Antigenic Structure Research Articles

Cross-Reactivity between Chemical Antibodies Formed to Serum Proteins and Thyroid Axis Target Sites.

In some instances, when chemicals bind to proteins, they have the potential to induce a conformational change in the macromolecule that may misfold in such a way that makes it similar to the various target sites or act as a neoantigen without conformational change. Cross-reactivity then can occur if epitopes of the protein share surface topology to similar binding sites. Alteration of peptides that share topological equivalence with alternating side chains can lead to the formation of binding surfaces that may mimic the antigenic structure of a variant peptide or protein. We investigated how antibodies made against thyroid target sites may bind to various chemical–albumin compounds where binding of the chemical has induced human serum albumin (HSA) misfolding. We found that specific monoclonal or polyclonal antibodies developed against thyroid-stimulating hormone (TSH) receptor, 5′-deiodinase, thyroid peroxidase, thyroglobulin, thyroxine-binding globulin (TBG), thyroxine (T4), and triiodothyronine (T3) bound to various chemical HSA compounds. Our study identified a new mechanism through which chemicals bound to circulating serum proteins lead to structural protein misfolding that creates neoantigens, resulting in the development of antibodies that bind to key target proteins of the thyroid axis through protein misfolding. For demonstration of specificity of thyroid antibody binding to various haptenic chemicals bound to HSA, both serial dilution and inhibition studies were performed and proportioned to the dilution. A significant decline in these reactions was observed. This laboratory analysis of immune reactivity between thyroid target sites and chemicals bound to HSA antibodies identifies a new mechanism by which chemicals can disrupt thyroid function.

MLST based serotype prediction for the accurate identification of non typhoidal Salmonella serovars.

Traditional serotyping based on the phenotypic variation of O- and H-antigen remains as the gold-standard for the identification and classification of Salmonella isolates for last 70years. Although this classification is a globally recognized nomenclature, huge diversity of Salmonella serotypes have made the serovar identification to be very complex. Seven gene multilocus sequence typing (MLST) on the other hand can provide serovar prediction as well as the evolutionary origin between the serovars. In this study non typhoidal Salmonella (NTS) strains (n = 45) isolated from clinical samples (blood, faeces and pus) were identified by traditional phenotypic serotyping and biochemical testing. All the tested Salmonella isolates were designated as serovar Typhimurium based on phenotyping. However, by MLST 60% (27/45) of the isolates were S. Typhimurium, 35.5% (16/45) were S. Agona (ST13), 2.2% (1/45) were S. Kentucky (ST198) and 2.2% (1/45) were S. Saintpaul (ST27). MLST analysis assigned S. Typhimurium isolates as ST36 (18/127), ST19 (7/27) and ST313 (2/27). Mismatches in serovar designation between MLST database and phenotypic serotyping can be due to the misinterpretation of phenotypic serotyping as the antigenic structures of S. Typhimurium, S. Agona differs by a surface antigen. MLST based phylogeny of study isolates showed clustering according to sequence types. Concordance between MLST based sequence type and phenotypic serotype is important to provide insights into genetic population structure of Salmonella.

Identification of the Pseudomonas aeruginosa O17 and O15 O-Specific Antigen Biosynthesis Loci Reveals an ABC Transporter-Dependent Synthesis Pathway and Mechanisms of Genetic Diversity.

