the silk industry.

Characterization and expression analysis of the transferrin gene in Nile tilapia (Oreochromis niloticus) and its upregulation in response to Streptococcus agalactiae infection.

In this study, full-length tilapia transferrin (OnTF) isolated from liver cDNA of Nile tilapia (Oreochromis niloticus) was found to have an open reading frame of 2,091-bp encoding 696 amino acid residues. Two additional amino acids: Gly(369) and Gly(370) were observed compared with the reported Nile tilapia transferrin protein sequence. Pre-mature protein has a predicted molecular weight of 78.2 kDa, while mature protein is 73.28 kDa in size. Comparative sequence analysis with transferrin from other species revealed two major putative iron-binding domains designated as the N-lobe and the C-lobe in accordance with the transferrin protein characteristics. The predicted tertiary structure of tilapia transferrin confirmed the presence of iron and anion-binding sites on both lobes that are conserved among transferrins from other species. Quantitative real-time PCR analysis showed significantly higher expression of tilapia transferrin gene in liver than in other tissues (p < 0.05). Transferrin expression in tilapia experimentally infected with 10(6) and 10(8) colony-forming units mL(-1) of Streptococcus agalactiae was significantly upregulated at 24 and 12 h post-infection (hpi), respectively, and decreased afterward. Iron-deficiency in serum of bacterially infected fish was detected at 48 and 24 hpi, respectively. The expression pattern of the transferrin gene and the iron levels of infected tilapia in this study were consistent with the function of transferrin in innate immunity.

Computational design of novel chimeric multiepitope vaccine against bacterial and viral disease in tilapia (Oreochromis sp.).

Regarding several infectious diseases in fish, multiple vaccinations are not favorable. The chimeric multiepitope vaccine (CMEV) harboring several antigens for multi-disease prevention would enhance vaccine efficiency in terms of multiple disease prevention. Herein, the immunogens of tilapia's seven pathogens including E. tarda, F. columnare, F. noatunensis, S. iniae, S. agalactiae, A. hydrophila, and TiLV were used for CMEV design. After shuffling and annotating the B-cell epitopes, 5,040 CMEV primary protein structures were obtained. Secondary and tertiary protein structures were predicted by AlphaFold2 creating 25,200 CMEV. Proper amino acid alignment in the secondary structures was achieved by the Ramachandran plot. In silico determination of physiochemical and other properties including allergenicity, antigenicity, glycosylation, and conformational B-cell epitopes were determined. The selected CMEV (OSLM0467, OSLM2629, and OSLM4294) showed a predicted molecular weight (MW) of 70 kDa, with feasible sites of N- and O-glycosylation, and a number of potentially conformational B-cell epitope residues. Molecular docking, codon optimization, and in-silico cloning were tested to evaluate the possibility of protein expression. Those CMEVs will further elucidate in vitro and in vivo to evaluate the efficacy and specific immune response. This research will highlight the new era of vaccines designed based on in silico structural vaccine design.

A reusable screen-printed carbon electrode-based aptasensor for the determination of chloramphenicol in food and environment samples.

An electrochemical aptasensor was developed for the determination of chloramphenicol (CAP) in fresh foods and food products. The aptasensor was developed using Prussian blue (PB) and chitosan (CS) film. PB acts as a redox probe for detection and CS acts as a sorption material. The aptamer (Apt) was immobilized on a screen-printed carbon electrode (SPCE) modified with gold nanoparticles (AuNPs). Under optimum conditions, the linearity of the aptasensor was between 1.0 and 6.0 × 106 ng L-1 with a detection limit of 0.65 and a quantification limit of 2.15 ng L-1. The electrode could be regenerated up to 24 times without the use of chemicals. The aptasensor showed good repeatability (RSD <11.2%) and good reproducibility (RSD <7.7%). The proposed method successfully quantified CAP in milk, shrimp pond water and shrimp meat with good accuracy (recovery = 88.0 ± 0.6% to 100 ± 2%). The proposed aptasensor could be especially useful in agriculture to ensure the quality of food and the environment and could be used to determine other antibiotics.

Evaluation of Bacillus spp. as Potent Probiotics with Reduction in AHPND-Related Mortality and Facilitating Growth Performance of Pacific White Shrimp (Litopenaeus vannamei) Farms.

