Neutralizing Monoclonal Anti-SARS-CoV-2 Antibodies Isolated from Immunized Rabbits Define Novel Vulnerable Spike-Protein Epitope

Monoclonal antibodies represent an important avenue for COVID-19 therapy and are routinely used for rapid and accessible diagnosis of SARS-CoV-2 infection. The recent emergence of SARS-CoV-2 genetic variants emphasized the need to enlarge the repertoire of antibodies that target diverse epitopes, the combination of which may improve immune-diagnostics, augment the efficiency of the immunotherapy and prevent selection of escape-mutants. Antigen-specific controlled immunization of experimental animals may elicit antibody repertoires that significantly differ from those generated in the context of the immune response mounted in the course of disease. Accordingly, rabbits were immunized by several recombinant antigens representing distinct domains of the viral spike protein and monoclonal antibodies were isolated from single cells obtained by cell sorting. Characterization of a panel of successfully isolated anti-receptor binding domain (RBD) and anti-N-terminal domain (NTD) antibodies demonstrated that they exhibit high specificity and affinity profiles. Anti-RBD antibodies revealing significant neutralizing potency against SARS-CoV-2 in vitro were found to target at least three distinct epitopes. Epitope mapping established that two of these antibodies recognized a novel epitope located on the surface of the RBD. We suggest that the antibodies isolated in this study are useful for designing SARS-CoV-2 diagnosis and therapy approaches.

BEES AND WASPS VENOM TOXINS, ITS IMMUNE-ALLERGIC RESPONSES, DIAGNOSIS AND THERAPEUTICS

Present article explains insect toxins, its immune allergic, pharmaceutical and therapeutic effects. Insect venom glands generate enzymatic and non-enzymatic toxins and are inflicted by the stings. Insect’s envenomation are highly painful, inflamed and life-threatening. It causes breathing difficulties, bronchospasm, hypotension and arrhythmia, cardiopulmonary problems, and imposes allergic reactions. Wasp venom toxins generate strong T-cell responses in hypersensitivity patients and stimulate the production of IgE antibody molecules. Massive envenomations causes the death of victims due to the toxic effects of the venom toxins if clinical treatment is delayed. This article also emphasizes the role of natural and recombinant toxins for the development of highly sensitive immune-assays for diagnosis of allergen-specific tolerance, its early and delayed effects in patients to avoid fatal anaphylactic reactions. It also directs about the essentiality of immune diagnostics, vaccines and antiserum therapy in high population density regions where incidences of wasp and bee envenomations are more frequently occur. Venom immunotherapy can restore normal immunity against venom allergens and may also provide lifetime tolerance against venoms. This article highlights the major effects of insect venom allergens, its diagnosis and venom immunotherapy.

The FISH VENOM TOXINS: NATURAL SOURCE OF PHARMACEUTICALS AND THERAPEUTIC AGENTS “PHARMACEUTICAL AND THERAPEUTIC USES OF FISH VENOM TOXINS

The present review article explains fish toxins from different species with their pharmaceutical and therapeutic uses. Fish stinging is a major problem in coastal areas as it exerts severe toxic effects mainly in fishermen, locals, and tourists. Fish toxins cause severe pain that radiates up in the limbs and regional lymphatics. These also impose venular stasis, hemorrhage and make changes in the arteriolar wall diameter. Fish toxins target ion-channels, ligand-gated channels and G-protein coupled receptors present in body cells and obstructs their physiological and metabolic functions. They affect molecules that participate in signaling pathways, and cause hemolytic, cardiovascular, and make obstruction in nerve function and smooth muscle contraction. For quick neutralization, fish venom-induced effects in victim’s toxin-specific antibodies are used. These quickly provide relief from pain, minimize the symptoms, and stop the immediate inflammatory reaction. Fish venom toxins are of wider biomedical applications and can be used for the preparation of immune diagnostics, bio-pesticides, anticancer agents, and analgesics by using its biological information.