Many bacterial cell surface glycans, such as the O antigen component of lipopolysaccharide (LPS), are produced via the so-called Wzx/Wzy- or ABC transporter-dependent pathways. O antigens are highly diverse polysaccharides that protect bacteria from their environment and engage in important host-pathogen interactions. The specific structure and composition of O antigens are the basis of classifying bacteria into O serotypes. In the opportunistic pathogen Pseudomonas aeruginosa, there are currently 20 known O-specific antigen (OSA) structures. The clusters of genes responsible for 18 of these O antigens have been identified, all of which follow the Wzx/Wzy-dependent pathway and are located at a common locus. In this study, we located the two unidentified O antigen biosynthesis clusters responsible for the synthesis of the O15 and the O17 OSA structures by analyzing published whole-genome sequence data. Intriguingly, these clusters were found outside the conserved OSA biosynthesis locus and were likely acquired through multiple horizontal gene transfer events. Based on data from knockout and overexpression studies, we determined that the synthesis of these O antigens follows an ABC transporter-dependent rather than a Wzx/Wzy-dependent pathway. In addition, we collected evidence to show that the O15 and O17 polysaccharide chain lengths are regulated by molecular rulers with distinct and variable domain architectures. The findings in this report are critical for a comprehensive understanding of O antigen biosynthesis in P. aeruginosa and provide a framework for future studies.IMPORTANCEP. aeruginosa is a problematic opportunistic pathogen that causes diseases in those with compromised host defenses, such as those suffering from cystic fibrosis. This bacterium produces a number of virulence factors, including a serotype-specific O antigen. Here, we identified and characterized the gene clusters that produce the O15 and O17 O antigens and show that they utilize a pathway for synthesis that is distinct from that of the 18 other known serotypes. We also provide evidence that these clusters have acquired mutations in specific biosynthesis genes and have undergone extensive horizontal gene transfer within the P. aeruginosa population. These findings expand on our understanding of O antigen biosynthesis in Gram-negative bacteria and the mechanisms that drive O antigen diversity.

Nucleophosmin, Coilin, and Argentophilic (AgNOR) Proteins in the Neurons of Human Substantia Nigra

The aim of the work was to study the intranuclear distribution of nucleophosmin (B23), coilin (p80), AgNOR proteins, and nonheme iron in the neurons of the human substantia nigra. Fragments of the human midbrain (n = 10) were shown to have no signs of neurodegeneration. The material was fixed in zinc–ethanol–formaldehyde, a special fixative that provides high preservation of antigenic determinants and tissue structures. This work revaled a new data on molecular and structural organization of the nucleoli of neurons in human substantia nigra. It was found that, in the nuclei of substantia nigra neurons, there is only one large nucleolus, and its size varies between individuals (from 4.2 ± 0.4 to 6.2 ± 0.6 μm in diameter). Nucleophosmin is concentrated solely in the nucleolus and is unevenly distributed in it. Cajal bodies found in the nucleus of most substantia nigra neurons are coiline-containing structures of round or oval shape and about 1 μm in size. Coilin accumulation has also been noted in numerous intranuclear microstructures, which significantly differ in their localization and morphological characteristics from typical Cajal bodies. AgNOR proteins are present in the substantia nigra neurons and are very variably distributed. Nonheme iron was detected in the nucleoli ofof some substantia nigra neurons. In some cases iron was concentrated in the giant fibrillar center (GFC). The data obtained will contribute to a clearer understanding of the role of nucleolar proteins in the functioning of dopaminergic neurons in the human brain and the determination of molecular sensors of nucleolar stress observed during neurodegeneration.

HLA DRB1*15:01-DQB1*06:02-Restricted Human CD4+ T Cells Are Selectively Activated With Amoxicillin-Peptide Adducts.

Amoxicillin-clavulanate is the most common cause of idiosyncratic drug-induced liver injury (DILI). Drug-specific CD4+ T cells have been detected in patients with DILI, suggestive of an immune etiology. Furthermore, genetic associations including the human leucocyte antigen (HLA) DRB1*15:01-DQB1*06:02 haplotype influence susceptibility. Amoxicillin forms protein adducts that are postulated to activate T cells, by conjugating with lysine residues. However, a role for such adducts has not been described. This study aimed to (1) investigate whether amoxicillin-modified HLA-DRB1*15:01-DQB1*06:02 binding peptides selectively activate DILI patient T cells and (2) define the nature of the T-cell response with respective to antigen structure. Peptides carrying lysine residues for amoxicillin binding in positions (KP) 2-6 and anchors for the HLA-DRB1*15:01-DQB1*06:02 haplotype were designed. The amoxicillin-modified peptides were characterized by mass spectrometry prior to culturing with patient peripheral blood mononuclear cell. T-cell clones were then tested for specificity with amoxicillin, unmodified- and amoxicillin-modified peptides, and structural variants. Amoxicillin-modified KP-2 and KP-3 peptide-specific CD4+ clones proliferated and secreted interferon gamma (IFN-γ), interleukin (IL)-10, perforin and/or IL-17/IL-22 in a dose-dependent manner and displayed no cross-reactivity with amoxicillin, unmodified peptide or with positional derivatives. The T cells response was HLA class II restricted and the amoxicillin-modified peptides bound selectively to HLA-DRB1*15:01 and/or DQB1*06:02. To conclude, we show that amoxicillin-modified peptides bind to both components of the risk haplotype to stimulate DILI patient T cells and describe the importance of the position of nucleophilic lysine residue in the HLA binding peptide sequence.

