Safety and immunogenicity of the co-administered Na-APR-1 and Na-GST-1 hookworm vaccines in school-aged children in Gabon: a randomised, controlled, observer-blind, phase 1, dose-escalation trial.

BACKGROUND: A human hookworm vaccine is being developed to protect children against iron deficiency and anaemia associated with chronic infection with hookworms. Necator americanus aspartic protease-1 (Na-APR-1) and N americanus glutathione S-transferase-1 (Na-GST-1) are components of the blood digestion pathway critical to hookworm survival in the host. Recombinant Na-GST-1 and catalytically inactive Na-APR-1 (Na-APR-1[M74]) adsorbed to Alhydrogel were safe and immunogenic when delivered separately or co-administered to adults in phase 1 trials in non-endemic and endemic areas. We aimed to investigate the safety and immunogenicity of these antigens in healthy children in a hookworm-endemic area. METHODS: This was a randomised, controlled, observer-blind, phase 1, dose-escalation trial, conducted in a clinical research centre, in 60 children aged six to ten years in Lambaréné, a hookworm-endemic region of Gabon. Healthy children (determined by clinical examination and safety laboratory testing) were randomised 4:1 to receive co-administered Na-GST-1 on Alhydrogel plus Na-APR-1(M74) on Alhydrogel and glucopyranosyl lipid A in aqueous formulation (GLA-AF), or co-administered ENGERIX-B hepatitis B vaccine (HBV) and saline placebo, injected into the deltoid of each arm. Allocation to vaccine groups was observer-masked. In each vaccine group, children were randomised 1:1 to receive intramuscular injections into each deltoid on two vaccine schedules, one at months 0, 2, and 4 or at months 0, 2, and 6. 10 µg, 30 µg, and 100 µg of each antigen were administered in the first, second, and third cohorts, respectively. The intention-to-treat population was used for safety analyses; while for immunogenicity analyses, the per-protocol population was used (children who received all scheduled vaccinations). The primary outcome was to evaluate the vaccines' safety and reactogenicity in healthy children aged between six and ten years. The secondary outcome was to measure antigen-specific serum IgG antibody levels at pre-vaccination and post-vaccination timepoints by qualified ELISAs. The trial is registered with ClinicalTrials.gov, NCT02839161, and is completed. FINDINGS: Between Jan 23 and Oct 3, 2017, 137 children were screened, of whom 76 were eligible for this trial. 60 children were recruited, and allocated to either 10 µg of the co-administered antigens (n=8 for each injection schedule), 30 µg (n=8 for each schedule), 100 µg (n=8 for each schedule), or HBV and placebo (n=6 for each schedule) in three sequential cohorts. Co-administration of the vaccines was well tolerated; the most frequent solicited adverse events were mild-to-moderate injection-site pain, observed in up to 12 (75%) of 16 participants per vaccine group, and mild headache (12 [25%] of 48) and fever (11 [23%] of 48). No vaccine-related serious adverse events were observed. Significant anti-Na-APR-1(M74) and anti-Na-GST-1 IgG levels were induced in a dose-dependent manner, with peaks seen 14 days after the third vaccinations, regardless of dose (for Na-APR-1[M74], geometric mean levels [GML]=2295·97 arbitrary units [AU] and 726·89 AU, while for Na-GST-1, GMLs=331·2 AU and 21·4 AU for the month 0, 2, and 6 and month 0, 2, and 4 schedules, respectively). The month 0, 2, and 6 schedule induced significantly higher IgG responses to both antigens (p=0·01 and p=0·04 for Na-APR-1[M74] and Na-GST-1, respectively). INTERPRETATION: Co-administration of recombinant Na-APR-1(M74) and Na-GST-1 to school-aged Gabonese children was well tolerated and induced significant IgG responses. These results justify further evaluation of this antigen combination in proof-of-concept controlled-infection and efficacy studies in hookworm-endemic areas. FUNDING: European Union Seventh Framework Programme.

Identification of B cell epitopes of Per a 5 allergen using bioinformatic approach.

