ABSTRACT
Monitoring of the proportion of immune individuals and the effectiveness of vaccination in a population involves evaluation of several important parameters, including the level of virus-neutralising antibodies. In order to combat the COVID-19 pandemic, it is essential to develop approaches to detecting SARS-CoV-2 neutralising antibodies by safe, simple and rapid methods that do not require live viruses. To develop a test system for enzyme-linked immunosorbent assay (ELISA) that detects potential neutralising antibodies, it is necessary to obtain a highly purified recombinant receptor-binding domain (RBD) of the spike (S) protein with high avidity for specific antibodies. The aim of the study was to obtain and characterise a SARSCoV-2 S-protein RBD homodimer and a recombinant RBD-expressing cell line, as well as to create an ELISA system for detecting potential neutralising antibodies. Material(s) and Method(s): the genetic construct was designed in silico. To generate a stable producer cell line, the authors transfected CHO-S cells, subjected them to antibiotic pressure, and selected the optimal clone. To isolate monomeric and homodimeric RBD forms, the authors purified the recombinant RBD by chromatographic methods. Further, they analysed the activity of the RBD forms by Western blotting, bio-layer interferometry, and indirect ELISA. The analysis involved monoclonal antibodies GamXRH19, GamP2C5, and h6g3, as well as serum samples from volunteers vaccinated with Gam-COVID-Vac (Sputnik V) and unvaccinated ones. Result(s): the authors produced the CHO-S cell line for stable expression of the recombinant SARS-CoV-2 S-protein RBD. The study demonstrated the recombinant RBD's ability to homodimerise after fed-batch cultivation of the cell line for more than 7 days due to the presence of unpaired cysteines. The purified recombinant RBD yield from culture broth was 30-50 mg/L. Monomeric and homodimeric RBD forms were separated using gel-filtration chromatography and characterised by their ability to interact with specific monoclonal antibodies, as well as with serum samples from vaccinated volunteers. The homodimeric recombinant RBD showed increased avidity for both monoclonal and immune sera antibodies. Conclusion(s): the homodimeric recombinant RBD may be more preferable for the analysis of levels of antibodies to the receptor-binding domain of the SARS-CoV-2 S protein.Copyright © 2023 Authors. All rights reserved.
ABSTRACT
COVID-19, caused by the novel SARS-CoV-2 virus, poses major challenges for global public health. The detection of antibodies in blood serum is one of the important methods for diagnostics of COVID-19 patients. The main aim was to study the dynamics of the appearance of neutralizing antibodies and antibodies to the SARS-CoV-2 proteins in COVID-19 patients sera. Material and methods. The blood sera of four groups of people were studied: "intact" donors (blood sera were collected in 2016-2019);patients with a laboratory-confirmed diagnosis of acute respiratory viral infection;patients with influenza (antibodies to the influenza virus have been identified) and patients with a PCR confirmed diagnosis of COVID-19. Blood sera were analyzed in ELISA with commercial kits for detection of IgG to SARS-CoV-2 (N, S) proteins and total antibodies to RBD of protein S and in neutralization test (NT). Results and discussion. Antibodies to SARS-CoV-2 were not detected in paired blood sera of people from groups 1-3 by ELISA and NT. At the time of hospitalization of patients with COVID-19 in the sera of 12 (19%) patients antibodies to SARS-CoV-2 were absent when they were determined by NT and ELISA. In blood sera taken 4-9 days after hospitalization, neutralizing antibodies and antibodies to at least one viral protein were detected in ELISA. Conclusion. At the time of hospitalization, the overwhelming majority of patients had a humoral immune response to the SARS-CoV-2. In the dynamics of observation, the levels of antibodies to SARS-CoV-2 proteins increased, to a greater extent to RBD.Copyright © 2022 Geotar Media Publishing Group
ABSTRACT
Given the actual risk of poliomyelitis outbreaks in the region due to poliovirus derived from the Sabin vaccine or the importation of wild poliovirus, the Latin American Society of Pediatric Infectious Diseases commissioned an ad hoc group of experts from the institution's Vaccines and Biologicals Committee, to draft an official position paper on the urgent need to increase immunization levels against the disease in the region and incorporate inactivated polio vaccine exclusive schedules in all national immunization programs. This publication discusses the main conclusions and recommendations generated as a result of such activity.Copyright © 2022, Sociedad Chilena de Infectologia. All rights reserved.
ABSTRACT
Background: One of the efforts to control SARS-CoV-2 infection in health workers is vaccination. In this study, the levels of SARS-CoV-2 neutralizing antibody (nAb) in health workers were measured with Ichroma and iFlash. Method(s): This study applied an observational analytic design with a prospective cohort and was conducted at Dr. Soetomo Regional Public Hospital, Surabaya, from January to November 2021. The population of this study included a total of 75 health workers after taking the second dose of the SARS-CoV-2 (Sinovac) vaccine. The Covid-19 NAb levels of the population were tested with Ichroma and iFlash on day 0 before vaccination, as well as days 14 and 28, and months 3 and 6 after vaccination. Result(s): The Friedman test indicated a significant difference in NAb levels according to the iFlash test on day 14, day 28, month 3, and month 6 compared to those before vaccination (p < 0.05). The Wilcoxon test revealed a significant difference in NAb levels on day 14, day 28, month 3, and month 6. The results of the Cochran test showed a significant difference in the positivity of NAb according to the Ichroma test on day 14, day 28, month 3, and month 6 compared to those before vaccination (p < 0.05). McNemar's test demonstrated that the COI at month 3 was not significantly different from that before vaccination;The COI at month 6 was not significantly different from those at days 14 and 28. The results of the Pearson correlation test and Bland-Altman plot indicated a moderate correlation between Ichroma and iFlash (r = 0.592, p = 0.002). Conclusion(s): Neutralizing antibodies for Covid-19 were formed after day 14 and started to increase on day 28 and started to decrease in months 3 and 6. The levels of NAb for Covid-19 were measured with Ichroma and iFlash in roughly the same pattern and had a moderate positive correlation.Copyright © 2023 Phcogj.Com.