Glycan-Modified Virus-like Particles Evoke T Helper Type 1-like Immune Responses.

Dendritic cells (DCs) are highly effective antigen-presenting cells that shape immune responses. Vaccines that deliver antigen to the DCs can harness their power. DC surface lectins recognize glycans not typically present on host tissue to facilitate antigen uptake and presentation. Vaccines that target these surface lectins should offer improved antigen delivery, but their efficacy will depend on how lectin targeting influences the T cell subtypes that result. We examined how antigen structure influences uptake and signaling from the C-type lectin DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin or CD209). Virus-like particles (VLPs) were engineered from bacteriophage Qβ to present an array of mannoside ligands. The VLPs were taken up by DCs and efficiently trafficked to endosomes. The signaling that ensued depended on the ligand displayed on the VLP: only those particles densely functionalized with an aryl mannoside, Qβ-Man540, elicited DC maturation and induced the expression of the proinflammatory cytokines characteristic of a T helper type 1 (TH1)-like immune response. This effect was traced to differential binding to DC-SIGN at the acidic pH of the endosome. Mice immunized with a VLP bearing the aryl mannoside, and a peptide antigen (Qβ-Ova-Man540) had antigen-specific responses, including the production of CD4+ T cells producing the activating cytokines interferon-γ and tumor necrosis factor-α. A TH1 response is critical for intracellular pathogens (e.g., viruses) and cancer; thus, our data highlight the value of targeting DC lectins for antigen delivery and validate the utility of DC-targeted VLPs as vaccine vehicles that induce cellular immunity.

Behavioral response and genotypical features of grazing sheep in arid zone

The issues of natural pastures with different intensities of grazing and behavioral response of fine-wool and hair sheep, genotypic characteristics of sheep by blood groups, variability in antigen frequencies, and their relationship with the adaptability of various sheep breeds to a grazing system are of particular interest. The behavior of sheep in grazing was studied in bands of ewes of hair fat-tailed Kalmyk, Edilbay, and fine-wool Grozny sheep breeds in the agricultural production cooperative Kirovsky, the Republic of Kalmykia. Under extensive grazing, pastures had a high yield of air-dry mass in June at the end of the growing season of steppe plant species, with Gramineae in the associations being more actively grazed than wormwood. Grazing hair sheep of the Kalmyk breed kept pasture 1.4 (P<0.01) times more productive than fine-wool sheep at an average load and 1.3 times at a low load. A favorable forecast for the development of natural pastures in the Republic of Kalmykia was the 1:2 ratio between Asterácea and Poáceae in the first two or three years of grazing and 1:1 in the ensuing years. The antigen pool of the Grozny breed was significantly different from antigens of hair breed. The antigen structure of the Edilbay breed was similar to the Kalmyk one. The blood group studies showed that the fine-wool and hair breeds had high antigenic similarities in terms of the O antigen, with its frequency of 0.879-0.724. The Cb antigen of the C system was frequent; almost all sheep, regardless of the breed, had the gene in 0.592-0.652 cases.

