Oral Administration of a Shigella 2aT32-Based Vaccine Expressing UreB-HspA Fusion Antigen With and Without Parenteral rUreB-HspA Boost Confers Protection Against Helicobacter pylori in Mice Model

Helicobacter pylori (H. pylori) is a gram-negative pathogen classified as a class I carcinogen. The H. pylori urease B subunit (UreB) and heat shock protein A (HspA) are two important vaccine candidate antigens. In this study, we evaluated the immunogenicity and immunoprotective effect of the attenuated Shigella vector vaccine SH02 expressing the UreB-HspA fusion protein of H. pylori in a mouse model. Oral SH02 with or without subcutaneous injection of rUreB-HspA induced antigen-specific serum IgG, mucosal sIgA, and T cells immune response. Subcutaneous injection of the candidate antigen rUreB-HspA enhanced the level of serum antigen-specific IgG antibodies (p < 0.0001) and the levels of IgG1/IgG2a/IgG2b subtypes. In addition, injection boost also increased the proportion of spleen antigen-specific CD4+CD154+ T cells (p < 0.001), and the proportion of CD4+CD154+ T cells that secrete IFN-γ and IL-17A. Following the H. pylori challenge, the levels of H. pylori colonization in the two experimental groups (Groups A and B) significantly reduced compared with the control group (p < 0.001), indicating that the candidate vaccine yielded a preventive effect of anti-H.pylori infection. Compared with the non-subcutaneous booster injection group (Group A), the subcutaneous booster injection group (Group B) exhibited less gastric inflammation, but there was no significant difference in the level of colonization (p > 0.05). These results lay a foundation for the development of a vaccine against H. pylori and the optimization of immunization methods and procedures to prevent H. pylori infection.

Evaluation of a multi-species Protein A-ELISA assay for plague serologic diagnosis in humans and other mammal hosts

Background

The Hemagglutination assay (HA) is widely used in plague diagnosis, however, it has a subjective interpretation and demands high amounts of antigen and other immunobiological supplies. On the other hand, the conventional Anti-IgG ELISA is limited by the need of specific conjugates for multiple plague hosts, which leaves a gap for new diagnostic methods able to cover both the diagnosis of human cases and the epidemiological surveillance of multiple sentinel species.

Methods

We developed an ELISA Protein A-peroxidase method to detect anti-F1 antibodies across several species, including humans. To determine the cut-off and performance rates, HA results from 288 samples (81 rabbits, 64 humans, 66 rodents and 77 dogs) were used as reference. Next, we evaluated the agreement between Protein A-ELISA and Anti-IgG ELISA in an expanded sample set (n = 487).

Results

Optimal conditions were found with 250ng/well of F1 and 1:500 serum dilution. Protein A-ELISA showed high repeatability and reproducibility. We observed good correlation rates between the Protein A and IgG ELISAs optical densities and a higher positive/negative OD ratio for the Protein A-ELISA method. The overall sensitivity, specificity and area under the curve for Protein A-ELISA were 94%, 99% and 0.99, respectively. Similar results were observed for each species separately. In the analysis of the expanded sample set, there was a strong agreement between Protein A and IgG assays (kappa = 0.97). Furthermore, there was no cross-reaction with other common infectious diseases, such as dengue, Zika, Chagas disease, tuberculosis (humans) and ehrlichiosis, anaplasmosis and leishmaniasis (dogs).

Conclusions

Altogether, the Protein A-ELISA showed high performance when compared both to HA and Anti-IgG ELISA, with a polyvalent single protocol that requires reduced amounts of antigen and can be employed to any plague hosts.

Here, we developed and evaluated an ELISA diagnostic test based on the Protein A-peroxidase conjugate that allows the test to be used for plague laboratorial diagnosis not only in humans, but also in a wide range of mammalian species. This particularity is specifically important for plague epidemiological surveillance, given that Yersinia pestis, the causative agent of plague, have a long list of animal reservoirs across distinct ecosystems. Briefly, we first evaluated the best reaction parameters, such as antigen concentration, serum and protein A-conjugate dilutions. Next, we used serum samples from humans, dogs, rodents and rabbits (n = 288) with known results for plague serology by a conventional method, to evaluate the performance of the new Protein A-ELISA test. We observed a good performance of the novel Protein A-ELISA test, with high sensitivity and specificity rates. Evaluation of the coefficient of variation revealed that the test measurements suffer little variation, and therefore, has high repeatability and reproducibility. Next, by evaluating 487 samples, we observed a high degree of concordance between the Protein A-ELISA with a conventional IgG-based ELISA. Furthermore, this test showed no significant cross-reaction with other common infectious diseases. Altogether, the Protein A-ELISA showed high performance when compared both to HA and Anti-IgG ELISA, with a single protocol that requires reduced amounts of antigen and can be employed to several plague hosts.

