Formation and immunological evaluation of Moraxella catarrhalis glycoconjugates based on synthetic oligosaccharides

Published work has shown that glycoconjugate vaccines, based on truncated detoxified lipopolysaccharides from Moraxella catarrhalis attached through their reducing end to a carrier protein, gave good protection for all three serotypes A, B, and C in mice immunisation experiments. The (from the non-reducing end) truncated LPS structures were obtained from bacterial glycosyl transferase knock-out mutants and contained the de-esterified Lipid A, two Kdo residues and five glucose moieties. This work describes the chemical synthesis of the same outer Moraxella LPS structures, spacer-equipped and further truncated from the reducing end, i.e., without the Lipid A part and containing four or five glucose moieties or four glucose moieties and one Kdo residue, and their subsequent conjugation to a carrier protein via a five‑carbon bifunctional spacer to form glycoconjugates. Immunisation experiments both in mice and rabbits of these gave a good antibody response, being 2-7 times that of pre-immune sera. However, the sera produced only recognized the immunizing glycan immunogens and failed to bind to native LPS or whole bacterial cells. Comparative molecular modelling of three alternative antigens shows that an additional (2 → 4)-linked Kdo residue, not present in the synthetic structures, has a significant impact on the shape and volume of the molecule, with implications for antigen binding and cross-reactivity.

Influence of glycosylation on the immunogenicity and antigenicity of viral immunogens

A key aspect of successful viral vaccine design is the elicitation of neutralizing antibodies targeting viral attachment and fusion glycoproteins that embellish viral particles. This observation has catalyzed the development of numerous viral glycoprotein mimetics as vaccines. Glycans can dominate the surface of viral glycoproteins and as such, the viral glycome can influence the antigenicity and immunogenicity of a candidate vaccine. In one extreme, glycans can form an integral part of epitopes targeted by neutralizing antibodies and are therefore considered to be an important feature of key immunogens within an immunization regimen. In the other extreme, the existence of peptide and bacterially expressed protein vaccines shows that viral glycosylation can be dispensable in some cases. However, native-like glycosylation can indicate native-like protein folding and the presence of conformational epitopes. Furthermore, going beyond native glycan mimicry, in either occupancy of glycosylation sites or the glycan processing state, may offer opportunities for enhancing the immunogenicity and associated protection elicited by an immunogen. Here, we review key determinants of viral glycosylation and how recombinant immunogens can recapitulate these signatures across a range of enveloped viruses, including HIV-1, Ebola virus, SARS-CoV-2, Influenza and Lassa virus. The emerging understanding of immunogen glycosylation and its control will help guide the development of future vaccines in both recombinant protein- and nucleic acid-based vaccine technologies.

Immunisation with Neospora caninum subunits rsNcSAG4 and rsNcGRA1 (NcSAG4 and NcGRA1 epitopes construct) in BALB/c mice: the profile of the immune response and controlling the vertical transmission

Neospora caninum is an apicomplexan protozoan that causes neosporosis, which has a high economic impact on cattle herds with no available vaccine. During infection, the secretion of dense granules and the expression of surface antigens play an important role in hosting immunomodulation. However, some epitopes of those antigens are immunogenic, and using these fractions could improve the subunit antigens in vaccine design. This study evaluates the recombinant peptides rsNcGRA1 and rsNcSAG4 derived from NcGRA1 and NcSAG4 native antigens as vaccine candidates produced by a fermentative process in the yeast culture system of Komagataella phaffii strain Km71, confirmed by colony PCR, SDS-PAGE, and western blotting. The assay was conducted in BALB/c mice using the peptides at low (25 μg) and standard (50 μg) dosages in monovalent and combined administrations at three time points with saponin as an adjuvant assessing the immunogenicity by antibodies response and cytokine production. We challenge the females after pregnancy confirmation using 2 × 105 NC-1 tachyzoites previously propagated in Vero cells. We assessed the chronic infection in dams and vertical transmission in the offspring by PCR and histopathology. Mice, especially those immunised with combined peptides and monovalent rsNcGRA1 at a standard dose, controlling the chronic infection in dams with the absence of clinical manifestations, showed an immune response with induction of IgG1, a proper balance between Th1/Th2 cytokines and reduced vertical transmission in the pups. In contrast, dams inoculated with a placebo vaccine showed clinical signs, low-scored brain lesions, augmented chronic infection with 80% positivity, 31% mortality in pups, and 81% vertical transmission. These findings indicate that rsNcGRA1 peptides in monovalent and combined with rsNCSAG4 at standard dose are potential vaccine candidates and improve the protective immune response against neosporosis in mice.

Pentavalent outer membrane vesicles immunized mice sera confers passive protection against five prevalent pathotypes of diarrhoeagenic Escherichia coli in neonatal mice

Diarrhoeagenic Escherichia coli (DEC) pathotypes are one of the major causative agents of diarrhoea induced childhood morbidity and mortality in developing countries. Licensed vaccines providing broad spectrum protection against DEC mediated infections are not available. Outer membrane vesicles (OMVs) are microvesicles released by gram-negative bacteria during the growth phase and contain multiple immunogenic proteins. Based on prevalence of infections, we have formulated a pentavalent outer-membrane vesicles (POMVs) based immunogen targeting five main pathotypes of DEC responsible for diarrhoeal diseases. Following isolation, OMVs from five DEC pathotypes were mixed in equal proportions to formulate POMVs and 10 µg of the immunogen was intraperitoneally administered to adult BALB/c mice. Three doses of POMVs induced significant humoral immune response against whole cell lysates (WCLs), outer membrane proteins (OMPs) and lipopolysaccharides (LPS) isolated from DEC pathotypes along with significant induction of cellular immune response in adult mice. Passive transfer of POMVs immunized adult mice sera protected neonatal mice significantly against DEC infections. Overall, this study finds POMVs to be immunogenic in conferring broad-spectrum passive protection to neonatal mice against five main DEC pathotypes. Altogether, these findings suggest that POMVs can be used as a potent vaccine candidate to ameliorate the DEC-mediated health burden.