BACKGROUND: Immune epitopes of allergens are pivotal for development of novel diagnostic and therapeutic modalities. Present study aims to identify antigenic determinants of Per a 5, a clinically relevant cross reactive cockroach allergen. METHODS: The three dimensional structure of Per a 5 was modelled using Modeller 9v11 software. A combination of sequence and structure based computational tools were employed for predicting B cell epitopes. Epitopes were synthesized and immunoreactivity was assessed by ELISA using cockroach hypersensitive patient's sera. Cross-reactivity potential of predicted epitopes was assessed with SDAP and ConSurf and validated by IgE ELISA with fungal and mite hypersensitive patient's sera. RESULTS: Per a 5 structure exhibited good quality factor in ERRAT and high stereochemical stability. In silico analysis revealed six B cell epitopes (BC-P1 to P6). BC-P3 demonstrated significant IgE binding followed by BC-P2 and BC-P1 with cockroach hypersensitive patient's sera. Per a 5 epitopes demonstrate considerable similarity with broad spectrum of allergens from fungal, mites, helminths, fruits and nuts. Analysis of PD values indicate BC-P4 to be well conserved among dust mite and helminth GSTs (8.89, 10.63 and 10.69 with D. pteronyssinus, W. bancrofti and F. hepatica respectively). ConSurf analysis of Per a 5 revealed specific enrichment of evolutionarily similar amino acid residues in BC-P2 (with fungal and mite GSTs) and BC-P4 (with mite and helminth GSTs). Further, IgE binding analysis of epitopes demonstrate BC-P2, BC-P3 and BC-P5 as high IgE binders in fungal hypersensitive sera while BC-P1, BC-P2, BC-P4 and BC-P5 demonstrated significant IgE binding with mite hypersensitive sera. CONCLUSIONS: Among the predicted epitopes, BC-P3 demonstrates maximal IgE binding ability. Computational analysis suggests strong evolutionary conservation and cross reactive potential of BC-P4 with allergens in dust mite and helminths. ELISA highlights predictive potential of analysing evolutionarily conserved residues for uncovering potentially cross reactive antigenic determinants. GENERAL SIGNIFICANCE: Immune epitopes of Per a 5 were identified for aiding molecular diagnosis and potential cross reactivity.

Heat-killed Propionibacterium acnes augment the protective effect of 28-kDa glutathione S-transferases antigen against Schistosoma mansoni infection.

Sm28GST is one of the candidate antigens for Schistosoma mansoni vaccine. Already Sm28GST vaccine formulations have shown to be protective against S. mansoni infection. Currently, efforts have been put into finding an adjuvant to enhance the immunity induced by Sm28GST. In the present work, we investigated whether heat-killed Propionibacterium acnes can be served as a potential adjuvant for recombinant Sm28GST (rSm28GST) antigen. As the results showed, P. acnes successfully modulated the Th1 humoral immune response induced by rSm28GST. Stronger Th1 cytokines responses were also observed in mice immunized with P. acnes-adjuvanted rSm28GST. Immunization of mice with P. acnes-adjuvanted rSm28GST was able to reduce worm burden and hepatic egg burden by 54.20 and 73.61%. Reduced granuloma size and count, as well as improved liver histology, were seen in P. acnes-adjuvanted rSm28GST immunized mice. These data suggest that P. acnes may evoke a stronger rSm28GST-induced immune response, higher resistance to S. mansoni infection, and more profound protection against S. mansoni-induced liver damages.

Bioinformatic and immunological investigation of Per a 5 (delta class GST) allergen from Periplaneta americana.