Algorithm for the use of allergy tests

The article describes the current practice of the relationship between clinicians and laboratory doctors.The dependence in the formation of the list and content of laboratory services on the tasks put forward by the clinician is traced. These may be tests based solely on extractable markers, tests may include extract components, it is possible that in the future the tests will be epitope.The process of protein resorption into the internal environment of a macroorganism is described. The extremely important role of the microbiome of the mucous membranes and the skin in the translational destruction of protein structures is emphasized. The determining factor is that the path of penetration, bypassing the habitat of the microbiome, does not exist. The emphasis is placed on the fact that an allergological reaction is possible only in the case where protein destruction does not lead to complete degradation to amino acids, preserved protein structures, penetrating into the internal environment, are perceived by the immune system as an antigen (allergen) with the subsequent launch of a cascade of humoral and cellular reactions. This suggests that the basis of the pathogenesis of an allergic disease is the insufficiency of protein destruction factors, which are involved both from the macroorganism and from the microbiome.Normalization of the functioning of these factors should lead to the recovery of the allergic patient. ASIT should be considered as a palliative. The main and only resorption mechanism is passive diffusion. The determining role of the degree of dissociation of electrolyte solutions created by protein molecules is estimated. The microbiome is presented as an additional organ, chimeric for a macroorganism, whose role is to form barrier, protective functions, preventing the penetration of antigenic structures into the internal environment. It is concluded that the main task of the allergist doctor at the stage of diagnosis should be the desire to identify sensitization to protein homologs that make up one group. This approach makes it possible to assess the spread of sensitizationamong proteins of homologs of various nature of origin, thereby assessing the most widespread pathological process in a particular patient. Laboratory tests for the production of Simesta take into account the ideas presented, for this reason they are arranged in a system with a thought-out sequence of use, depending on the clinical manifestations and the results of the previous study. In the line of proposals there are tests of the original layout, not offered by other manufacturers. These are linear blots collected exclusively on a group basis, namely the Profilins Polcalcins blot, the PR-10, nsLTP blot, the Storageproteins blot, the Serum albumins, Lipocalins blot, the Tropomyosins blot. The test application algorithm is divided into three levels, flexibly using with reference to a specific clinical situation, the clinician’s doctor has the opportunity to obtain the most possible information at the lowest possible cost. Assessing the prospects for the development of allergology, an assumption is made about the development with subsequent implementation of epitope tests into practice, the results of the study on which will make it possible using mathematical tools to model the structure of the protein structure that has penetrated the internal environment. This will determine the missing factors of the destruction of the allergen in a particular patient, which will lead to pathogenetic treatment.

Patterns of 1,748 Unique Human Alloimmune Responses Seen by Simple Machine Learning Algorithms.

Allele specific antibody response against the polymorphic system of HLA is the allogeneic response marker determining the immunological risk for graft acceptance before and after organ transplantation and therefore routinely studied during the patient's workup. Experimentally, bead bound antigen- antibody reactions are detected using a special multicolor flow cytometer (Luminex). Routinely for each sample, antibody responses against 96 different HLA antigen groups are measured simultaneously and a 96-dimensional immune response vector is created. Under a common experimental protocol, using unsupervised clustering algorithms, we analyzed these immune intensity vectors of anti HLA class II responses from a dataset of 1,748 patients before or after renal transplantation residing in a single country. Each patient contributes only one serum sample in the analysis. A population view of linear correlations of hierarchically ordered fluorescence intensities reveals patterns in human immune responses with striking similarities with the previously described CREGs but also brings new information on the antigenic properties of class II HLA molecules. The same analysis affirms that “public” anti-DP antigenic responses are not correlated to anti DR and anti DQ responses which tend to cluster together. Principal Component Analysis (PCA) projections also demonstrate ordering patterns clearly differentiating anti DP responses from anti DR and DQ on several orthogonal planes. We conclude that a computer vision of human alloresponse by use of several dimensionality reduction algorithms rediscovers proven patterns of immune reactivity without any a priori assumption and might prove helpful for a more accurate definition of public immunogenic antigenic structures of HLA molecules. Furthermore, the use of Eigen decomposition on the Immune Response generates new hypotheses that may guide the design of more effective patient monitoring tests.