Functionalisation of Inorganic Material Surfaces with Staphylococcus Protein A: A Molecular Dynamics Study

Staphylococcus protein A (SpA) is found in the cell wall of Staphylococcus aureus bacteria. Its ability to bind to the constant Fc regions of antibodies means it is useful for antibody extraction, and further integration with inorganic materials can lead to the development of diagnostics and therapeutics. We have investigated the adsorption of SpA on inorganic surface models such as experimentally relevant negatively charged silica, as well as positively charged and neutral surfaces, by use of fully atomistic molecular dynamics simulations. We have found that SpA, which is itself negatively charged at pH7, is able to adsorb on all our surface models. However, adsorption on charged surfaces is more specific in terms of protein orientation compared to a neutral Au (111) surface, while the protein structure is generally well maintained in all cases. The results indicate that SpA adsorption is optimal on the siloxide-rich silica surface, which is negative at pH7 since this keeps the Fc binding regions free to interact with other species in solution. Due to the dominant role of electrostatics, the results are transferable to other inorganic materials and pave the way for new diagnostic and therapeutic designs where SpA might be used to conjugate antibodies to nanoparticles.

Induction of IDO1 and Kynurenine by Serine Proteases Subtilisin, Prostate Specific Antigen, CD26 and HtrA: A New Form of Immunosuppression?

Several serine proteases have been linked to autoimmune disorders and tumour initiation although the mechanisms are not fully understood. Activation of the kynurenine pathway enzyme indoleamine-2,3-dioxygenase (IDO1) modulates cellular activity in the brain, tolerogenesis in the immune system and is a major checkpoint in cancer development. We now report that IDO1 mRNA and IDO1 protein expression (generating kynurenine) are induced in human monocyte-derived macrophages by several chymotryptic serine proteases with direct links to tumorigenesis, including Prostate Specific Antigen (PSA), CD26 (Dipeptidyl-peptidase-4, CD26/DPP-4), High Temperature Requirement protein-A (HtrA), and the bacterial virulence factor subtilisin. These proteases also induce expression of the pro-inflammatory cytokine genes IL1B and IL6. Other serine proteases tested: bacterial glu-C endopeptidase and mammalian Pro-protein Convertase Subtilase-Kexin-3 (PCSK3, furin), urokinase plasminogen activator (uPA), cathepsin G or neutrophil elastase, did not induce IDO1, indicating that the reported effects are not a general property of all serine proteases. The results represent a novel mechanism of activating immunosuppressive IDO1 and inducing kynurenine generation which, together with the production of inflammatory cytokines, would contribute to tumour initiation and progression, providing a new target for drug development. In addition, the proteasomal S20 serine protease inhibitor carfilzomib, used in the treatment of myeloma, prevented the induction of IDO1 and cytokine gene expression, potentially contributing to its clinical anti-cancer activity.

Natural Human Immunity Against Staphylococcal Protein A Relies on Effector Functions Triggered by IgG3

Staphylococcal protein A (SpA) is a multifunctional, highly conserved virulence factor of Staphylococcus aureus. By binding the Fc portion of all human IgG subclasses apart from IgG3, SpA interferes with antibody and complement deposition on the bacterial surface, impairing staphylococcal clearance by phagocytosis. Because of its anti-opsonic properties, SpA is not investigated as a surface antigen to mediate bacterial phagocytosis. Herein we investigate human sera for the presence of SpA-opsonizing antibodies. The screening revealed that sera containing IgG3 against SpA were able to correctly opsonize the target and drive Fcγ receptor-mediated interactions and phagocytosis. We demonstrated that IgG3 Fc is significantly more efficient in inducing phagocytosis of SpA-expressing S. aureus as compared to IgG1 Fc in an assay resembling physiological conditions. Furthermore, we show that the capacity of SpA antibodies to induce phagocytosis depends on the specific epitope recognized by the IgGs on SpA molecules. Overall, our results suggest that anti-SpA IgG3 antibodies could favor the anti-staphylococcal response in humans, paving the way towards the identification of a correlate of protection against staphylococcal infections.