DIAGNOSTIC VALUE OF CERULOPLASMIN IN SYSTEMIC SCLERODERMA

Objective of study: refining immune diagnostics of systemic scleroderma through determining ceruloplasmin antibodies, its amount and enzymatic activity, as well as control of effectiveness of therapy with ceruloplasmin-based immobilized magnetocontrollable immunosorbents.Materials and methods. 30 apparently healthy individuals and 68 patients with systemic scleroderma were examined. The study included patients with referral diagnosis of systemic scleroderma who signed an informed consent. The study was performed in accordance with the principles of World Medical Association Declaration of Helsinki rev. 2013 (ACR/EULAR). All participants had their blood tested with the method of immunoenzymatic determination of antibodies to ceruloplasmin upon admission to hospital and prior to discharge.Results. It was established that patients with systemic scleroderma show reduced oxidase activity of ceruloplasmin, increased ceruloplasmin levels, as well as elevated antibodies to ceruloplasmin compared with the control group. A link between the amount of antibodies to the studied enzyme, and the activity, nature, course and stage of the disease was established. It was found that there is a reliable negative correlation between the level of ceruloplasmin antibodies, and the amount of RBCs, the hemoglobin level. For the first time a complex assessment of three parameters was employed, the parameters being the enzymatic activity, ceruloplasmin amount, and antibodies to ceruloplasmin. It was established that autoantibodies to ceruloplasmin are more often found in systemic scleroderma patients who show a high disease activity, subacute course with involvement of the liver, lungs, and with anemia. It was found that antibodies to ceruloplasmin are detected at early stages of systemic scleroderma development and can be used in timely diagnosis of the condition. It was shown that the change of parameters under study over time can serve as a basis on which to evaluate the effectiveness of administered therapy.Conclusion. Decreased enzymatic activity of ceruloplasmin, its elevated amount and increased antibodies to ceruloplasmin can be taken as additional diagnostic tools in evaluation of systemic scleroderma activity. These parameters promote a more accurate assessment of the disease activity and of the nature of the pathologic process; they can serve as an indication of a variety of clinical forms of the disease. Employing these parameters for monitoring of administered therapy in hospital settings permits a more accurate assessment of its effectiveness and making adjustments. Studying ceruloplasmin antibody formation, amount of ceruloplasmin and its biochemical activity extends the existing concept of rheumatic disease pathogeny, outlines a way forward for further research and reflects the involvement of antioxidant system in immune disorders.

Engineering high-affinity PD-1 variants for optimized immunotherapy and immuno-PET imaging

Signaling through the immune checkpoint programmed cell death protein-1 (PD-1) enables tumor progression by dampening antitumor immune responses. Therapeutic blockade of the signaling axis between PD-1 and its ligand programmed cell death ligand-1 (PD-L1) with monoclonal antibodies has shown remarkable clinical success in the treatment of cancer. However, antibodies have inherent limitations that can curtail their efficacy in this setting, including poor tissue/tumor penetrance and detrimental Fc-effector functions that deplete immune cells. To determine if PD-1:PD-L1–directed immunotherapy could be improved with smaller, nonantibody therapeutics, we used directed evolution by yeast-surface display to engineer the PD-1 ectodomain as a high-affinity (110 pM) competitive antagonist of PD-L1. In contrast to anti–PD-L1 monoclonal antibodies, high-affinity PD-1 demonstrated superior tumor penetration without inducing depletion of peripheral effector T cells. Consistent with these advantages, in syngeneic CT26 tumor models, high-affinity PD-1 was effective in treating both small (50 mm3) and large tumors (150 mm3), whereas the activity of anti–PD-L1 antibodies was completely abrogated against large tumors. Furthermore, we found that high-affinity PD-1 could be radiolabeled and applied as a PET imaging tracer to efficiently distinguish between PD-L1–positive and PD-L1–negative tumors in living mice, providing an alternative to invasive biopsy and histological analysis. These results thus highlight the favorable pharmacology of small, nonantibody therapeutics for enhanced cancer immunotherapy and immune diagnostics.

Different types of autoantibodies in rheumatic diseases and methods of their determination

Rheumatic diseases are a group of chronic disorders with varied and frequently unexplained autoimmune etiology. They results from an immune response targeted against own antigens in the autoimmune process. Arising autoantibodies bind to the autoantigen, ultimately leading to cell and tissue damage. Rheumatic diseases are characterized by the presence of antibodies exhibiting a specific antigenic activity which is useful for making the correct diagnosis. There is a known correlation between the certain autoantibodies, so-called marker autoantibodies, and specific clinical findings. Autoantibodies from this group have a high diagnostic and prognostic value. It must be emphasized that the detection of antibody in the blood serum is not in itself sufficient for diagnosis a disease, if no clinical symptoms are present. A major role in the immune diagnostics of rheumatic diseases is played by serological tests, primarily the indirect immunofluorescence assay, the last one being recognized as a gold standard in antinuclear antibodies detection. This thesis contains a description of different types of antibodies found in rheumatic disorders, an evaluation of their clinical usefulness and immunodiagnostic methods of their determination.