Toxoplasma gondii Recombinant Antigens in the Serodiagnosis of Toxoplasmosis in Domestic and Farm Animals.

Simple SummaryThe very common parasite infections in animals are caused by members of Apicomplexa, including Toxoplasma gondii, Neospora sp., and Sarcocystis sp. These parasites pose serious veterinary problems. For example, the development of unambiguous diagnostic algorithms and determining the correct diagnosis are hindered by the similar antigenic structure of these parasites, as well as the multitude of similar disease symptoms presented in an infected animal. The intracellular parasite, T. gondii, infects a wide range of warm-blooded animals, including humans. This parasite is widespread among different animal populations, contributes to the loss of reproductive and malformations in young individuals, and can become a serious economic concern for farmers. Additionally, the consumption of undercooked or raw meat and the consumption of improperly processed milk product derived from farm animals are the main parasite transmission routes in humans. This work reviews potential improvements to diagnostic techniques that use recombinant antigens for serodiagnosis of toxoplasmosis in various species of animals.Toxoplasmosis is caused by an intracellular protozoan, Toxoplasma gondii, and is a parasitic disease that occurs in all warm-blooded animals, including humans. Toxoplasmosis is one of the most common parasitic diseases of animals and results in reproductive losses. Toxoplasmosis in humans is usually caused by eating raw or undercooked meat or consuming dairy products containing the parasite. Diagnosis of toxoplasmosis is currently based on serological assays using native antigens to detect specific anti-T. gondii antibodies. Due to the high price, the available commercial agglutination assays are not suited to test a large number of animal serum samples. The recent development of proteomics elucidated the antigenic structure of T. gondii and enabled the development of various recombinant antigens that can be used in new, cheaper, and more effective diagnostic tools. Continuous development of scientific disciplines, such as molecular biology and genetic engineering, allows for the production of new recombinant antigens and provides the basis for new diagnostic tests for the detection of anti-T. gondii antibodies in animal serum samples.

Sambucus nigra (black elder) as alternative treatment for cold and flu

Common cold and flu are caused by common respiratory viral pathogens, which results in hospitalization and death in the world. Among the viral infections, influenza viruses have worldwide spread with major effects on health of societies. Change in antigenic structures of influenza viruses is associated with the lack of effective treatments. Therefore, the use of herbal medicine as alternative choice can be used for management of flu and cold. The flowers of Sambucus nigra or black elders have been approved by commission E for cold, and flu. Although, elders are used in different herbal formulates, but there is no comprehensive study. The subject of this review article was to summarize the efficacy of black elder in treatment of cold and flu. For preparing this manuscript, the electronic resources, books, and thesis were searched by key words of Sambucus, elder, cold, flu, and viral infections. The results of investigations exhibited that there are four clinical trials for elder berries, which it reduced the cold duration and severity (fever, pain, congestion, cough), while there is no clinical trial for elder flower on common cold and flu in spite of its approval by commission E. So, evaluating the efficacy of elder flowers in comparison with its berries and standard treatment on patients with viral respiratory infections should be the subject of large clinical studies.

Characterization of humoral and cellular immune features of gamma-irradiated influenza vaccine

ABSTRACT The most widely used influenza vaccines are prepared by chemical inactivation. However, chemical, especially formalin, treatment-induced modifications of the antigenic structure of the virus are frequently associated with adverse effects including low efficacy of protection, unexpected immune responses, or exacerbation of disease. Gamma-irradiation was suggested as an alternative influenza virus inactivation method due to its great features of completely inactivating virus while not damaging the structures of protein antigens, and cross-protective ability against heterologous strains. However, immunological features of gamma radiation-inactivated influenza vaccine have not been fully understood. In this study, we aimed to investigate the humoral and cellular immune responses of gamma radiation-inactivated influenza vaccine. The gamma irradiation-inactivated influenza vaccine (RADVAXFluA) showed complete viral inactivation but retained normal viral structure with functional activities of viral protein antigens. Intranasal immunization of RADVAXFluA provided better protection against influenza virus infection than formalin-inactivated influenza virus (FIV) in mice. RADVAXFluA greatly enhanced the production of virus-specific serum IgG and alveolar mucosal IgA, which effectively neutralized HA (hemagglutinin) and NA (neuraminidase) activities, and blocked viral binding to the cells, respectively. Further analysis of IgG subclasses showed RADVAXFluA-immunized sera had higher levels of IgG1 and IgG2a than those of FIV-immunized sera. In addition, analysis of cellular immunity found RADVAXFluA induced strong dendritic cells (DC) activation resulting in higher DC-mediated activation of CD8+ T cells than FIV. The results support improved immunogenicity by RADVAXFluA.