Preparation of Staphylococcal Protein A Imprinted Supermacroporous Cryogel Beads

Protein A is the most commonly used ligand in IgG purification due to its specific binding to the Fc receptor of most immunoglobulins, making it commercially important. Molecular imprinting is a method based on the selective recognition of various molecules. Molecular imprinted polymers are materials that are easy to prepare, durable, cheap and have molecular recognition capability. Cryogels are prepared by radical polymerization in a partially frozen environment. The unique structure of cryogels combined with osmotic, chemical and mechanical stability make them attractive chromatography matrices for a variety of biological compounds/specimens (plasmids, pathogens, cells). In this protocol, protein A imprinted supermacroporous poly(2-hydroxyethyl methacrylate) cryogels were prepared in spherical form for protein A purification. The characterization of the prepared cryogels were made by swelling test, scanning electron microscopy (SEM), Fourier transform infrared spectrophotometer (FTIR), and Brunauer-Emmett-Teller (BET) surface area analysis. After characterization, optimum conditions for protein A adsorption were determined in the batch system. The maximum protein A adsorption capacity was determined after optimization of the imprinted cryogels. Protein A relative selectivity coefficients of imprinted cryogels were examined for both Fc and protein G. Protein A was isolated from the bacterial cell wall using fast performance liquid chromatography (FPLC). The separated protein A was determined by sodium dodecyl sulfate gel electrophoresis (SDS-PAGE). In the last stage, the reusability of the cryogel was examined.

A Sensitive Capacitive Biosensor for Protein a Detection Using Human IgG Immobilized on an Electrode Using Layer-by-Layer Applied Gold Nanoparticles

A capacitive biosensor for the detection of protein A was developed. Gold electrodes were fabricated by thermal evaporation and patterned by photoresist photolithography. A layer-by-layer (LbL) assembly of thiourea (TU) and HAuCl4 and chemical reduction was utilized to prepare a probe with a different number of layers of TU and gold nanoparticles (AuNPs). The LbL-modified electrodes were used for the immobilization of human IgG. The binding interaction between human IgG and protein A was detected as a decrease in capacitance signal, and that change was used to investigate the correlation between the height of the LbL probe and the sensitivity of the capacitive measurement. The results showed that the initial increase in length of the LbL probe can enhance the amount of immobilized human IgG, leading to a more sensitive assay. However, with thicker LbL layers, a reduction of the sensitivity of the measurement was registered. The performance of the developed system under optimum set-up showed a linearity in response from 1 × 10-16 to 1 × 10-13 M, with the limit detection of 9.1 × 10-17 M, which could be interesting for the detection of trace amounts of protein A from affinity isolation of therapeutic monoclonal antibodies.

Myxovirus resistance protein A activates type I IFN signaling pathway to inhibit Zika virus replication

Myxovirus resistance protein A(MxA), one of the dynamin superfamily of large guanosine triphosphatase and a classical interferon stimulated gene (ISG) induced by type I interferons (IFNs), plays antiviral role in various virus infections. However, the effect of MxA on Zika virus (ZIKV) infection and its underlying mechanism remain elusive. In this study, we aimed to explore the role of MxA in ZIKV infection and its potential mechanisms. MxA overexpression was achieved by transfection with plasmid. The levels of MxA expression and ZIKV replication were assayed by both qRT-PCR and western blot. The activation status of Jak/STAT signaling pathway was evaluated at three levels: phosphorylation of STAT1 and STAT2(p-STAT1, p-STAT2) (western blot), activity of interferon sensitive response element (ISRE) (dual luciferase reporter gene assay), and the expression levels of ISGs (qRT-PCR). Our results showed that MxA overexpression inhibited ZIKV replication with no effect on virus entry. The expression levels of retinoic acid inducible gene I (RIG-I), melanoma differentiation-associated gene-5(MDA5), Toll-like receptor3(TLR3) and interferon regulatory Factor 3(IRF3), as well as IFNα and IFNβ, were increased in parallel with MxA upregulation. Interestingly, the inhibitory effect of MxA on ZIKV replication was abolished in type I IFN receptor (IFNAR) deficient cells (U5A). These data collectively supported that MxA inhibits ZIKV replication through activation of the type I IFN signaling pathway.