INTRODUCTION: GSTs are multifunctional enzymes involved in cellular detoxification and present as potent allergens in several sources. Present study investigates allergenic relevance of GST from P. americana and determine its cross reactive potential with other indoor allergen sources. METHODS: Computational analysis with FASTA and ConSurf webserver was performed to determine potentially cross reactive allergens. Further, Per a 5 gene was cloned in pET 22b+ vector and expressed in E.coli BL21 cells and the rPer a 5 protein was purified using Ni-NTA affinity chromatography. Enzymatic activity of rPer a 5 was assessed using CDNB and cumene hydroperoxide. ELISA and immunoblot were performed using cockroach hypersensitive patient's sera. Functional activity of rPer a 5 was evaluated by basophil activation test. Inhibition studies were carried out with D. pteronyssinus, A. alternata and C. lunata extracts. RESULTS: Per a 5 demonstrates highest sequence similarity with delta class GST of Blattella germanica (94.9%). It also exhibits significant sequence similarity (50-58%) with mite, fungal and helminth allergenic GSTs. ConSurf analysis reveals high degree of evolutionary similarity in N terminal region of Per a 5, especially at GST dimerization interface. The purified rPer a 5 protein resolved at 27 kDa on SDS-PAGE. The rPer a 5 protein exhibits GST activity and possess upto 65% immunoreactivity with cockroach hypersensitive patient's sera in ELISA and immunoblot. It upregulates expression of CD203c on basophils signifying its biological ability to activate effector cells. rPer a 5 significantly inhibits corresponding GSTs in P. americana, D. pteronyssinus, A. alternata and C. lunata with EC50 values of 15.5 ng. 38.38 ng, 41.4 ng and 61.66 ng, respectively. CONCLUSION: Recombinant delta class GST of P. americana is a clinically relevant allergen showing upto 65% immunoreactivity with hypersensitive patient's sera. Per a 5 GST allergen showed phylogenetic similarity with dust mite, fungal and birch allergens thereby demonstrating allergen cross reactivity.

Molecular characterization, immune and xenobiotic responses of glutathione S-transferase omega 1 from the big-belly seahorse: Novel insights into antiviral defense.

Glutathione S-transferases (GSTs) are important enzymes involved in phase II detoxification and function by conjugating with the thiol group of glutathione. In this study, we isolated an omega class GST from the big-belly seahorse (Hippocampus abdominalis; HaGSTO1) to study the putative xenobiotic responses and defense ability against viral and bacterial infections in this animal. The isolated HaGSTO1 gene, with a cording sequence of 720 bp, encodes a peptide of 239 amino acids. The predicted molecular mass and theoretical isoelectric point of HaGSTO1 was 27.47 kDa and 8.13, respectively. In-silico analysis of HaGSTO1 revealed a characteristic N-terminal thioredoxin-like domain and a C-terminal domain. Unlike other GSTs, the C-terminal of HaGSTO1 reached up to the N-terminal, and the N-terminal functional group was cysteine rather than tyrosine or serine, as observed in other GSTs. Phylogenetic analysis showed the evolutionary proximity of HaGSTO1 with other identified vertebrate and invertebrate GST orthologs. For the first time, we demonstrated the viral defense capability of HaGSTO1 against viral hemorrhagic septicemia virus (VHSV) infection. All six nucleoproteins of VHSV were significantly downregulated in HaGSTO1-overexpressing FHM cells at 24 h after infection compared with those in the control. Moreover, arsenic toxicity was significantly reduced in HaGSTO1-overexpressing FHM cells, and cell viability increased. Real-time polymerase chain reaction analysis showed that HaGSTO1 transcripts were highly expressed in the pouch and gill when compared with those in other tissues. Blood HaGSTO1 transcripts were significantly upregulated after Edwardsiella tarda, Streptococcus iniae, lipopolysaccharide, and polyinosinic:polycytidylic acid challenge experiments. Collectively, these findings suggest the involvement of HaGSTO1 in the host defense mechanism of seahorses.

Transcriptome sequencing reveals Cnaphalocrocis medinalis against baculovirus infection by oxidative stress.

Cnaphalocrocis medinalis granulovirus (CnmeGV) is a potential microbial agent against the rice leaffolder. Innate immunity is essential for insects to survive pathogenic infection. Therefore, to clarify the immune response of Cnaphalocrocis medinalis to the viral colonization, the gene expression profile of C. medinalis infected with CnmeGV was constructed by RNA-seq. A total of 8,503 differentially expressed genes (DEGs) were found including 5,304 up-regulated and 3,199 down-regulated unigenes. Gene enrichment analysis indicated that these DEGs were mainly linked to protein synthesis and metabolic process as well as ribosome and virus-infection pathways. Specifically, a significantly up-regulated PiggyBac-like transposon gene was identified suggested that the enhancement of transposon activity is related to host immunity. Further, the DEGs encoding oxidative stress related genes were identified and validated by RT-qPCR. Overall, 9 antioxidant enzyme genes and 4 antioxidant protein genes were up-regulated, and the extensive glutathione S-transferase genes were down-regulated. Our results provide a basis for understanding the molecular mechanisms of baculovirus action and oxidative stress response in C. medinalis and other insects.