Impact of bridge heterology on functional parameters of ELISA for 17α-methyltestosterone

In this study, we have developed bridge heterologous ELISA for the detection of 17α- Methyltestosterone by incorporating aromatic spacers between 17α-Methyltestosterone-3-Carboxymethyloxime and Horseradish peroxidase label through N-hydroxysuccinimide mediated carbodiimide reaction method. The immunogen 17α-Methyltestosterone-3-Carboxymethyloxime-Bovine serum albumin used to generate the antibody was also prepared by the N-hydroxysuccinimide mediated carbodiimide reaction without using any spacer. We have studied the impact of bridge/aromatic spacers on functional parameters i.e. sensitivity, affinity and ED50 of the bridge heterologous assay and compared it with homologous assay. The five combinations of bridge heterologous assay using 17α-Methyl testosterone-3-CMO-BSA antiserum and 17α-MT-3-CMO-4,4'-Diaminodiphenyl sulphide-HRP, 17α MT-3-CMO-4,4'-Oxydianiline-HRP, 17α-MT-3-CMO-Benzidine-HRP, 17α- MT-3-CMO-p-Phenylenediamine-HRP and 17α-MT-3-CMO-Dapson-HRP enzyme conjugates were evaluated. Out of these five combinations, the combination 17α-MT-3-CMO-BSA with 17α-MT-3-CMO-Benzidine-HRP showed the best results. Sensitivity, affinity and ED50 were improved and found to be 0.02 ng/mL, 0.086 × 10-8 L/mol and 2.95 ng/mL than homologous assay where Sensitivity, affinity and ED50 were 0.11 ng/mL, 0.02 × 10-8 L/mol and 5.78 ng/mL respectively. The cross-reactivity for this bridge heterologous assay combination was seen with only 4 steroids (6-hydrotestosterone- 6%, Testosterone-5.14%, Danazol-0.9% and Nandrolone-0.85%) instead of eight steroids (6-hydrotestosterone-43.75%, Testosterone-38.3%, Danazol-25.14%, Androstenediol-19.16%, Nandrolone-19%, Metandienone-5%, Androstenedione-3.52%, and 17α dimethyltestosterone-2%) as in homologous assay out of 59 structurally related steroids. Thus, the results of this study conclude that the incorporation of aromatic spacer (bridge) in enzyme conjugate has a crucial role in improving sensitivity, specificity, ED50 and affinity of the developed assay. The assay was then studied for parameters such as recovery (97.4%-108.6%), precision (Inter and Intra-assay coefficient of variation <10%), correlation coefficient (R2 = 0.96) by comparing with the commercial kit and validated by measuring levels of 17α- methyltestosterone in rat serum after administering them.

HtrA is involved in stress response and adhesion in Glaesserella parasuis serovar 5 strain Nagasaki

Glaesserella parasuis is an important pathogen that causes fibrinous polyserositis, peritonitis and meningitis in pigs, leading to considerable economic losses to the swine industry worldwide. It is well established that the serine protease HtrA is closely associated with bacterial virulence, but the role of HtrA in G. parasuis pathogenesis remains largely unknown. To characterize the function of the htrA gene in G. parasuis, a ΔhtrA mutant was constructed. We found that the ΔhtrA mutant showed significant growth inhibition under heat shock and alkaline stress conditions, indicating HtrA is involved in stress tolerance and survival of G. parasuis. In addition, deletion of htrA gene resulted in decreased adherence to PIEC and PK-15 cells and increased phagocytic resistance to 3D4/2 macrophages, suggesting that htrA is essential for adherence of G. parasuis. Scanning electron microscopy revealed morphological surface changes of the ΔhtrA mutant, and transcription analysis confirmed that a number of adhesion-associated genes are downregulated, which corroborated the aforementioned phenomenon. Furthermore, G. parasuis HtrA induced a potent antibody response in piglets with Glässer's disease. These observations confirmed that the htrA gene is related to the survival and pathogenicity of G. parasuis.

Generation and characterisation of a semi-synthetic siderophore-immunogen conjugate and a derivative recombinant triacetylfusarinine C-specific monoclonal antibody with fungal diagnostic application

Invasive pulmonary aspergillosis (IPA) is a severe life-threatening condition. Diagnosis of fungal disease in general, and especially that caused by Aspergillus fumigatus is problematic. A. fumigatus secretes siderophores to acquire iron during infection, which are also essential for virulence. We describe the chemoacetylation of ferrated fusarinine C to diacetylated fusarinine C (DAFC), followed by protein conjugation, which facilitated triacetylfusarinine C (TAFC)-specific monoclonal antibody production with specific recognition of the ferrated form of TAFC. A single monoclonal antibody sequence was ultimately elucidated by a combinatorial strategy involving protein LC-MS/MS, cDNA sequencing and RNAseq. The resultant murine IgG2_a monoclonal antibody was secreted in, and purified from, mammalian cell culture (5 mg) and demonstrated to be highly specific for TAFC detection by competitive ELISA (detection limit: 15 nM) and in a lateral flow test system (detection limit: 3 ng), using gold nanoparticle conjugated- DAFC-bovine serum albumin for competition. Overall, this work reveals for the first time a recombinant TAFC-specific monoclonal antibody with diagnostic potential for IPA diagnosis in traditional and emerging patient groups (e.g., COVID-19) and presents a useful strategy for murine Ig sequence determination, and expression in HEK293 cells, to overcome unexpected limitations associated with aberrant or deficient murine monoclonal antibody production.

Silkworm recombinant bovine zona pellucida protein 4 (bZP4) as a potential female immunocontraceptive antigen; impaired sperm-oocyte interaction and ovarian dysfunction

Porcine zona pellucida proteins (ZPs) have been utilized as female immunocontraceptive antigens. The purpose of this study was to explore the potential use of silkworm recombinant bovine ZP4 as an alternative. When the protein was injected with monophosphoryl lipid A (MPL) - an immuno-stimulative agent - into two female goats, marked elevation of the anti-ZP4 titer was detected. Application of the purified specific IgG to a porcine in vitro fertilization system reduced the sperm penetration rate. In one goat, the cyclic profile of serum progesterone disappeared as the anti-ZP4 titer increased. Histological examination of the ovaries revealed degeneration of antral follicles with sparse infiltration of inflammatory cells in the theca, indicating that autoimmune oophoritis had been induced. Together, the present results suggest that recombinant ZP4 disturbs fertilization and exerts a pathogenic effect on follicle development in goats, thus indicating its potential as a female immunocontraceptive antigen.