One-Step Surface Immobilization of Protein A on Hydrogel Nanofibers by Core-Shell Electrospinning for Capturing Antibodies

Nanofibers (NFs) are potential candidates as filter materials for affinity separation owing to their high liquid permeability based on their high porosity. Multiple and complex processes were conventionally performed to immobilize proteins for modifying NF surfaces. A simple method must be developed to immobilize proteins without impairing their biological activity. Herein, we succeeded in fabricating NFs with a core of cellulose acetate and a shell of hydrophilic polyvinyl alcohol immobilized with staphylococcal recombinant protein A by a one-step process based on core-shell electrospinning. A total of 12.9 mg/cm3 of antibody was captured in the fiber shell through high affinity with protein A immobilized in an aqueous environment of the hydrogel. The maximum adsorption site and dissociation constant evaluated by the Langmuir model were 87.8 µg and 1.37 µmol/L, respectively. The fiber sheet withstood triplicate use. Thus, our NF exhibited high potential as a material for membrane chromatography.

Improving mAb capture productivity on batch and continuous downstream processing using nanofiber PrismA adsorbents

Improving productivity and decreasing costs for biotherapeutic agents has been a focal driving force in the manufacturing of biologics. Advances in upstream processes have been continuously outpacing the ability for downstream operations to purify biologics, especially monoclonal antibodies. Continuous chromatography has several benefits for biologic purification including automated control, decreased labor, improved productivity, and more consistent product attributes. The goal of this study was to improve productivity and decrease costs associated with batch-mode and continuous purification processes. Productivities using cellulose nanofibers with a protein A ligand offer greater than 30-fold higher productivities than their resin-based equivalents using periodic countercurrent technology with multiple column chromatography. The smaller columns needed for convective mass transfer, faster processing times, and decreased costs allow for a more efficient mAb capture step. Additionally, high throughput purification (grams of mAbs/day) can be achieved from the scale-down model developed using periodic countercurrent technology. These advancements will help drive the evolution of downstream operations to manage the higher workloads due to increased upstream titers in a cost-effective manner.

Insight into purification of monoclonal antibodies in industrial columns via studies of Protein A binding capacity by in situ ATR-FTIR spectroscopy

Therapeutic monoclonal antibodies (mAbs) are effective treatments for a range of cancers and other serious diseases, however mAb treatments cost on average ∼$100 000 per year per patient, limiting their use. Currently, industry favours Protein A affinity chromatography (PrAc) as the key step in downstream processing of mAbs. This step, although highly efficient, represents a significant mAb production cost. Fouling of the Protein A column and Protein A ligand leaching contribute to the cost of mAb production by shortening the life span of the resin. In this study, we assessed the performance of used PrAc resin recovered from the middle inlet, center and outlet as well as the side inlet of a pilot-scale industrial column. We used a combination of static binding capacity (SBC) analysis and Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy to explore the used resin samples. SBC analysis demonstrated that resin from the inlet of the column had lower binding capacity than resin from the column outlet. ATR-FTIR spectroscopy with PLS (partial least square) analysis confirmed the results obtained from SBC analysis. Importantly, in situ ATR-FTIR spectroscopy also allowed both measurement of the concentration and assessment of the conformational state of the bound Protein A. Our results reveal that PrAc resin degradation after use is dependent on column location and that neither Protein A ligand leaching nor denaturation are responsible for binding capacity loss.

Genome-wide analysis of the Universal stress protein A gene family in Vitis and expression in response to abiotic stress

Universal Stress Protein A (USPA) plays critical roles in the regulation of growth, development and response to abiotic stress in plants. To date, most research related to the role of USPA in plants has been carried out in herbaceous models such as Arabidopsis, rice and soybean. Here, we used bioinformatics approaches to identify 21 USPA genes in the genome of Vitis vinifera L. Phylogenetic analysis revealed that VvUSPAs could be divided into eight clades. Based on predicted chromosomal locations, we identified 16 pairs of syntenic, orthologous genes between A. thaliana and V. vinifera. Further promoter cis-elements analysis, together with identification of potential microRNA (miRNA) binding sites, suggested that at least some of the VvUSPAs participate in response to phytohormones and abiotic stress. To add support for this, we analyzed the developmental and stress-responsive expression patterns of the homologous USPA genes in the drought-resistant wild Vitis yeshanensis accession 'Yanshan-1' and the drought-sensitive Vitis riparia accession 'He'an'. Most of the USPA genes were upregulated in different degrees in the two genotypes after drought stress and exposure to ethephon (ETH), abscisic acid (ABA) and methyl jasmonate (MeJA). Individual USPA genes showed various tissue-specific expression patterns. Heterologous expression of five selected genes (VvUSPA2, VvUSPA3, VvUSPA11, VvUSPA13 and VvUSPA16) in Escherichia coli (E. coli) enhanced resistance to drought stress. Our study provides a model for mapping gene function in response to abiotic stress and identified three candidate genes, VvUSPA3, VvUSPA11 and VvUSPA16, as regulators of drought response in V. vinifera.