Acute hepatopancreatic necrosis disease (AHPND) is a serious bacterial disease affecting shrimp aquaculture worldwide. In this study, natural microbes were used in disease prevention and control. Probiotics derived from Bacillus spp. were isolated from the stomachs of AHPND-surviving Pacific white shrimp Litopenaeus vannamei (22 isolates) and mangrove forest soil near the shrimp farms (10 isolates). Bacillus spp. were genetically identified and characterized based on the availability of antimicrobial peptide (AMP)-related genes. The phenotypic characterization of all Bacillus spp. was determined based on their capability to inhibit AHPND-causing strains of Vibrio parahaemolyticus (VPAHPND). The results showed that Bacillus spp. without AMP-related genes were incapable of inhibiting VPAHPND in vitro, while other Bacillus spp. harboring at least two AMP-related genes exhibited diverse inhibition activities. Interestingly, K3 [B. subtilis (srfAA+ and bacA+)], isolated from shrimp, exerted remarkable inhibition against VPAHPND (80% survival) in Pacific white shrimp and maintained a reduction in shrimp mortality within different ranges of salinity (75-95% survival). Moreover, with different strains of VPAHPND, B. subtilis (K3) showed outstanding protection, and the survival rate of shrimp remained stable among the tested groups (80-95% survival). Thus, B. subtilis (K3) was further used to determine its efficiency in shrimp farms in different locations of Vietnam. Lower disease occurrences (2 ponds out of 30 ponds) and greater production efficiency were noticeable in the B. subtilis (K3)-treated farms. Taking the results of this study together, the heat-shock isolation and genotypic-phenotypic characterization of Bacillus spp. enable the selection of probiotics that control AHPND in Pacific white shrimp. Consequently, greater disease prevention and growth performance were affirmed to be beneficial in the use of these probiotics in shrimp cultivation, which will sustain shrimp aquaculture and be environmentally friendly.

Identification of a unique conserved region from a kinetoplastid genome of Leishmania orientalis (formerly named Leishmania siamensis) strain PCM2 in Thailand.

Mitochondrial DNAs (mtDNAs) appear in almost all eukaryotic species and are useful molecular markers for phylogenetic studies and species identification. Kinetoplast DNAs (kDNAs) are structurally complex circular mtDNA networks in kinetoplastids, divided into maxicircles and minicircles. Despite several kDNAs of many Leishmania species being examined, the kDNAs of the new species, Leishmania orientalis (formerly named Leishmania siamensis) strain PCM2, have not been explored. This study aimed to investigate the maxicircle and minicircle DNAs of L. orientalis strain PCM2 using hybrid genome sequencing technologies and bioinformatic analyses. The kDNA sequences were isolated and assembled using the SPAdes hybrid assembler from the Illumina short-read and PacBio long-read data. Circular contigs of the maxicircle and minicircle DNAs were reconstructed and confirmed by BLASTn and rKOMICs programs. The kDNA genome was annotated by BLASTn before the genome comparison and phylogenetic analysis by progressiveMauve, MAFFT, and MEGA programs. The maxicircle of L. orientalis strain PCM2 (18,215 bp) showed 99.92% similarity and gene arrangement to Leishmania enriettii strain LEM3045 maxicircle with variation in the 12s rRNA gene and divergent region. Phylogenetics of the whole sequence, coding regions, divergent regions, and 12s rRNA gene also confirmed this relationship and subgenera separation. The identified 105 classes of minicircles (402-1177 bp) were clustered monophyletically and related to the Leishmania donovani minicircles. The kinetoplast maxicircle and minicircle DNAs of L. orientalis strain PCM2 contained a unique conserved region potentially useful for specific diagnosis of L. orientalis and further exploration of this parasite population genetics in Thailand and related regions.

Cocultures of Enterococcus faecium and Aeromonas veronii Induce the Secretion of Bacteriocin-like Substances against Aeromonas.