An approach to chimeric subunit immunogen provides efficient protection against toxicity, type III and type v secretion systems of Shigella

OBJECTIVES

Shigellosis is one of the infectious diseases causing severe intestinal illness in human beings. Development of an effective vaccine against Shigella is a key to deal with this bacterium. The present study aimed at evaluation of the antibody response as well as the protection of the recombinant chimeric protein containing IpaD, IpaB, StxB, and VirG against Shigella dysentery and flexneri.

METHODS

Chimeric protein was expressed and purified by Ni-NTA resin. The identity of the protein was determined by Western blot analysis. Mouse groups were immunized with the recombinant protein and the humoral immune response was measured by Enzyme-Linked Immunosorbent Assay (ELISA). Additionally, neutralization of the bacterial toxin by antibody was assessed by MTT assay. Animal challenge against S.dysentery and S. flexneri was evaluated, as well.

RESULTS

Protein expression and purification were confirmed by SDS-PAGE and western blotting. Analysis of the immune responses demonstrated that the antibody responses were higher in the sera of the subcutaneously immunized mice compared to those immunized intraperitoneally. In vitro neutralization analysis indicated that the 1:10000 dilution of the sera had a high ability to neutralize 0.25 ng/µl (CD50) of the toxin on the Vero cell line. Furthermore, the results of the animal challenge showed that the immunized mice were completely protected against 50 LD50 of the bacterial toxin. Immunization also protected 80% of the mice from 10 LD₅₀ by S. flexneri and S.dysentery. In addition, passive immunization conferred 60% protection in the mice against S. flexneri and S.dysentery. Organ burden studies also revealed a significant reduction in infection among the immunized mice.

CONCLUSION

This study revealed that the chimeric protein produced inE. colicould be a promising chimeric immunogen candidate against Shigella.

Neutralization of crotamine by polyclonal antibodies generated against two whole rattlesnake venoms and a novel recombinant fusion protein

Crotamine is a paralyzing toxin (MW: ~5 kDa) found in different proportions in some rattlesnake venoms (up to 62%). Mexican pit viper antivenoms have shown low immunoreactivity against crotamine, which is an urgent quality to be improved. The objective of this work was to evaluate the ability of a novel recombinant fusion protein composed of sphingomyelinase D and crotamine, and two whole venoms from Crotalus molossus nigrescens and C. oreganus helleri to produce neutralizing antibodies against crotamine. These immunogens were separately used for immunization procedures in rabbits. Then, we generated three experimental antivenoms to test their cross-reactivity via western-blot against crotamine from 7 species (C. m. nigrescens, C. o. helleri, C. durissus terrificus, C. scutulatus salvini, C. basiliscus, C. culminatus and C. tzabcan). We also performed pre-incubation neutralization experiments in mice to measure the neutralizing potency of each antivenom against crotamine induced hind limb paralysis. Our antivenoms showed broad recognition across crotamine from most of the tested species. Also, neutralization against crotamine paralysis symptom was successfully achieved by our three antivenoms, albeit with different efficiencies. Our results highlight the use of crotamine enriched venoms and our novel recombinant fusion protein as promising immunogens to improve the neutralizing potency against crotamine for the improvement of Mexican antivenoms.

Gamma irradiated protease from Echis pyramidum venom: A promising immunogen to improve viper bites treatment

Echis pyramidum (Epy) is a venomous snake belongs to Viperidae family; it causes fetal coagulopathy systemic effects and death. Searching for more effective and safe antivenom is mandatory for viper bites treatment. Proteases are the most lethal components in viper venom inducing hemorrhage, edema and coagulation problems. Thus, the study aims to evaluate the potency of the prepared antisera and their neutralizing properties against the biological activities induced by whole Epy venom individually. Echis pyramidum metalloprotease enzyme (60 kDa) was purified using size-exclusion followed by DEAE-ion exchange chromatography. The purified Epy metalloprotease enzyme (SVMP) was detoxified with 1.5 kGy gamma rays from cobalt⁶⁰ gamma cell and used for immunization. 1.5 kGy irradiated Epy metalloprotease (SVMPi) showed less lethal activity (LD₅₀) compared to the corresponding native immunogen. The prepared antisera boosted against whole Epy venom (WV), 1.5 kGy irradiated whole Epy venom (WVi), SVMP and SVMPi were tested for neutralization of lethality and biological activities induced by Epy venom. The antibodies elicited against WVi and SVMPi were 30,000 and 20,000 EU, respectively. The anti-SVMPi serum showed the highest neutralization of lethality (ED₅₀) compared to the other prepared antisera. In addition, it prolonged the clotting time from 49.0 ± 2.5 to 176.2 ± 1.4 s. Furthermore, it demonstrated a highly neutralizing activity against edema induction and hemorrhage of Epy venom by 66.8% and 94.3%, respectively compared with the other prepared antisera. These findings would encourage further studies for using gamma irradiated purified fraction(s) from different snake venoms as safe antigen(s) to produce more effective antivenoms.

Neutralizing potency and immunochemical evaluation of an anti-Crotalus mictlantecuhtli experimental serum

Snakebite in Mexico is commonly treated with an antivenom which uses Bothrops asper and Crotalus simus venoms as immunogens. Current taxonomic recommendations for the C. simus species complex suggest a novel endemic species from Mexico: Crotalus mictlantecuhtli. The aim of this report was to evaluate the immunogenic properties of C. mictlantecuhtli venom and its potential to generate polyclonal antibodies capable of neutralizing other pitviper venoms. We generated an experimental anti-Crotalus mictlantecuhtli serum, using the rabbit model, to test recognition and neutralizing capacity against the homologous venom as well as venoms from C. atrox, C.basiliscus, C. durissus terrificus, C. scutulatus salvini, C. tzabcan and Ophryacus sphenophrys. Pre-incubation neutralization experiments using our experimental serum showed positive results against venoms containing crotoxin, while venoms from two non-neurotoxic pit-vipers were not neutralized. Rescue experiments in mice showed that, when intravenously injected (i.v.), C. mictlantecuhtli venom is not neutralized by a maximum dose of Antivipmyn® and the experimental serum after 5 min of envenomation, albeit mice envenomated intraperitoneally (i.p.) and rescued i.v. with Antivipmyn® survived even at 50 min after envenomation. Our results highlight the importance of using the highly neurotoxic C. mictlantecuhtli venom to increase antivenom effectiveness against Mexican neurotoxic pitvipers.