[Eukaryotic expression and immunoactivity of protein A/G-horseradish peroxidase(PA/G-HRP) fusion protein as universal secondary antibody for detection of IgG originating from mice and rabbits]

Objective To prepare universal secondary antibodies those can bind to the IgG from mice and rabbits, and use the antibodies in a variety of immunoassays. Methods The fusion genes of staphylococcal protein A (SPA), streptococcal protein G (SPG), and horseradish peroxidase (HRP) were synthesized, and cloned into the vector pcDNA^TM3.1 to generate the eukaryotic expression plasmids. The plasmids were transiently transfected into HEK293F cells for expression. The fusion protein expressed in the plasmid was detected by SDS-PAGE and Western blotting, and its immunoactivity was measured by Western blotting, ELISA, and immunohistochemical staining. Results Restriction enzyme digestion and gene sequencing showed the pPA-HRP, pPG-HRP, and pPA/G-HRP plasmids were successfully created. Coomassie brilliant blue staining and Western blotting indicated that the fusion proteins PA-HRP, PG-HRP, and PA/G-HRP successfully expressed in HEK293F cells. Western blotting, ELISA, and immunohistochemical staining showed that IgGs derived from mice and rabbits could be recognized and bound by the three kinds of fusion protein, of which the fusion protein PA/G-HRP exhibited the highest affinity. Conclusion The fusion protein PA/G-HRP with high and universal IgG affinity is successfully prepared. The PA/G-HRP can replace traditional secondary antibodies against mouse and rabbit IgG in a variety of immunological assays.

Improving the diagnosis of bovine tuberculosis using gold nanoparticles conjugated with purified protein derivative: special regard to staphylococcal protein A and streptococcal protein G

Different ancillary immunodiagnostic tests were traditionally-established for diagnosis of bovine tuberculosis (BTB) either cellular or humoral as tuberculin skin test (TST), gamma interferon (INF-γ), and indirect enzyme-linked immunosorbent assay (iELISA). These tests had been consumed more time and expensive, and needed sophisticated equipment. To dissolve these problems, serological diagnosis depending on humoral immunity is the aim of this work. Herein, slide-based agglutination test was chosen as a rapid and simple field test based on purified protein derivative (PPD) antigen in addition to some supplementation materials such as Staphylococcal protein A (SPA) and Streptococcal protein G (SPG) to improve detection of BTB antibody in serum samples. Gold nanoparticles (Au NPs) were synthesized by gamma ray, and after complete characterization, the synthesized Au NPs were spherical, small-sized, and stable without any impurities. Addition of such supplementation reagents for serodiagnosis of tuberculosis is of paramount important for the detection of serum antibodies against tuberculosis (TB) and it was considered an easily simple and possible way for improving TB diagnosis. In this work, 70 animals tested positive for TST as well as 20 animals tested negative for TST were used for the diagnosis of BTB depending on humoral immune response based on PPD slide agglutination test using reporter regents (SPA and/or SPG) either native or recombinant. The agglutination density was recorded and read in 4 degrees of positivity with scores ranging from negative (-) to very strong reaction (++++) occurred in different times of agglutination. Groups showed 100% positive reactivates employed in Exp. 1, 2, and 3 with differentiation of slide agglutination test density and was rated from moderate positivity (2+) to very strong (4+), with predominant positivity in density of (3+). Pink-colored intensity is associated with the strengthened reactions between PPD-conjugated Au NPs and serum antibody of each tested samples, which allows for visual rapid, simple, and effective attractive diagnosis of BTB. The specificity and sensitivity of the serological tests were characterized. TST offers the highest sensitivity (83.6%) among the other immunoassays, while the lowest specificity was recorded in TST (57.4%). SPA/SPG offers the best performance in term of combined sensitivity and specificity (performance index) of 175.4. Therefore, the development and uses of detection reagent (such as SPA and/or SPG) slide co-agglutination test (COAT), either native or recombinant (rSPA/SPG) for the detection of TB antibodies based on PPD antigen, as well as the uses of Au NPs rSPA/SPG as detection conjugate based on the same antigen, were also performed as a simple, rapid, sensitive, specific, eco-friendly, and low cost, which shows a great potential in field and lab diagnosis of BTB. So, high reduction in reagents that yields reactions similarly as traditional techniques was needed.