Lactic acid bacteria (LAB) were screened from Lutjanus russellii (red sea bass), and their antimicrobial activities were evaluated against two Aeromonas species isolated from the Nile tilapia, namely, Aeromonas veronii (AV) and Aeromonas jandaei (AJ). Three LAB isolates, Enterococcus faecium MU8 (EF_8), Enterococcus faecalis MU2 (EFL_2), and E. faecalis MU9 (EFL_9), were found to inhibit both AV and AJ; however, their cell-free supernatant (CFS) did not do so. Interestingly, bacteriocin-like substances (BLS) induced by cocultures of EF_8 with AV exhibited the highest antimicrobial activity against both Aeromonas sp. The size of BLS was less than 1.0 kDa; the purified BLS were susceptible to proteinase K digestion, indicating that they are peptides. BLS contained 13 identified peptides derived from E. faecium, as determined by liquid chromatography-tandem mass spectrometry. Cocultures of Gram-positive-producing and -inducing LAB strains have been used to increase bacteriocin yields. To our knowledge, this is the first report describing inducible BLS produced by cocultures of Gram-positive-producing and Gram-negative-inducing strains.

Characterisation of thermostable trypsin and determination of trypsin isozymes from intestine of Nile tilapia (Oreochromis niloticus L.).

Trypsin from intestinal extracts of Nile tilapia (Oreochromis niloticus L.) was characterised. Three-step purification - by ammonium sulphate precipitation, Sephadex G-100, and Q Sepharose - was applied to isolate trypsin, and resulted in 3.77% recovery with a 5.34-fold increase in specific activity. At least 6 isoforms of trypsin were found in different ages. Only one major trypsin isozyme was isolated with high purity, as assessed by SDS-PAGE and native-PAGE zymogram, appearing as a single band of approximately 22.39 kDa protein. The purified trypsin was stable, with activity over a wide pH range of 6.0-11.0 and an optimal temperature of approximately 55-60 °C. The relative activity of the purified enzyme was dramatically increased in the presence of commercially used detergents, alkylbenzene sulphonate or alcohol ethoxylate, at 1% (v/v). The observed Michaelis-Menten constant (Km) and catalytic constant (Kcat) of the purified trypsin for BAPNA were 0.16 mM and 23.8 s(-1), respectively. The catalytic efficiency (Kcat/Km) was 238 s(-1) mM(-1).

Identification and Distribution of Wedge Clams (Donacidae: Bivalvia) in Thailand by Geometric Morphometric and Molecular Analysis.

The phylogenetic relationship of living Thai Donacidae was herein studied. Two methodologies, geometric morphometrics (GM) and genetic analysis of COI sequences, were combined and applied to identify the valid taxa and explain biodiversity and the distribution pattern in this family. A total of 587 living specimens were tested to analyze the shape and size patterns by Elliptic Fourier Analysis (EFA). Shell identification and GenBank sequences were added to construct the phylogenetic relationship and haplotype network. Centroid size was used to identify the specimens to the subgenus level. Donax (Hecuba) scortum, was easily distinguished from other species by Principal Component analysis (PCA) of shell size and shape. Donax (Dentilatona) incarnatus and Donax (Deltachion) semisulcatus semisulcatus were identified using Canonical Variates Analysis (CVA). Pairwise comparison of EFA was used for species level recognition, particularly shape overlap was observed for medium and small shell size. Based on genetic distance and haplotype network of COI sequences, Donax (Latona) faba and D. (Latona) solidus could be grouped in the same clade. Intraspecific and interspecific genetic data variation of some common species in different geographical localities of Thailand was observed. Three distribution patterns of Donax species were observed along the two-marine system of Thailand.

Novel Vaccine Development for Fish Culture Based on the Multiepitope Concept.

For the past several decades, aquaculture all around the world have been retarded by various disease outbreaks caused by many pathogens including parasites, bacteria, and viruses. Apart from being harmful to human health, the emerging diseases also dramatically affect the farm animals such as livestock and aquatic animals. To cope with this problem, one of the effective prophylactic measures is the application of vaccine. However, the traditional vaccines still have some limitations and several drawbacks; thus there is a need for the development of novel advanced vaccine such as chimeric multiepitope vaccine. Based on the current understanding of genomics and immunoproteomics together with the present bioinformatics tools, the researchers can identify the potential targeted epitopes being recognizable by the immune cells. Additionally, another critical point that should be considered for designing the chimeric multiepitope vaccine is the exposure of all those epitopes to the host organism. Thus, selecting an appropriate linker and joining each identified epitope in a suitable site can create the ideal protein structure protruding all the selected epitopes on its surface. Herein, our study would provide the fundamental platform to develop the multiepitope B-cell vaccine for the prevention and control of the aquatic animal disease starting with the epitope prediction until in vivo testing the multiepitope vaccine efficacy.