Identification of a novel protective antigen, 3-oxoacyl-[acyl-carrier-protein] synthase II of Streptococcus equi ssp. zooepidemicus which confers protective effects

Streptococcus equi ssp. zooepidemicus (SEZ) is an important swine pathogen and responsible for a wide variety of infections in many animal species. FabF was a novel protein identified in the previous study. However, its protective efficacy remained to be evaluated. In this study, recombinant fabF of SEZ was expressed and showed a strong immunoreactivity with mini-pig convalescent sera. Study in mice revealed that the recombinant protein induced a marked antibody response and protected 80% of mice against SEZ infection. The hyperimmune sera against fabF could efficiently kill the bacteria in the phagocytosis test. In addition, it was also found that anti- fabF antibodies can significantly inhibit the formation of SEZ biofilm. These study suggest that fabF may represent immunogens of interest for vaccine development against SEZ infection.

Bovine immunisation with a recombinant peptide derived from synthetic SBm7462® (Bm86 epitope construct) immunogen for Rhipicephalus microplus control

RHIPICEPHALUS MICROPLUS: is the most important ectoparasite of livestock in tropical and subtropical areas around the world. Research focused on developing an efficient vaccine for cattle tick control is a high priority. The aim of this study was to evaluate the rSBm7462® peptide (Bm86-B and T cell epitopes) regarding its properties of immunogenicity, protective effect in cattle and efficacy against R. microplus. This peptide was produced by a fermentative process in the yeast culture system of Komagataella (Pichia) pastoris strain Km 71. The vaccination assay was conducted in a tick-free area using non-splenectomised Holstein Friesian calves, separated into immunisation and control groups. These animals individually received the recombinant peptide and the inoculum without peptide using saponin as an adjuvant at three time points. The calves were challenged 21 days after the last immunisation using 4500 larvae per animal. An indirect ELISA was used to identify the IgG kinetics of serum samples from the calves studied. The qPCR was performed to determine the cytokine gene expression from the total RNA of the cultured PBMCs. Histomorphometry of the germinal centres (GCs) was performed measuring slides with haematoxylin-eosin staining of surgically removed lymph nodes from immunised calves. The antibody response showed a significant induction of high-affinity IgGs in calves immunised with the recombinant peptide in comparison to the controls. The kinetics of antibodies in immunised calves showed a significant increase during the experiment. This increase in high-affinity IgGs correlated with a gradual increase of the GC diameter following each peptide vaccination. Cytokine expression profiles demonstrating an adaptive immune response in calves immunised with rSBm7462® confirmed the T-dependent response. Vaccine efficacy was calculated at 72.4 % following the analysis and fecundity of collected adult female ticks, compared between control and vaccinated groups. These findings demonstrate that this new recombinant peptide is an option for control of R. microplus infestations.

One-step sequence and structure-guided optimization of HIV-1 envelope gp140

Stabilization of the metastable envelope glycoprotein (Env) of HIV-1 is hypothesized to improve induction of broadly neutralizing antibodies. We improved the expression yield and stability of the HIV-1 envelope glycoprotein BG505SOSIP.664 gp140 by means of a previously described automated sequence and structure-guided computational thermostabilization approach, PROSS. This combines sequence conservation information with computational assessment of mutant stabilization, thus taking advantage of the extensive natural sequence variation present in HIV-1 Env. PROSS is used to design three gp140 variants with 17–45 mutations relative to the parental construct. One of the designs is experimentally observed to have a fourfold improvement in yield and a 4 °C increment in thermostability. In addition, the designed immunogens have similar antigenicity profiles to the native flexible linker version of wild type, BG505SOSIP.664 gp140 (NFL Wt) to major epitopes targeted by broadly neutralizing antibodies. PROSS eliminates the laborious process of screening many variants for stability and functionality, providing a proof of principle of the method for stabilization and improvement of yield without compromising antigenicity for next generation complex, highly glycosylated vaccine candidates.

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One-step stabilization of HIV-1 Env gp140.

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One-step yield improvement of HIV-1 Env gp140.

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Native-like oligomeric conformation of designed vaccine candidates.

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Unaltered antigenicity of designed vaccine candidates.

Antibody Complexes

Monoclonal based therapeutics have always been looked at as a futuristic natural way we could take care of pathogens and many diseases. However, in order to develop, establish and realize monoclonal based therapy we need to understand how the immune system contains or kill pathogens. Antibody complexes serve the means to decode this black box. We have discussed examples of antibody complexes both at biochemical and structural levels to understand and appreciate how discoveries in the field of antibody complexes have started to decoded mechanism of viral invasion and create potential vaccine targets against many pathogens. Antibody complexes have made advancement in our knowledge about the molecular interaction between antibody and antigen. It has also led to identification of potent protective monoclonal antibodies. Further use of selective combination of monoclonal antibodies have provided improved protection against deadly diseases. The administration of newly designed and improved immunogen has been used as potential vaccine. Therefore, antibody complexes are important tools to develop new vaccine targets and design an improved combination of monoclonal antibodies for passive immunization or protection with very little or no side effects.

Intestinal changes and performance parameters in ticks feeding on calves immunized with subunits of immunogens against Rhipicephalus microplus

We describe the intestinal changes and biological parameters of the tick species Rhipicephalus microplus exposed to the immune response of calves vaccinated with two subunits of immunogens. The first group of Bos taurus calves was immunized with a synthetic peptide (SBm7462), whereas the second group received an inoculum for synthetic control. The third group was immunized with a recombinant peptide (rSBm7462); an inoculum was injected into a fourth group of calves for recombinant control. Each formulation was administered to these calves during three times at intervals of 30 days. At 21 days after the last immunization, the calves were challenged using a total of 4500 larvae per animal. Indirect ELISA was realized to identify the kinetics of IgGs from samples of calves studied. Naturally detaching ticks were collected for analyses of biological performance and histological changes in the midgut. We dissected randomly detached ticks. The midgut of each of these ticks was removed and processed routinely for histology, stained with hematoxylin-eosin (H&E) and slow Giemsa. Slides were also subjected to immunohistochemistry. The antibody response showed significant induction of high-affinity IgGs in calves immunized with both peptides in comparison to calves of the control groups. Histological changes included damage of the intestinal epithelium in ticks fed on immunized hosts and intense immunostaining in midgut cells, using the serum of calves immunized with recombinant peptide. There were significant differences in all biological performing parameters of ticks detached from vaccinated calves in comparison with ticks of the control groups. We identified reductions of 87.7 and 93.5% in engorged ticks detached from calves immunized with a synthetic and recombinant peptides, respectively, a 28 and 8.60% lower egg mass in groups immunized with synthetic and recombinant peptides, respectively, and a 38.4% reduction of the value of nutrient index/tick in the group immunized with the recombinant peptide. Our findings show that the immune response induced by small peptides in cattle can modify the digestion and metabolism of ticks fed on vaccinated animals, resulting in changes in tick performance.