Characterisation of a Teladorsagia circumcincta glutathione transferase.

A 615 bp full length cDNA encoding a Teladorsagia circumcincta glutathione transferase (TcGST) was cloned, expressed in Escherichia coli and the recombinant protein purified and its kinetic properties determined. The predicted protein consisted of 205 amino acids and was present as a single band of about 24 kDa on SDS-PAGE. Multiple alignments of the protein sequence of TcGST with homologues from other helminths showed that the highest identity of 53-68% with haem-binding nematode proteins designated as members of the nu class of GSTs. Substrate binding sites and conserved regions were identified and were generally conserved. The predicted 3-dimensional structures of TcGST and HcGST revealed highly open binding cavities typical of this class of GST, considered to allow greater accessibility to diverse ligands compared with other classes of GST. At 25 °C, the optimum pH for TcGST activity was pH 7, the Vmax was 1535 ± 33 nmoles.min-1. mg-1 protein and the apparent Km for the substrate 1-chloro-2,4-dinitrobenzene (CDNB) was 0.22 ± 0.01 mM (mean ± SD, n = 2). Antibodies in both serum and saliva from field-immune, but not nematode-naïve, sheep, recognised recombinant TcGST in enzyme-linked immunosorbent assays. The recognition of the recombinant protein by antibodies generated by exposure of sheep to the native enzyme indicates similar antigenicity of the two proteins. These findings could aid in the design of novel drugs and vaccine antigens for economically important parasites of livestock.

Designing a vaccine for fascioliasis using immunogenic 24 kDa mu-class glutathione s-transferase.

Fascioliasis, caused by the liver fluke Fasciola gigantica, is a significant zoonotic disease of the livestock and human, causing substantial economic loss worldwide. Triclabendazole (TCBZ) is the only drug available for the management of the disease against which there is an alarming increase in drug resistance. No vaccine is available commercially for the protection against this disease. Increasing resistance to TCBZ and the lack of a successful vaccine against fascioliasis demands the development of vaccines. In the present study, a structural immunoinformatics approach was used to design a multi-epitope subunit vaccine using the glutathione S-transferase (GST) protein of Fasciola gigantica. The GST antigen is a safe, non-allergic, highly antigenic, and effective vaccine candidate against various parasitic flukes and worms. The cytotoxic T lymphocytes, helper T lymphocytes, and B-cell epitopes were selected for constructing the vaccine based on their immunogenic behavior and binding affinity. The physicochemical properties, allergenicity, and antigenicity of the designed vaccine were analyzed. To elucidate the tertiary structure of the vaccine, homology modeling was performed, followed by structure refinement and docking against the TLR2 immune receptor. Molecular dynamics simulations showed a stable interaction between the vaccine and the receptor complex. Finally, in silico cloning was performed to evaluate the expression and translation of the vaccine construct in the E. coli expression system. Further studies require experimental validation for the safety and immunogenic behavior of the designed vaccine.

Prediction, mapping and validation of tick glutathione S-transferase B-cell epitopes.