Cryo-electron microscopy structure and potential enzymatic function of human six-transmembrane epithelial antigen of the prostate 1 (STEAP1)

Six-transmembrane epithelial antigen of the prostate 1 (STEAP1) is an integral membrane protein that is highly up-regulated on the cell surface of several human cancers, making it a promising therapeutic target to manage these diseases. It shares sequence homology with three enzymes (STEAP2–STEAP4) that catalyze the NADPH-dependent reduction of iron(III). However, STEAP1 lacks an intracellular NADPH-binding domain and does not exhibit cellular ferric reductase activity. Thus, both the molecular function of STEAP1 and its role in cancer progression remain elusive. Here, we present a ∼3.0-Å cryo-EM structure of trimeric human STEAP1 bound to three antigen-binding fragments (Fabs) of the clinically used antibody mAb120.545. The structure revealed that STEAP1 adopts a reductase-like conformation and interacts with the Fabs through its extracellular helices. Enzymatic assays in human cells revealed that STEAP1 promotes iron(III) reduction when fused to the intracellular NADPH-binding domain of its family member STEAP4, suggesting that STEAP1 functions as a ferric reductase in STEAP heterotrimers. Our work provides a foundation for deciphering the molecular mechanisms of STEAP1 and may be useful in the design of new therapeutic strategies to target STEAP1 in cancer.

Pertussis vaccination: problems, possible solutions

Relevance. The growth of pertussis is observed in all countries of the world. The main reasons for this are: decreased level of vaccination, loss of antibodies after vaccination, new methods of examination, changes in the antigenic structure of the pathogen. Solution: vaccination of pregnant women, increasing the level of vaccination, age-related revaccinations. The prospect is to create new vaccines. Purpose. Determine the frequency of untimely vaccination against whooping cough in children of the first years of life, the duration of immunity preservation after the completed set of vaccinations, and the rationale for the catch-up immunization scheme. Results. The timeliness of vaccination was evaluated in 675 children according to vaccination certificates and form112/y. It turned out that 9,21% of children received the first vaccination after a first year old, the second – already 24,10%, the third more than 34%. 49,75% of children included in the analysis had revaccination by the 2 year old. Antibody titers were evaluated after vaccination and 1 revaccination in 114 children with informed parental consent. Through the year after whole cell vaccine did not have protective titers of 17 of the 58 children (29,3%), the grafted acellular – 15 of 56 (26.8 percent). After 3 years was examined 39 children (25 – grafted acellular vaccine and the whole-cell 14). 44,0% (11 children) and 50,0% (7 children) did not have protective titers, respectively. The data coincided with the results of serological monitoring of Rospotrebnadzor in St. Petersburg. The need for catch-up immunization and the introduction of age-related revaccinations against pertussis was confirmed. Catch-up immunization schemes have been developed. Conclusions . Almost half of children are vaccinated with a violation of the calendar, the primary complex of vaccinations, both whole-cell and acellular vaccines, does not provide long-term protection. It is necessary to introduce catchup immunization and age-related revaccinations.

Expression Pattern of the Pneumocystis jirovecii Major Surface Glycoprotein Superfamily in Patients with Pneumonia.