DIP2A is involved in SOD-mediated antioxidative reactions in murine brain

Autism spectrum disorders (ASDs) are highly associated with oxidative stress. We have recently shown that Disconnected-interacting protein homolog 2 A (DIP2A) functions in ASD pathophysiology by regulating cortactin acetylation for spine development and synaptic transmission. However, its role is not fully understood in the context of its abundant expression in mitochondria. In this paper, we found that DIP2A was involved in superoxide dismutase (SOD)-mediated antioxidative reactions. In mice, DIP2A knockout inhibited SOD activity and increased reactive oxygen species (ROS) levels in the cerebral cortex. In vitro gain-of-function experiments further confirmed the positive role of DIP2A in scavenging ROS upon oxidative stress. Moreover, DIP2A knockout caused irregular mitochondrial morphology in the cerebral cortex and impaired mitochondrial metabolism with an over consumption of lipids for energy supply. Taken together, these results revealed unrecognized functions of DIP2A in antioxidative protection, providing another possible explanation for DIP2A-mediated ASD pathophysiology.

Development of Optical Biosensor Using Protein A-Conjugated Chitosan-Gold Nanoparticles for Diagnosis of Cystic Echinococcosis

Human echinococcosis is a serious parasitic diseasethat still affects millions of people in many parts of the world. Since it can offer a critical threat to people's health, it is important to discover a rapid, convenient, and economical method for detection. Herein, we propose a novel point of care assay, namely, an enhanced immuno-dot-blot assay for diagnosis of cystic echinococcosis (hydatidosis). This method is based on the formation of a sandwich complex between a goldnanoprobe (chitosan-gold nanoparticleprotein A) and hydatid cyst antigen (Ag B), which holds anti-Ag B antibodies. Briefly, protein A was conjugated to chitosan-gold nanoparticles via glutaraldehyde chemistry. Then, Ag B was immobilized on the surface of a nitrocellulose membrane, which was followed by the addition of the sera sample and gold nanoprobes. The positive signals were easily detectable by naked eye. The signal intensity of this biosensor was proportional to the concentration of active anti-Echinococcus granulosus antibodies on the surface of the nanoparticles, titer of antibodies in the sera samples, and concentration of Ag B coated on the nitrocellulose membrane. The minimum concentration to use the protein A for conjugation to detect titer of anti-Echinococcus IgGand the concentration of Ag B coated in nitrocellulose membrane were 0.5 and 0.3 mg/mL, respectively. This enhanced immuno-dot-blot assay offers a simple diagnostic technique withoutthe need for expensive equipment for diagnosis of echinococcosis.

Protein A Immunoadsorption Relieves Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy after Unsuccessful Methylprednisolone Treatment

BACKGROUND

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy (GFAP-A) is a recently defined autoimmune inflammatory disease of the central nervous system in which GFAP IgG is present in the cerebrospinal fluid (CSF). Its primary clinical manifestation is meningoencephalitis, and it usually responds well to corticosteroids. Herein, we report a case of a patient with GFAP-A with initial symptoms of psychological and cognitive impairment, which did not respond to high-dose methylprednisolone therapy but was successfully treated with protein A immunoadsorption (PAIA) therapy.

METHODS

GFAP IgG was detected by indirect immunofluorescence assay. The patient's data were analyzed retrospectively.

RESULTS

A 48-year-old man presented with anxiety, depression, cognitive decline, tremor, gait disturbance, and fecal and urine incontinence. Autoimmune GFAP-A was diagnosed based on the following: (1) T2-weighted and fluid-attenuated inversion recovery MRI findings of hypersensitive lesions in the subcortical and deep white matter of the brain, with multiple longitudinally extensive lesions in the cervical and chest regions of the spinal cord, and (2) high levels of GFAP IgG in the CSF. Clinical symptoms and abnormalities detected on neuroimaging worsened after administration of high-dose intravenous methylprednisolone (IVMP) and intravenous immunoglobulin (IVIG) but improved significantly after PAIA therapy.

CONCLUSION

Psychological impairment can be the first sign of autoimmune GFAP-A. PAIA might be an effective treatment for patients with GFAP-A who respond poorly to conventional IVMP and IVIG therapy.