Immunogenicity Evaluation of Recombinant Edible Vaccine Candidate Containing HER2-MUC1 against Breast Cancer

Human epithelial growth factor receptor2 (Her2) and polymorphic epithelial mucin (MUC1) are tumor-associated antigens that have been extensively investigated in adenocarcinomas. Generally, each of these molecules was used separately for diagnosis of adenocarcinomas and as an injective vaccines in cancer therapy researches, but not in the chimeric form as an edible immunogen. In this study, Her2, MUC1, and a novel fusion structure were expressed in the seeds and hairy roots of transgenic plants appropriately. The mice groups were immunized either by feeding of transgenic seeds or hairy roots. All immunized groups showed a considerable rise in anti-glycoprotein serum IgG and IgA, and IFNɣ cytokine. However, the animals received chimeric protein showed significant higher immune responses in comparison to ones received one of these immunogen. The results indicated that the oral immunization of an animal model with transgenic plants could effectively elicit immune responses against two major tumor-associated antigens.

Design of immunogens: The effect of bifunctional chelator on immunological response to chelated copper

To produce specific antibodies for the detection and quantification of copper ions, bifunctional chelators (BFCs) are commonly applied in the preparation of copper conjugates. However, some copper-chelator complexes exhibit limited stability under in vivo conditions. In this study, Cu²⁺ was coupled with carrier proteins via three different macrocyclic BFCs: p-SCN-Bn-DOTA, p-SCN-Bn-NOTA, and p-SCN-Bn-TETA. The stability in plasma and the immunogenicity of three copper immunoconjugates were compared. The chelators other than p-SCN-Bn-DOTA were very stable in plasma, with <9% dissociation of Cu²⁺ over 96 h. The immune response varied depending on the choice of chelator; notably, antisera from the Cu²⁺-NOTA-KLH conjugate demonstrated the best reactivity toward chelated Cu²⁺. p-SCN-Bn-NOTA, which showed significant advantages over the other chelators, was used for antibody production. The efficiency of immune-positive hybridoma production was satisfactory, and the resultant monoclonal antibodies (McAbs) 4B7 showed sensitivity (half-maximal inhibitory concentration (IC₅₀) of 8.9 ng/mL) to chelated Cu²⁺, with a working range from 1.21 to 48.9 ng/mL. The recovery of Cu²⁺ from water samples was 85.7-108%, and the intra- and inter-assay coefficients of variation were 4.0-10.1% and 7.1-11.4%, respectively. Compared with previously reported McAb specific to Cu²⁺, DF4, the sensitivity of the newly developed assay was improved 100-fold. The results of this study indicate the utility of NOTA for the efficient generation of highly sensitive McAbs against Cu²⁺.

Functional and immunogenic characterization of diverse HCV glycoprotein E2 variants

BACKGROUND & AIMS

Induction of cross-reactive antibodies targeting conserved epitopes of the envelope proteins E1E2 is a key requirement for an hepatitis C virus vaccine. Conserved epitopes like the viral CD81-binding site are targeted by rare broadly neutralizing antibodies. However, these viral segments are occluded by variable regions and glycans. We aimed to identify antigens exposing conserved epitopes and to characterize their immunogenicity.

METHODS

We created hepatitis C virus variants with mutated glycosylation sites and/or hypervariable region 1 (HVR1). Exposure of the CD81 binding site and conserved epitopes was quantified by soluble CD81 and antibody interaction and neutralization assays. E2 or E1-E2 heterodimers with mutations causing epitope exposure were used to immunize mice. Vaccine-induced antibodies were examined and compared with patient-derived antibodies.

RESULTS

Mutant viruses bound soluble CD81 and antibodies targeting the CD81 binding site with enhanced efficacy. Mice immunized with E2 or E1E2 heterodimers incorporating these modifications mounted strong, cross-binding, and non-interfering antibodies. E2-induced antibodies neutralized the autologous virus but they were not cross-neutralizing.

CONCLUSIONS

Viruses lacking the HVR1 and selected glycosylation sites expose the CD81 binding site and cross-neutralization antibody epitopes. Recombinant E2 proteins carrying these modifications induce strong cross-binding but not cross-neutralizing antibodies.

LAY SUMMARY

Conserved viral epitopes can be made considerably more accessible for binding of potently neutralizing antibodies by deletion of hypervariable region 1 and selected glycosylation sites. Recombinant E2 proteins carrying these mutations are unable to elicit cross-neutralizing antibodies suggesting that exposure of conserved epitopes is not sufficient to focus antibody responses on production of cross-neutralizing antibodies.

Immunological responsiveness of intestinal tissue explants and mucosal mononuclear cells to ex vivo stimulation

BACKGROUND

There are limited data on the immunological responsiveness of healthy intestinal tissue when it is cultured and stimulated ex vivo. Such an ex vivo model has the potential to be a valuable tool in understanding disease pathogenesis and as a preclinical tool for the assessment of candidate therapeutic agents used to treat inflammatory bowel disease (IBD).

AIM

We undertook a comprehensive study to evaluate ex vivo immunological responses of intestinal tissue and isolated mucosal mononuclear cells (MMC) to a broad range of stimuli.

METHODS

Colorectal biopsies (explants) were obtained from healthy participants by flexible sigmoidoscopy and were placed either directly into culture or digested to isolate MMC prior to placement in culture. Explants or MMC were treated with polyinosinic:polycytidylic acid (Poly IC), phytohemagglutinin (PHA), lipopolysacccharides from E Coli (LPS), anti-CD3/CD28 antibodies, or IL-1β/TNF-α for 24 h. Supernatants were assayed for 40 inflammatory biomarkers using multiplexed enzyme-linked immunosorbent assay (ELISA). The isolated MMCs were further characterized using twelve color flow cytometry.