In search of ways to address the increasing incidence of global acaricide resistance, tick control through vaccination is regarded as a sustainable alternative approach. Recently, a novel cocktail antigen tick-vaccine was developed based on the recombinant glutathione S-transferase (rGST) anti-sera cross-reaction to glutathione S-transferases of Rhipicephalus appendiculatus (GST-Ra), Amblyomma variegatum (GST-Av), Haemaphysalis longicornis (GST-Hl), Rhipicephalus decoloratus (GST-Rd) and Rhipicephalus microplus (GST-Rm). Therefore, the current study aimed to predict the shared B-cell epitopes within the GST sequences of these tick species. Prediction of B-cell epitopes and proteasomal cleavage sites were performed using immunoinformatics algorithms. The conserved epitopes predicted within the sequences were mapped on the homodimers of the respective tick GSTs, and the corresponding peptides were independently used for rabbit immunization experiments. Based on the dot blot assay, the immunogenicity of the peptides and their potential to be recognized by corresponding rGST anti-sera raised by rabbit immunization in a previous work were investigated. This study revealed that the predicted conserved B-cell epitopes within the five tick GST sequences were localized on the surface of the respective GST homodimers. The epitopes of GST-Ra, GST-Rd, GST-Av, and GST-Hl were also shown to contain a seven residue-long peptide sequence with no proteasomal cleavage sites, whereas proteasomal digestion of GST-Rm was predicted to yield a 4-residue fragment. Given that a few proteasomal cleavage sites were found within the conserved epitope sequences of the four GSTs, the sequences could also contain a T-cell epitope. Finally, the peptide and rGST anti-sera reacted against the corresponding peptide, confirming their immunogenicity. These data support the claim that the rGSTs, used in the previous study, contain conserved B-cell epitopes, which elucidates why the rGST anti-sera cross-reacted to non-homologous tick GSTs. Taken together, the data suggest that the B-cell epitopes predicted in this study could be useful for constituting epitope-based GST tick vaccines.

A Sensitive and Simple Enzyme-Linked Immunosorbent Assay Using Polymer as Carrier.

In this study, a new and sensitive enzyme-linked immunosorbent assay (ELISA) was developed by introducing a polymer as a reaction carrier. The results suggest that the newly developed ELISA method is more convenient than the existing paper-based ELISA method and applicable to a wider range of environments. In addition, the sensitivity of the new method is much higher than that of the existing paper-based ELISA method and even higher than that of the traditional ELISA method.

GSTO1-1 is an upstream suppressor of M2 macrophage skewing and HIF-1α-induced eosinophilic airway inflammation.

BACKGROUND: Glutathione S-transferases omega class 1 (GSTO1-1) is a unique member of the GST family regulating cellular redox metabolism and innate immunity through the promotion of LPS/TLR4/NLRP3 signalling in macrophages. House dust mite (HDM) triggers asthma by promoting type 2 responses and allergic inflammation via the TLR4 pathway. Although linked to asthma, the role of GSTO1-1 in facilitating type 2 responses and/or HDM-driven allergic inflammation is unknown. OBJECTIVE: To determine the role of GSTO1-1 in regulating HDM-induced allergic inflammation in a preclinical model of asthma. METHODS: Wild-type and GSTO1-1-deficient mice were sensitized and aeroallergen challenged with HDM to induce allergic inflammation and subsequently hallmark pathophysiological features characterized. RESULTS: By contrast to HDM-challenged WT mice, exposed GSTO1-1-deficient mice had increased numbers of eosinophils and macrophages and elevated levels of eotaxin-1 and -2 in their lungs. M1 macrophage-associated factors, such as IL-1ß and IL-6, were decreased in GSTO1-1-deficient mice. Conversely, M2 macrophage factors such as Arg-1 and Ym1 were up-regulated. HIF-1α expression was found to be higher in the absence of GSTO1-1 and correlated with the up-regulation of M2 macrophage markers. Furthermore, HIF-1α was shown to bind and activate the eotaxin-2 promotor. Hypoxic conditions induced significant increases in the levels of eotaxin-1 and -2 in GSTO1-deficient BMDMs, providing a potential link between inflammation-induced hypoxia and the regulation of M2 responses in the lung. Collectively, our results suggest that GSTO1-1 deficiency promotes M2-type responses and increased levels of nuclear HIF-1α, which regulates eotaxin (s)-induced eosinophilia and increased disease severity. CONCLUSION & CLINICAL IMPLICATION: We propose that GSTO1-1 is a novel negative regulator of TLR4-regulated M2 responses acting as an anti-inflammatory pathway. The discovery of a novel HIF-1α-induced eotaxin pathway identifies an unknown connection between hypoxia and the regulation of the severity of allergic inflammation in asthma.

Identification of linear epitopes in SjSP-13 of Schistosoma japonicum using a GST-peptide fusion protein microplate array.