The human pathogen Pneumocystis jirovecii harbors 6 families of major surface glycoproteins (MSGs) encoded by a single gene superfamily. MSGs are presumably responsible for antigenic variation and adhesion to host cells. The genomic organization suggests that a single member of family I is expressed at a given time per cell, whereas members of the other families are simultaneously expressed. We analyzed RNA sequences expressed in several clinical samples, using specific weighted profiles for sorting of reads and calling of single-nucleotide variants to estimate the diversity of the expressed genes. A number of different isoforms of at least 4 MSG families were expressed simultaneously, including isoforms of family I, for which confirmation was obtained in the wet laboratory. These observations suggest that every single P. jirovecii population is made of individual cells with distinct surface properties. Our results enhance our understanding of the unique antigenic variation system and cell surface structure of P. jirovecii.

Chapter 2b: The molecular antigenic structure of the TBEV

TBEV-particles are assembled in an immature, noninfectious form in the endoplasmic reticulum by the envelopment of the viral core (containing the viral RNA) by a lipid membrane associated with two viral proteins, prM and E. Immature particles are transported through the cellular exocytic pathway and conformational changes induced by acidic pH in the trans-Golgi network allow the proteolytic cleavage of prM by furin, a cellular protease, resulting in the release of mature and infectious TBE-virions. The E protein controls cell entry by mediating attachment to as yet ill-defined receptors as well as by low-pH-triggered fusion of the viral and endosomal membrane after uptake by receptor-mediated endocytosis. Because of its key functions in cell entry, the E protein is the primary target of virus neutralizing antibodies, which inhibit these functions by different mechanisms. Although all flavivirus E proteins have a similar overall structure, divergence at the amino acid sequence level is up to 60 percent (e.g. between TBE and dengue viruses), and therefore cross-neutralization as well as (some degree of) cross-protection are limited to relatively closely related flaviviruses, such as those constituting the tick-borne encephalitis serocomplex.

Erratum to: Identification of Tn antigen O-GalNAc-expressing glycoproteins in human carcinomas using novel anti-Tn recombinant antibodies.

The Tn antigen is a neoantigen abnormally expressed in many human carcinomas and expression correlates with metastasis and poor survival. To explore its biomarker potential, new antibodies are needed that specifically recognize this antigen in tumors. Here we generated two recombinant antibodies to the Tn antigen, Remab6 as a chimeric human IgG1 antibody and ReBaGs6 as a murine IgM antibody and characterized their specificities using multiple biochemical and biological approaches. Both Remab6 and ReBaGs6 recognize clustered Tn structures, but most importantly do not recognize glycoforms of human IgA1 that contain potential cross-reactive Tn antigen structures. In flow cytometry and immunofluorescence analyses, Remab6 recognizes human cancer cell lines expressing the Tn antigen, but not their Tn-negative counterparts. In immunohistochemistry (IHC), Remab6 stains many human cancers in tissue array format but rarely stains normal tissues and then mostly intracellularly. We used these antibodies to identify several unique Tn-containing glycoproteins in Tn-positive Colo205 cells, indicating their utility for glycoproteomics in future biomarker studies. Thus, recombinant Remab6 and ReBaGs6 are useful for biochemical characterization of cancer cells and IHC of tumors and represent promising tools for Tn biomarker discovery independently of recognition of IgA1.

Коронавірусні інфекції тварин і птиці в контексті пандемічного поширення коронавірусної хвороби людей COVID-19 (стан і перспективи розв’язання проблеми)