RESULTS

Explants have greater weight adjusted constitutive expression of inflammatory biomarkers than MMCs. Biomarker responses varied as a function of immunogen and use of intact tissue or isolated cells. PHA applied to intact explants was the most effective agent in inducing biomarker changes. Stimulation induced activated and memory cellular phenotypes in both explants and MMCs.

CONCLUSIONS

The breadth and magnitude of responses from intact and enzymatically digested intestinal tissue explants stimulated with exogenous immunogens are complex and vary by tissue form and treatment. Overall, PHA stimulation of intact explants produced the most robust responses in normal human colorectal tissue. This system could potentially serve as a preliminary model of the disease state, suitable for small scale screening of new therapeutic agents prior to using IBD patient derived tissue.

In silico-guided sequence modifications of K-ras epitopes improve immunological outcome against G12V and G13D mutant KRAS antigens

Background

Somatic point substitution mutations in the KRAS proto-oncogene primarily affect codons 12/13 where glycine is converted into other amino acids, and are highly prevalent in pancreatic, colorectal, and non-small cell lung cancers. These cohorts are non-responsive to anti-EGFR treatments, and are left with non-specific chemotherapy regimens as their sole treatment options. In the past, the development of peptide vaccines for cancer treatment was reported to have poor AT properties when inducing immune responses. Utilization of bioinformatics tools have since become an interesting approach in improving the design of peptide vaccines based on T- and B-cell epitope predictions.

Methods

In this study, the region spanning exon 2 from the 4th to 18th codon within the peptide sequence of wtKRAS was chosen for sequence manipulation. Mutated G12V and G13D K-ras controls were generated in silico, along with additional single amino acid substitutions flanking the original codon 12/13 mutations. IEDB was used for assessing human and mouse MHC class I/II epitope predictions, as well as linear B-cell epitopes predictions, while RNA secondary structure prediction was performed via CENTROIDFOLD. A scoring and ranking system was established in order to shortlist top mimotopes whereby normalized and reducing weighted scores were assigned to peptide sequences based on seven immunological parameters. Among the top 20 ranked peptide sequences, peptides of three mimotopes were synthesized and subjected to in vitro and in vivo immunoassays. Mice PBMCs were treated in vitro and subjected to cytokine assessment using CBA assay. Thereafter, mice were immunized and sera were subjected to IgG-based ELISA.

Results

In silico immunogenicity prediction using IEDB tools shortlisted one G12V mimotope (68-V) and two G13D mimotopes (164-D, 224-D) from a total of 1,680 candidates. Shortlisted mimotopes were predicted to promote high MHC-II and -I affinities with optimized B-cell epitopes. CBA assay indicated that: 224-D induced secretions of IL-4, IL-5, IL-10, IL-12p70, and IL-21; 164-D triggered IL-10 and TNF-α; while 68-V showed no immunological responses. Specific-IgG sera titers against mutated K-ras antigens from 164-D immunized Balb/c mice were also elevated post first and second boosters compared to wild-type and G12/G13 controls.

Discussion

In silico-guided predictions of mutated K-ras T- and B-cell epitopes were successful in identifying two immunogens with high predictive scores, Th-bias cytokine induction and IgG-specific stimulation. Developments of such immunogens are potentially useful for future immunotherapeutic and diagnostic applications against KRAS(+) malignancies, monoclonal antibody production, and various other research and development initiatives.

Dietary Immunogen® modulated digestive enzyme activity and immune gene expression in Litopenaeus vannamei post larvae

Pacific white shrimp Litopenaeus vannamei (Boone, 1931) is an important economical shrimp species worldwide, especially in the Middle East region, and farming activities of this species have been largely affected by diseases, mostly viral and bacterial diseases. Scientists have started to use prebiotics for bolstering the immune status of the animal. This study aimed to investigate the influence of Immunogen^® on growth, digestive enzyme activity and immune related gene expression of Litopenaeus vannamei post-larvae. All post-larvae were acclimated to the laboratory condition for 14 days. Upon acclimation, shrimps were fed on different levels of Immunogen^® (0, 0.5, 1 and 1.5 g kg^-1) for 60 days. No significant differences were detected in weight gain, specific growth rate (SGR) and food conversion ratio (FCR) in shrimp post-larvae in which fed with different levels of Immunogen^® and control diet. The results showed that digestive enzymes activity including protease and lipase increased with different amounts of Immunogen^® in the shrimp diet. Protease activity increased with 1.5 g kg^-1 Immunogen^® after 60 days and lipase activity increased with 1 and 1.5 g kg^-1 Immunogen^® after 30 and 60 days of the trial respectively (P < 0.05), while amylase activity did not change in response to different levels of Immunogen^® (P > 0.05). The expression of immune related genes including, prophenoloxidase, crustin and g-type lysozyme increased with diet 1.5 g kg^-1 Immunogen^® (P < 0.05) while expression of penaeidin gene increased only with experimental diet 1 g kg^-1 of Immunogen^®. These results indicated that increase in digestive enzymes activity and expression of immune related genes could modulate the Immunogen^® in the innate immune system in L. vannamei in this study.

Glycine Substitution at Helix-to-Coil Transitions Facilitates the Structural Determination of a Stabilized Subtype C HIV Envelope Glycoprotein

Advances in HIV-1 envelope glycoprotein (Env) design generate native-like trimers and high-resolution clade A, B, and G structures and elicit neutralizing antibodies. However, a high-resolution clade C structure is critical, as this subtype accounts for the majority of HIV infections worldwide, but well-ordered clade C Env trimers are more challenging to produce due to their instability. Based on targeted glycine substitutions in the Env fusion machinery, we defined a general approach that disfavors helical transitions leading to post-fusion conformations, thereby favoring the pre-fusion state. We generated a stabilized, soluble clade C Env (16055 NFL) and determined its crystal structure at 3.9 Å. Its overall conformation is similar to SOSIP.664 and native Env trimers but includes a covalent linker between gp120 and gp41, an engineered 201-433 disulfide bond, and density corresponding to 22 N-glycans. Env-structure-guided design strategies resulted in multiple homogeneous cross-clade immunogens with the potential to advance HIV vaccine development.