BACKGROUND: The identification and characterization of epitopes facilitate the discovery and development of new therapeutics, vaccines and diagnostics for infectious diseases. In this study, we developed a glutathione S-transferase (GST)-peptide fusion protein microplate array for the identification of linear B-cell epitopes and applied this novel method to the identification of linear B-cell epitopes of SjSP-13, an immunodiagnostic biomarker of schistosomiasis japonica. METHODS: SjSP-13 was divided into 17 overlapped peptides (p1-17), and the coding sequence of each peptide was obtained by annealing two complementary oligonucleotides. SjSP-13 peptides were expressed by fusion with an N-terminal GST tag and a C-terminal 6xHis tag. The GST-peptide-His fusion protein was specifically bound to the Immobilizer Glutathione MicroWell 96-well plates without purification. SjSP-13 peptides and core epitopes that could be recognized by sera from schistosomiasis patients were identified by ELISA and confirmed by Western blot analysis. The receiver operating characteristic (ROC) analysis was performed to determine the diagnostic validity of the identified peptide. RESULTS: Full-length GST-peptide-His fusion proteins were successfully expressed and specifically bound to the Immobilizer Glutathione MicroWell 96-well plates. Two adjacent peptides (p7 and p8) were found to be highly immunogenic in humans. The core epitope of p7 and p8 is an 11-aa peptide (80KCLDVTDNLPE90) and an 8-aa peptide (90EKIIQFAE97), respectively. The area under the ROC curve (AUC) value of the peptide which contains the two identified epitopes is 0.947 ± 0.019. The diagnostic sensitivity and specificity of the peptide is 76.7% (95% CI: 68.8-84.5%) and 100%, respectively. CONCLUSIONS: 90EKIIQFAE97 and 80KCLDVTDNLPE90 are the two linear epitopes of SjSP-13 recognized by patient sera, and could be potential serological markers for schistosomiasis japonica.

Glutathione-S-transferase of Trichinella spiralis regulates maturation and function of dendritic cells.

Immunomodulation by molecules from Trichinella spiralis (T. spiralis) has been widely reported. Glutathione-S-transferase (GST) is a major immune-modulator of the family of detoxification enzymes. Dendritic cells (DCs) are an important target for the regulation of the immune response by T. spiralis. In this study, the recombinant GST of T. spiralis (rTs-GST) was expressed and purified. rTs-GST induced low CD40 expression and moderate CD80, CD86 and MHC-II expressions and inhibited the increase of CD40, CD80 and CD86 on DCs induced by LPS. We showed that rTs-GST decreased the LPS-induced elevated level of pro-inflammatory cytokines of DCs and enhanced the level of regulatory cytokines IL-10 and TGF-ß. Furthermore, co-culture of DCs and CD4+ T cells demonstrated that rTs-GST-treated DCs suppressed the proliferation of OVA-specific CD4+ T cells and increased the population of regulatory T cells (Tregs). rTs-GST-treated DCs induced a higher level of IL-4, IL-10 and TGF-ß, but inhibited the level of IFN-γ. This indicates that rTs-GST-pulsed DCs induce both Th2-type responses and Tregs. These findings contribute to the current understanding of the immunomodulation of Ts-GST on cellular response and immunomodulation of T. spiralis.

Development and Characterization of Monoclonal Antibodies to Botulinum Neurotoxin Type E.

Botulism is a devastating disease caused by botulinum neurotoxins (BoNTs) secreted primarily by Clostridium botulinum. Mouse bioassays without co-inoculation with antibodies are the standard method for the detection of BoNTs, but are not capable of distinguishing between the different serotypes (A-G). Most foodborne intoxications are caused by serotypes BoNT/A and BoNT/B. BoNT/E outbreaks are most often observed in northern coastal regions and are associated with eating contaminated marine animals and other fishery products. Sandwich enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of BoNT/E3. Monoclonal antibodies (mAbs) were generated against BoNT/E3 by immunizing with recombinant peptide fragments of the light and heavy chains of BoNT/E3. In all, 12 mAbs where characterized for binding to both the recombinant peptides and holotoxin, as well as their performance in Western blots and sandwich ELISAs. The most sensitive sandwich assay, using different mAbs for capture and detection, exhibited a limit of detection of 0.2 ng/ml in standard buffer matrix and 10 ng/mL in fish product matrices. By employing two different mAbs for capture and detection, a more standardized sandwich assay was constructed. Development of sensitive and selective mAbs to BoNT/E would help in the initial screening of potential food contamination, speeding diagnosis and reducing use of laboratory animals.