Campylobacter jejuni Serine Protease HtrA Cleaves the Tight Junction Component Claudin-8

Campylobacter jejuni express the high temperature requirement protein A (HtrA), a secreted serine protease, which is implicated in virulence properties of the pathogen. Previous studies have shown that C. jejuni HtrA can cleave the epithelial transmembrane proteins occludin and E-cadherin in the tight and adherens junctions, respectively. In the present report, we studied the interaction of HtrA with another human tight junction protein, claudin-8. Confocal immunofluorescence experiments have shown that C. jejuni infection of the intestinal polarized epithelial cells in vitro leads to a relocation of claudin-8. Wild-type C. jejuni induced the downregulation of claudin-8 signals in the tight junctions and an accumulation of claudin-8 agglomerates in the cytoplasm, which were not seen during infection with isogenic ΔhtrA knockout deletion or protease-inactive S197A point mutants. Western blotting of protein samples from infected vs. uninfected cells revealed that an 18-kDa carboxy-terminal fragment is cleaved-off from the 26-kDa full-length claudin-8 protein, but not during infection with the isogenic ΔhtrA mutant. These results were confirmed by in vitro cleavage assays using the purified recombinant C. jejuni HtrA and human claudin-8 proteins. Recombinant HtrA cleaved purified claudin-8 in vitro giving rise to the same 18-kDa sized carboxy-terminal cleavage product. Mapping studies revealed that HtrA cleavage occurs in the first extracellular loop of claudin-8. Three-dimensional modeling of the claudin-8 structure identified an exposed HtrA cleavage site between the amino acids alanine 58 and asparagine 59, which is in well agreement with the mapping studies. Taken together, HtrA operates as a secreted virulence factor targeting multiple proteins both in the tight and adherens junctions. This strategy may help the bacteria to open the cell-to-cell junctions, and to transmigrate across the intestinal epithelium by a paracellular mechanism and establish an acute infection.

Fish as an alternative protein - A consumer-oriented perspective on its role in a transition towards more healthy and sustainable diets

Fish has several benefits that make it a desirable part of a healthy diet. It is also a high-protein product that can be used as a relatively efficient meat replacer. Both from a health and sustainability perspective, however, it is important to consider the optimum number of fish servings per week and to examine whether fish and plant protein can be brought under the same heading of alternative protein sources. To explore the consumer perspective on these issues, this paper draws on a brief literature study and a re-analysis of survey data from the Netherlands collected earlier. The hypothesis was that affinities with fish consumption and plant-based protein sources are to a certain extent related to each other, based on common relationships with food involvement, which set them apart from meat. The results showed that the hypothesis needed to be nuanced: fish consumption was associated exclusively with affinity with spicy meals based on authentic plant protein sources (e.g. nuts) and this relationship was partially based on food involvement. The results are in line with current Dutch recommendations that encourage consumers to eat one serving of fish per week and that stimulate those who already eat more than one serving of fish to replace the rest by plant-based protein sources.

Myxovirus Resistance Protein A Is a Useful Additional Histological Marker in Suspected Cutaneous Lupus Erythematosus

is missing (Short communication).

Antibacterial Effect of Silver Nanomaterials on Staphylococcal Protein A by Molecular Dynamics Simulation

Nanotechnologies have changed this world in various aspects including the oral medicine. It has been demonstrated that silver (Ag) nanomaterials can exhibit strong inhibition and killing effect on oral bacteria. Furthermore, the Ag nanomaterials have superb antimicrobial activity and nonacute toxic effects on human cells. Previously, the impact of Ag on oral bacteria was demonstrated by experiments. In this work, we applied molecular dynamics (MD) simulations to investigate the influence of Ag nanomaterials on oral bacteria. Firstly, by comparing change of molecular structure of staphylococcal protein A (SPA) with and without Ag, we found that Ag nanomaterials have strong effect on evolution of protein secondary structure of SPA. Secondly, it was observed that Ag has negligible effect on Solvent Accessible Surface Area (SASA) of SPA indicating that the Ag only changed its microstructure. Finally, it was found that the average amount of hydrogen bond in SPA was reduced in the presence of Ag which was origin of antimicrobial activity of Ag. It is believed that the growing interest in dental medicine with nanomaterials would lead molecular dynamics simulations to be an effective method for studying inhibition and killing pathological process of nanomaterials on oral bacteria.