[Inflammatory diseases of the thyroid gland]

This review article deals with the classification, clinical features and morphology of thyroiditis. These inflammatory diseases account for approximately 20 % of all thyroid diseases. The vast majority of cases of thyroiditis are of immunogenic origin while non-immunogenic thyroiditis (caused by pathogens or iatrogenic) is a rarity.

Design and expression of recombinant toxins from Mexican scorpions of the genus Centruroides for production of antivenoms

This manuscript describes the design of plasmids containing the genes coding for four main mammalian toxins of scorpions from the genus Centruroides (C.) of Mexico. The genes that code for toxin 2 of C. noxius (Cn2), toxin 2 from C. suffusus (Css2) and toxins 1 and 2 from C. limpidus (Cll1 and Cll2) were included into individual plasmids carrying the genetic construction for expression of fusion proteins containing a leader peptide (pelB) that directs the expressed protein to the bacterial periplasm, a carrier protein (thioredoxin), the cleavage site for enterokinase, the chosen toxin and a poly-histidine tag (6xHis-tag) for purification of the hybrid protein by immobilized metal ion affinity chromatography after expression in Escherichia coli strain BL21 (DE3). The purified hybrid proteins containing the recombinant toxins (abbreviated Thio-EK-Toxin) were used for immunization of three independent groups of ten mice and four rabbits. Challenging the first group of mice, immunized with recombinant Thio-EK-Css2, with three median lethal doses (LD₅₀) of C. suffusus soluble venom resulted in the survival of all the test animals without showing intoxication symptoms. All control mice (none immunized) died. Similar results were obtained with mice previously immunized with Thio-EK-Cn2 and challenged with C. noxius venom. The third group of mice immunized with both Thio-EK-Cll1 and Thio-EK-Cll2 showed an 80% survival ratio when challenged with only one LD₅₀ of C. limpidus venom, all showing symptoms of intoxication. The sera from rabbits immunized with a combination of the four recombinant toxins were collected separately and used to assess their neutralization capacity in vitro (pre-incubating the serum with the respective scorpion venom and injecting the mixture into mice), using six mice for each serum/venom combination tested. The venoms from the six most dangerous scorpion species of Mexico were assayed: C. noxius, C. suffusus, C. limpidus, C. elegans, C. tecomanus and C. sculpturatus. Two hundred and 50 μL of serum from any of the immunized rabbits were enough to neutralize three LD₅₀ of any of the tested venoms, with mice showing no symptoms of intoxication. These results confirm that the recombinant forms of the main toxins from the most dangerous scorpions of Mexico are excellent immunogens for the production of antivenoms to treat scorpion intoxications.

Adjuvant role of Pseudomonas flagellin for Acinetobacter baumannii biofilm associated protein

AIM

To study immunogenicity of Pseudomonas N terminal flagellin as an adjuvant for Acinetobacter baumannii (A. baumannii) biofilm associated protein (Bap).

METHODS

The N terminal flagellin gene was amplified. The pET28a (+) and polymerase chain reaction products were digested with HindIII and EcoR I. The ligation of N terminal flagellin into pET28a (‏+) was performed using T4 DNA ligase and was then transformed into Escherichia coli BL21 (DE3) as a suitable expression host. pET28a (‏+) vector harboring a conserved region of Bap from our previous work was used. The recombinant proteins were expressed, analyzed by SDS-PAGE method and was purified by affinity chromatography with His-Tag residues followed by confirmation with western blotting. Mice were immunized with recombinant N terminal flagellin and Bap subunits. The immunized animals were intranasally (i.n) challenged with A. baumannii and Pseudomonas aeruginosa (P. aeruginosa).

RESULTS

The flagellin enhanced the immunogenicity of Bap causing an increase in specific IgG titers in serum (P < 0.001). Internal organs, i.e., liver, lung and spleen of the Bap-Flagellin immunized group challenged with A. baumannii showed significantly lower bacterial load compared to the control group. The bacterial loads were studied in internal organs. A. baumannii infected immunized animals with Bap-Flagellin exhibited internal organs with minor bacterial load while P. aeruginosa PAO1 infected group showed heavy bacterial load of (4.3 ± 0.12) × 10⁶, (1.1 ± 0.01) × 10⁶ and (2.2 ± 0.22) × 10⁶ per gram of lungs, liver and spleen respectively. Bacterial loads were detected per gram of lungs, liver and spleen of the mice group immunized with Bap were (1.2 ± 0.06) × 10⁷, (11.1 ± 0.041) × 10⁵ and (3.6 ± 0.42) × 10⁶ respectively. In vivo neutralization assay indicated that all experimental mice groups, except for Flagellin administered group was significantly (P < 0.05) protected against A. baumannii.

CONCLUSION

These results demonstrate that P. aeruginosa Flagellin as an adjuvant for Bap_{A. baumannii} could be a useful model to evaluate new vaccine against A. baumannii.

Protective effects of the prebiotic on the immunological indicators of rainbow trout (Oncorhynchus mykiss) infected with Aeromonas hydrophila

The aim of this study was to investigate the protective effects of dietary administration of commercial prebiotic, Immunogen, on immunological indicators, enzymatic responses and stress tolerance in juvenile (81.65 ± 1.49) rainbow trout (Oncorhynchus mykiss) following Aeromonas hydrophila infection. The first group of fish was fed with the diet containing 2 g kg(-1) Immunogen whilst the control group received the diet free of Immunogen. There were three replicates per group. After 6 weeks feeding, the control group were divided into two treatments injected with saline buffer (control), and 1.5 × 10(8) CFU A. hydrophila respectively. The fish fed with the Immunogen supplemented diet were also injected with 1.5 × 10(8) CFU A. hydrophila. Our results revealed that dietary Immunogen increased the level of white blood cell (WBC) and percentage of lymphocyte (P < 0.05), however, the level of red blood cell (RBC), Hematocrit (Hct), hemoglobin (Hb) and percent of monocyte decreased in Untreated-Challenged group but unaffected in the group fed with Immunogen (P < 0.05). The level of lysozyme, alternative complement, antiprotease activity, total protein, albumin and globulin decreased in Untreated- Challenged group compared to control group. However, there was an increase in the level of lysozyme, alternative complement, antiprotease activity, bactericidal activity, in the Treated- Challenged group compared to other groups (P < 0.05). Serum alkali phosphatase (ALT) and aspartate aminotransferase, significantly increased fallowing challenge with A. hydrophila but in the Treated-Challenged group, there was no significant difference compared to the control group (P < 0.05). Lactate dehydrogenase (LDH) level was not different between groups (P > 0.05). Serum cortisol and glucose levels were higher in the challenge group, but these levels were lower in fish under challenge that were fed Immunogen-supplemented diet in contrast to the group fed control diet. The stress responses affected by A. hydrophila challenge (P < 0.05). Serum sodium, potassium and calcium concentration decreased by A. hydrophila exposure (P < 0.05), and Immunogen showed protection effect against this change.