Molecular characterization and functional analysis of glutathione S-transferase kappa 1 (GSTκ1) from the big belly seahorse (Hippocampus abdominalis): Elucidation of its involvement in innate immune responses.

Glutathione S-transferases (GSTs) are essential enzymes for the bioactivation of xenobiotics through the conjugation of the thiol group of glutathione (GSH). In this study, a kappa class of GST was identified from the big belly seahorse (Hippocampus abdominalis) (HaGSTκ1) and its biochemical and functional properties were analyzed. HaGSTκ1 has 231 amino acids encoded by a 696 bp open reading frame (ORF). The protein has a predicted molecular mass of 26.04 kDa and theoretical isoelectric point (pI) of 8.28. It comprised a thioredoxin domain, disulfide bond formation protein A (DsbA) general fold, and Ser15 catalytic site as well as GSH-binding and polypeptide-binding sites. Phylogenetic analysis revealed that HaGSTκ1 is closely clustered with the kappa class of GSTs from teleost fishes. The recombinant (rHaGSTκ1) protein exhibited activity toward 1-chloro-2,4-dinitrobenzene (CDNB), 4-nitrobenzyl (4-NBC), and 4-nitrophenethyl bromide (4-NPB) but not 1,2-dichloro-4-nitrobenzene (DCNB). The optimum pH and temperature were 8 and 30 °C, respectively, for the catalysis of CDNB and the universal substrate of GSTs. The rHaGSTκ1 activity was efficiently inhibited in the presence of Cibacron blue (CB) as compared with hematin. Most prominent expression of HaGSTκ1 was observed in the liver and kidney among the fourteen different tissues of normal seahorse. After challenge with lipopolysaccharide (LPS), polyinosinic-polycytidylic (poly I:C), gram-negative Edwardsiella tarda, and gram-positive Streptococcus iniae, HaGSTκ1 expression was significantly modulated in the liver and blood tissues. Altogether, our study proposes the plausible important role of HaGSTκ1 in innate immunity and detoxification of harmful xenobiotics.

Administration of anti-CTLA-4 monoclonal antibody augments protective immunity induced by Schistosoma japonicum glutathione-S-transferase.

AIMS: The aim of this study was to evaluate the effect of anti-CTLA-4 monoclonal antibody (mAb) on 26-kDa glutathione-S-transferase (GST) vaccine-induced immunity against Schistosoma japonicum infection. METHODS AND RESULTS: Mice immunized with GST before infection with S japonicum cercariae were injected with anti-CTLA-4 mAb. Worm reduction rate of GST was increased from 25.41% in mice with GST immunization to 52.48% in mice with GST plus anti-CTLA-4 mAb. The percentages of regulatory T cells (Tregs) were significantly higher following administration of both GST and anti-CTLA-4 mAb, or anti-CTLA-4 mAb alone. Elevated levels of IFN-γ, IL-2, IL-4 and IL-5 were observed. CONCLUSION: These results demonstrated that CTLA-4 may inhibit the protective effect of GST vaccine, and anti-CTLA-4 mAb may be used as an adjuvant to enhance the immune protection conferred by the GST vaccine by enhancing Th1- and Th2-type immune response.

Immune and xenobiotic responses of glutathione S-Transferase theta (GST-θ) from marine invertebrate disk abalone (Haliotis discus discus): With molecular characterization and functional analysis.