Activated Cross-linked Agarose for the Rapid Development of Affinity Chromatography Resins - Antibody Capture as a Case Study

The purification of monoclonal antibodies (mAbs) is commonly achieved by Protein A affinity chromatography, which can account for up to 25% of the overall process costs. Alternative, cost-effective capture steps are therefore valuable for industrial-scale manufacturing, where large quantities of a single mAb are produced. Here we present a method for the immobilization of a DsRed-based epitope ligand to a cross-linked agarose resin allowing the selective capture of the HIV-neutralizing antibody 2F5 from crude plant extracts without using Protein A. The linear epitope ELDKWA was first genetically fused to the fluorescent protein DsRed and the fusion protein was expressed in transgenic tobacco (Nicotiana tabacum) plants before purification by immobilized metal-ion affinity chromatography. Furthermore, a method based on activated cross-linked agarose was optimized for high ligand density, efficient coupling and low costs. The pH and buffer composition and the soluble ligand concentration were the most important parameters during the coupling procedure, which was improved using a design-of-experiments approach. The resulting affinity resin was tested for its ability to selectively bind the target mAb in a crude plant extract and the elution buffer was optimized for high mAb recovery, product activity and affinity resin stability. The method can easily be adapted to other antibodies with linear epitopes. The new resins allow gentler elution conditions than Protein A and could also reduce the costs of an initial capture step for mAb production.

CRISPR/Cas9-Mediated Knockout of MicroRNA-744 Improves Antibody Titer of CHO Production Cell Lines

MicroRNAs (miRNAs) are noncoding RNAs that serve as versatile molecular engineering tools to improve production cells by overexpression or knockdown of miRNAs showing beneficial or adverse effects on cell-culture performance. The genomic knockout (KO) of noncoding RNAs in Chinese hamster ovary (CHO) production cells has not been reported. However, given the significant number of miRNAs showing negative effects on CHO-bioprocess performance and the development of clustered regularly interspaced short palindromic repeats/CRISPR-associated proteins (CRISPR/Cas9), genome editing tools facilitate precise optimization of CHO cells via modulation of noncoding RNAs. In a previous high-content miRNA screen, miR-744 was identified as a potential target associated with reduced productivity. Hence, the genomic miR-744 precursor sequence is deleted by two single guide RNA (sgRNA)-Cas9-mediated DNA double-strand breaks (DSB) flanking the miR-744 locus. After fluorescence-activated cell sorting (FACS), clonal miR-744 KO cell lines are recovered and three of them are confirmed as miR-744 KOs. Impacts of CRISPR/Cas9 editing are characterized at the genetic, transcript, and phenotypic levels. During batch cultivation, antibody titers of miR-744 KOs are significantly increased to 190-311 mg L-1 compared to a nontargeting (NT) sgRNA transfected clonal control with 156 mg L-1 , pointing towards the potential of miRNA KO for cell line engineering.

Optimization of Sequence, Display, and Mode of Operation of IgG-Binding Peptide Ligands to Develop Robust, High-Capacity Affinity Adsorbents That Afford High IgG Product Quality

This work presents the use of peptide ligand HWRGWV and its cognate sequences to develop affinity adsorbents that compete with Protein A in terms of binding capacity and quality of the eluted product. First, the peptide ligand was conjugated to crosslinked agarose resins (WorkBeads) at different densities and using different spacer arms. The optimization of ligand density and display resulted in values of static and dynamic binding capacity of 85 mg/mL and 65 mg/mL, respectively. A selected peptide-WorkBeads adsorbent was utilized for purifying Mabs from Chinese Hamster Ovary (CHO) cell culture supernatants. The peptide-WorkBeads adsorbent was found able to withstand sanitization with strong alkaline solutions (0.5 M NaOH). The purity of the eluted product was consistently higher than 95%, with logarithmic removal value (LRV) of 1.5 for host cell proteins (HCPs) and 4.0 for DNA. HCP clearance was significantly improved by adding a post-load washing step with either 0.1 M Tris HCl pH 9 or 1 M NaCl. The cognate peptide of HWRGWV, constructed by replacing arginine (R) with citrulline, further increased the HCP LRV to 2.15. The peptide-based adsorbent also showed a remarkable performance in terms of removal of Mab aggregates; unlike Protein A, in fact, HWRGWV was found to bind only monomeric IgG. Collectively, these results demonstrate the potential of peptide-based adsorbents as alternative to Protein A for the purification of therapeutic antibodies.