Anti-miroestrol polyclonal antibodies: a comparison of immunogen preparations used to obtain desired antibody properties

Immunogen quality is one important factor that contributes to desirable antibody characteristics. Highly specific antibodies against miroestrol can be used to develop a quality control immunoassay for Pueraria candollei products. In this study, we investigated how various immunogen preparations affect antibody properties. The results show that immunogen prepared using the Mannich reaction provides antibodies with higher specificity and sensitivity against miroestrol than immunogen prepared with the periodate reaction. The results suggest the Mannich reaction maintains the original structure of miroestrol and generates useful antibodies for developing immunoassays.

New directions in nicotine vaccine design and use

Clinical trials of nicotine vaccines suggest that they can enhance smoking cessation rates but do not reliably produce the consistently high serum antibody concentrations required. A wide array of next-generation strategies are being evaluated to enhance vaccine efficacy or provide antibody through other mechanisms. Protein conjugate vaccines may be improved by modifications of hapten or linker design or by optimizing hapten density. Conjugating hapten to viruslike particles or disrupted virus may allow exploitation of naturally occurring viral features associated with high immunogenicity. Conjugates that utilize different linker positions on nicotine can function as independent immunogens, so that using them in combination generates higher antibody concentrations than can be produced by a single immunogen. Nanoparticle vaccines, consisting of hapten, T cell help peptides, and adjuvants attached to a liposome or synthetic scaffold, are in the early stages of development. Nanoparticle vaccines offer the possibility of obtaining precise and consistent control of vaccine component stoichiometry and spacing and immunogen size and shape. Passive transfer of nicotine-specific monoclonal antibodies offers a greater control of antibody dose, the ability to give very high doses, and an immediate onset of action but is expensive and has a shorter duration of action than vaccines. Viral vector-mediated transfer of genes for antibody production can elicit high levels of antibody expression in animals and may present an alternative to vaccination or passive immunization if the long-term safety of this approach is confirmed. Next-generation immunotherapies are likely to be substantially more effective than first-generation vaccines.

Impact of the Immunogen Nature on the Immune Response against the Major HBV Antigens in an HBsAg and HLA-humanized Transgenic Mouse Model

Hepatitis B chronic carriage remains as a major public health problem. Protein and DNA vaccines are now widely used in therapeutic vaccine candidates. Although, the hepatitis B surface antigen (HBsAg) based vaccines have been largely studied, candidates comprising both HBsAg and core (HBcAg) either protein- or DNA-based approaches deserve further immunological characterization.

In the present study, a repeated dose administration schedule for protein or DNA immunogens was conducted in order to characterize the resulting immune response in a humanized and HBsAg-tolerized setting. A novel transgenic (Tg) mice that express the HBsAg, human MHC class I (HLA-A*0201) and MHC class II (HLA-DRB1*01) molecules and devoid of endogenous murine class I and II molecules was used as a model of HBV chronic carrier. Mice were immunized by subcutaneous (protein) or intramuscular (DNA) routes and the humoral and cellular responses were evaluated.

Protein or DNA immunization induced humoral immune responses against both HBsAg and HBcAg. The systematic analysis of epitopes that activate CD4+ and CD8+ T lymphocytes confirmed the accuracy of the model. Cellular immune responses were detected differing in their nature. CD8 T-cell responses were induced mostly after DNA immunization while CD4 T-cell responses were predominant in protein based immunizations. In addition, the intensity of HLA-A2-restricted CD8+ T cell responses was reduced in Tg mice expressing HBsAg when compared to control Tg mice.

In conclusion, our results indicate that cellular immune responses necessary for the development of protective immunity can be achieved by DNA or protein immunization. However, important differences in their nature arise when immunogens are administered several times.

How to cite this article: Mancini-Bourgine M, Guillen G, Michel ML, Aguilar JC. Impact of the Immunogen Nature on the Immune Response against the Major HBV Antigens in an HBsAg and HLA-humanized Transgenic Mouse Model. Euroasian J Hepato-Gastroenterol 2014;4(1):36-44.

Increased efficacy of a trivalent nicotine vaccine compared to a dose-matched monovalent vaccine when formulated with alum

Vaccination against nicotine is a potential treatment for tobacco smoking. Clinical trials show effect only in high antibody responders; therefore it is necessary to increase the effectiveness of nicotine vaccines. The use of a multivalent vaccine that activates several B cell populations is a possible approach to increase antibody response. The aim of this study was to investigate whether three different nicotine immunogens could be mixed to generate independent responses resulting in additive antibody titers, and whether this would alter nicotine distribution to a greater extent than antibodies generated by a monovalent vaccine. When immunogens were administered s.c. with alum adjuvant, the trivalent vaccine generated significantly higher titers and prevented the distribution of an i.v. nicotine dose to brain to a greater extent than an equivalent dose of a monovalent vaccine. The number of rats with antibody titers >1:10,000 was significantly increased in the trivalent group compared to the monovalent group. There were no correlations between the titers generated by the different nicotine immunogens in the trivalent vaccine, supporting the hypothesis that the immunogens generated independent responses from distinct populations of B cells. In contrast, when administered i.p. in Freund's adjuvant, the trivalent nicotine vaccine was not more immunogenic than its component monovalent vaccine. Vaccine immunogenicity was suppressed if unconjugated protein was added to the monovalent vaccine formulated in Freund's adjuvant, compared to monovalent vaccine alone. These data suggest a protein-protein interaction that affects titers negatively and is apparent when the vaccines are formulated with Freund's adjuvant. In summary, a trivalent nicotine vaccine formulated with alum showed significantly higher efficacy than a dose-matched monovalent vaccine and may offer a strategy for increasing nicotine vaccine immunogenicity. This approach may be generalizable to other nicotine immunogens or vaccines for other addictive drugs.