Anti-Protease Activity Deficient Secretory Leukocyte Protease Inhibitor (SLPI) Exerts Cardioprotective Effect against Myocardial Ischaemia/Reperfusion.

Inhibition of proteases shows therapeutic potential. Our previous studies demonstrated the cardioprotection by the Secretory Leukocyte Protease Inhibitor (SLPI) against myocardial ischaemia/reperfusion (I/R) injury. However, it is unclear whether the cardioprotective effect of SLPI seen in our previous works is due to the inhibition of protease enzymes. Several studies demonstrate that the anti-protease independent activity of SLPI could provide therapeutic benefits. Here, we show for the first time that recombinant protein of anti-protease deficient mutant SLPI (L72K, M73G, L74G) (mt-SLPI) could significantly reduce cell death and intracellular reactive oxygen species (ROS) production against an in vitro simulated I/R injury. Furthermore, post-ischaemic treatment of mt-SLPI is found to significantly reduce infarct size and cardiac biomarkers lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) activity, improve cardiac functions, attenuate I/R induced-p38 MAPK phosphorylation, and reduce apoptotic regulatory protein levels, including Bax, cleaved-Caspase-3 and total Capase-8, in rats subjected to an in vivo I/R injury. Additionally, the beneficial effect of mt-SLPI was not significantly different from the wildtype (wt-SLPI). In summary, SLPI could provide cardioprotection without anti-protease activity, which could be more clinically beneficial in terms of providing cardioprotection without interfering with basal serine protease activity.

A Novel Efficient Piscine Oral Nano-Vaccine Delivery System: Modified Halloysite Nanotubes (HNTs) Preventing Streptococcosis Disease in Tilapia (Oreochromis sp.).

Generally, the injection method is recommended as the best efficient method for vaccine applications in fish. However, labor-intensive and difficult injection for certain fish sizes is always considered as a limitation to aquatic animals. To demonstrate the effectiveness of a novel oral delivery system for the piscine vaccine with nano-delivery made from nano clay, halloysite nanotubes (HNTs) and their modified forms were loaded with killed vaccines, and we determined the ability of the system in releasing vaccines in a mimic digestive system. The efficaciousness of the oral piscine vaccine nano-delivery system was evaluated for its level of antibody production and for the level of disease prevention in tilapia. Herein, unmodified HNTs (H) and modified HNTs [HNT-Chitosan (HC), HNT-APTES (HA) and HNT-APTES-Chitosan (HAC)] successfully harbored streptococcal bivalent vaccine with inactivated S. agalactiae, designated as HF, HAF, HCF and HACF. The releasing of the loading antigens in the mimic digestive tract demonstrated a diverse pattern of protein releasing depending on the types of HNTs. Remarkably, HCF could properly release loading antigens with relevance to the increasing pH buffer. The oral vaccines revealed the greatest elevation of specific antibodies to S. agalactiae serotype Ia in HCF orally administered fish and to some extent in serotype III. The efficacy of streptococcal disease protection was determined by continually feeding with HF-, HAF-, HCF- and HACF-coated feed pellets for 7 days in the 1st and 3rd week. HCF showed significant RPS (75.00 ± 10.83%) among the other tested groups. Interestingly, the HCF-treated group exhibited noticeable efficacy similar to the bivalent-vaccine-injected group (RPS 81.25 ± 0.00%). This novel nano-delivery system for the fish vaccine was successfully developed and exhibited appropriated immune stimulation and promised disease prevention through oral administration. This delivery system can greatly support animals' immune stimulation, which conquers the limitation in vaccine applications in aquaculture systems. Moreover, this delivery system can be applied to carrying diverse types of biologics, including DNA, RNA and subunit protein vaccines.