Goal. Because of significant spread in the modern world of coronavirus infection of a man of a new type (COVID-19), caused by a virus SARS-CoV-2, to provide professional analysis of the nature and biological characteristics of coronaviruses of animals, their evolutionary and phylogenetic relationships with coronaviruses of a man, as well as to outline prospects for the use of animal coronaviruses in the creation of a system of countermeasures against pandemic COVID-19. Methods. The generalized literature data and the review of the achievements of scientists of NSC «IECVM» in the control of coronavirus infections in cattle and poultry are submitted for consideration. Results. Classification and phylogenetic relationships in the family Coronaviridae are given, as well as the review of own and literature data on the genetic and antigenic structure of coronavirus cattle. They characterized the direction of the creation of means of control of coronavirus infection of cattle (development of vaccines and diagnosticums). Circulation is established of the virus of infectious bronchitis of chickens «D 388 (QX)», «Italy 02», «4/91», «M41» in poultry farms of Ukraine. The immunity against infectious bronchitis of chickens is 93–100%. In the process of developing modern vaccine preparation for prevention of infectious diseases in poultry (Newcastle disease, infectious bronchitis of chickens and syndrome of decreased egg production) it is established that formaldehyde and ethylenimine completely inactivate the infectivity of the pathogens of the infections, while antigenic activity remains at a high level. The data are given of scientific researches in the ecology and biology of coronavirus infectious bronchitis of chickens, as well as in the study of the ultrastructure of the virus. Conclusions. Knowledge of biological properties and features of mammalian and poultry coronaviruses can be successfully applied in the tests on the effectiveness of control agents (medicines and disinfectants), for preventive actions (creation of «candidate» of vaccines), and control over Covid-19 infection.

Development of an Enzyme-Mediated, Site-Specific Method to Conjugate Toll-Like Receptor 2 Agonists onto Protein Antigens: Toward a Broadly Protective, Four Component, Group A Streptococcal Self-Adjuvanting Lipoprotein-Fusion Combination Vaccine.

Subunit vaccines composed of protein antigens covalently attached to Toll-like receptor (TLR) agonists elicit superior immune responses compared to mixtures of antigens and TLR agonists. Among different conjugation approaches, enzyme-mediated ligation is one of the few that provides an opportunity for the generation of homogeneous, molecularly defined products in which protein antigens are maintained with native structures, which is most critical to elicit protective immune responses upon vaccination. Four highly conserved protein antigens from Group A Streptococcus (GAS) have the potential to be safe and efficacious vaccine candidates. After a TLR2 agonist fibroblast-stimulating lipopeptide-1 (FSL-1) was successfully attached onto each antigen using sortase A and techniques for their purification were developed, a combination vaccine containing interleukin 8 (IL-8) protease (Streptococcus pyogenes cell envelope proteinase [SpyCEP]), Group A Streptococcal C5a peptidase (SCPA), anchorless virulence factor arginine deiminase (ADI), and trigger factor (TF)-TLR2 conjugates was produced. This combination was assessed for immunity in mice and compared with mixtures of the four antigens with FSL-1 or alum. High titer antigen-specific IgG antibodies were detected from all vaccine groups, with antibodies elicited from FSL-1 conjugates around 10-fold higher compared to the FSL-1 mixture group. Furthermore, the FSL-1 conjugates afforded a more balanced TH1/TH2 immune response than the alum-adjuvanted group, suggesting that this combination vaccine represents a promising candidate for the prevention of GAS diseases. Thus, we established a conjugation platform that allows for the production of defined, site-specific antigen-adjuvant conjugates, which maintain the native three-dimensional structure of antigens and can be potentially applied to a variety of protein antigens.

Structural basis of transmembrane coupling of the HIV-1 envelope glycoprotein

The prefusion conformation of HIV-1 envelope protein (Env) is recognized by most broadly neutralizing antibodies (bnAbs). Studies showed that alterations of its membrane-related components, including the transmembrane domain (TMD) and cytoplasmic tail (CT), can reshape the antigenic structure of the Env ectodomain. Using nuclear magnetic resonance (NMR) spectroscopy, we determine the structure of an Env segment encompassing the TMD and a large portion of the CT in bicelles. The structure reveals that the CT folds into amphipathic helices that wrap around the C-terminal end of the TMD, thereby forming a support baseplate for the rest of Env. NMR dynamics measurements provide evidences of dynamic coupling across the TMD between the ectodomain and CT. Pseudovirus-based neutralization assays suggest that CT-TMD interaction preferentially affects antigenic structure near the apex of the Env trimer. These results explain why the CT can modulate the Env antigenic properties and may facilitate HIV-1 Env-based vaccine design.