Representing a multifunctional complex group of proteins, glutathione S- transferases (GSTs) play a major role in the phase II detoxification process in a wide range of organisms. This study focused on the potential detoxification ability of disk abalone (Haliotis discus discus) GST theta (AbGST-θ) under different stress conditions with special reference to post immune challenges. Characterization of AbGST-θ revealed with 226 amino acids, 26.6 kDa of predicted molecular mass and 8.9 of theoretical isoelectric point. As illustrated in the multiple sequence alignment, eight glutathione binding sites (G-sites) and ten substrate binding sites (H-sites) were identified in well-distinct N-terminal and C-terminal domains of AbGST-θ, respectively. AbGST-θ exhibited its highest sequence identity with Mizuhopecten yessoensis (59.1%) and the phylogenetic tree clearly positioned AbGST-θ with pre-defined GST-θ molluscan homologues. The AbGST-θ was highly expressed in the digestive tract of un-challenged abalones. Upon administering the challenge experiment, AbGST-θ showed significant modulations in their transcriptional levels depending on the time and the tissue type. The optimum temperature was 37 °C and optimum pH was 7.5 for AbGST-θ. The determined enzyme kinetic parameters of AbGST-θ showed low affinity towards 1-Chloro-2,4-dinitrobenzene (CDNB) and glutathione (GSH) as substrates. Nonetheless, with Cibacron blue IC50 (half maximal inhibitory concentration) was calculated to be 0.08 µM while observing 100% inhibition with 100 µM. Furthermore, AbGST-θ resulted in significant protection ability towards H2O2, CdCl2, and ZnCl2 in the disk diffusion assay. Collectively, this study provides evidences for the detoxification ability and the immunological host defensive capability of AbGST-θ in disk abalone.

Neospora GRA6 possesses immune-stimulating activity and confers efficient protection against Neospora caninum infection in mice.

Vaccination has the potential to be the most cost-effective control measure for reducing the economic burden of neosporosis in cattle. In this study, the immune-stimulatory effect of recombinant Neospora caninum dense granule protein 6 (NcGRA6) was confirmed via its triggering of IL-12p40 production in murine macrophages. BALB/c mice were immunized with recombinant NcGRA6 fused with glutathione S-transferase (GST) protein with or without oligomannose-coated-liposomes (OMLs) as the potential adjuvant. Specific IgG1 antibody production was observed from 21 and 35 days after the first immunization in NcGRA6+GST- and NcGRA6+GST-OML-immunized mice, respectively. However, specific IgG2a was detected 1 week after the infection, and IgG2a levels of the NcGRA6+GST- group were higher than those of the NcGRA6+GST-OML-group. Moreover, spleen cell proliferation with concomitant interferon-gamma production was detected in mice immunized with NcGRA6+GST, indicating that a significant cellular immune response was induced. Mouse survival rates against N. caninum challenge infection were 91.7% for NcGRA6+GST and 83.3% for NcGRA6+GST-OML, which were significantly higher than those of control groups (GST-OML: 25%, phosphate-buffered saline: 16.7%). This indicates that naked NcGRA6+GST induced protective immunity. Thus, our findings highlight the immune-stimulating potential of NcGRA6 and the ability to induce protective immunity against N. caninum infection in mice.

Constituting a glutathione S-transferase-cocktail vaccine against tick infestation.

Cocktail vaccines are proposed as an attractive way to increase protection efficacy against specific tick species. Furthermore, such vaccines made with different tick antigens have the potential of cross-protecting against a broad range of tick species. However, there are still limitations to the selection of immunogen candidates. Acknowledging that glutathione S-transferases (GSTs) have been exploited as vaccines against ticks and other parasites, this study aimed to analyze a GST-cocktail vaccine as a potential broad-spectrum tick vaccine. To constitute the GST-cocktail vaccine, five tick species of economic importance for livestock industry were studied (Rhipicephalus appendiculatus, Rhipicephalus decoloratus, Rhipicephalus microplus, Amblyomma variegatum, and Haemaphysalis longicornis). Tick GST ORF sequences were cloned, and the recombinant GSTs were produced in Escherichia coli. rGSTs were purified and inoculated into rabbits, and the immunological response was characterized. The humoral response against rGST-Rd and rGST-Av showed a stronger cross-reactivity against heterologous rGSTs compared to rGST-Hl, rGST-Ra, and rGST-Rm. Therefore, rGST-Rd and rGST-Av were selected for constituting an experimental rGST-cocktail vaccine. Vaccination experiment in rabbits showed that rGST-cocktail caused 35% reduction in female numbers in a Rhipicephalus sanguineus infestation. This study brings forward an approach to selecting immunogens for cocktail vaccines, and the results highlight rGST-Rd and rGST-Av as potentially useful tools for the development of a broad-spectrum tick vaccine.