ABSTRACT
Various antibody therapeutics has been developed for the treatment and suppression of the 2019 outbreak of novel coronavirusSARS-CoV-2infection. A major limitation in the development DDS of SARS-CoV-2 neutralizing antibodies is the occurrence and spread of escape variants that have mutations in the spike glycoprotein. The coronaviruses are carried by various wild animals, domestic animals, and pets, and there have been cases of Severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus transmission from animals to people, resulting in a large spread of infection in people. There is also a possibility that cross-species transmission of SARS-CoV-2 may occur in the future. Considering these factors, the development of antibody therapeutics with broad cross-reactivity against SARS-CoV-2 variants and other coronaviruses is required.Copyright © 2022, Japan Society of Drug Delivery System. All rights reserved.
ABSTRACT
The genetic evolution of SARS-CoV-2 began in February 2020, with G614 spike protein strains superseding D614 strains globally. Since then with each subsequent mutations, the SARS-CoV-2 variants of concern, namely Alpha, Beta, Gamma, Delta and Omicron, superseded the previous one to become the dominant strain during the pandemic. By the end of November 2022, the Omicron variant and its descendent lineages account for 99.9% of sequences reported globally. All five VOCs have mutations located in the RBD of the spike protein, resulting in increased affinity of the spike protein to the ACE2 receptors resulting in enhanced viral attachment and its subsequent entry into the host cells. In vitro studies showed the mutations in spike protein help increase the viral fitness, enhancing both transmissibility and replication. In general, Alpha, Beta, Gamma, and Delta variants, were reported with higher transmissibility of 43-90%, around 50%, 170-240%, or 130-170% than their co-circulating VOCs, respectively. The Omicron however was found to be 2.38 times and 3.20 times more transmissible than Delta among the fully-vaccinated and booster-vaccinated households. Even the SARS-Cov-2 Omicron subvariants appear to be inherently more transmissible than the ones before. With the broader distribution, enhanced evasion, and improved transmissibility, SARS-CoV-2 variants infection cause severe diseases due to immune escape from host immunity and faster replication. Reports have shown that each subsequent VOC, except Omicron, cause increased disease severity compared with those infected with other circulating variants. The Omicron variant infection however, appears to be largely associated with a lower risk of hospitalisation, ICU admission, mechanical ventilation, and even a shorter length of hospital stay. It has been shown that the relatively much slower replication of the Omicron variants in the lung, resulted in a less severe disease.Copyright © 2022, Malaysian Society of Pathologists. All rights reserved.
ABSTRACT
The year 2020 was the most challenging period due to the havoc caused by the outbreak of novel coronavirus SARS-CoV-2. Scientists and researchers all around the world have endeav-ored every possible approach to find solutions in context to therapeutics and vaccines to control the spread of this life-threatening virus. The acceleration instigated by the outbreak of SARS-CoV-2 and its mutated strains has leveraged the use of numerous platform technologies for the development of vaccines against this unfathomable disease. Vaccines could play an important role in miti-gating the effects of COVID-19 and reducing the ongoing health crisis. Various innovative plat-forms like proteins, nucleic acids, viruses, and viral vectors have been exploited to fabricate vaccines depicting almost 90% of efficacy like BNT162b2, AZD1222, Ad5-nCoV, etc. Some of these vaccines are multipotent and have shown potent activity against newly emerged malicious strains of SARS-CoV-2 like B.1.351 and B.1.1.7. In this review article, we have gathered key findings from various sources of recently popularized vaccine candidates, which will provide an overview of potential vaccine candidates against this virus and will help the researchers to investi-gate possible ways to annihilate this menace and design new moieties.Copyright © 2022 Bentham Science Publishers.
ABSTRACT
COVID-19 is an acute respiratory infectious disease caused by 2019-nCoV, which has become a major global public health event and a serious threat to human health. So far, specific antiviral drugs, safe and effective vaccines for 2019-nCoV are still under development, so there is an urgent need to find alternative strategies for the treatment of COVID-19. Convalescent plasma(CP) contains high titer neutralizing antibodies from patients recovering from infectious diseases, which has been used in the treatment of major infectious diseases such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), and achieved satisfactory clinical results. Therefore, CP from COVID-19 patient is a meaningful choice for the treatment of severe or life-threatening COVID-19 patients, but its potential risks need to be studied. This review focuses on the clinical mechanism, collection points, clinical application and potential benefits and risks of clinical treatment of CP from COVID-19 patients, which will provide reference for the clinical application of CP from COVID-19 patients.Copyright © 2021 Chinese Medical Association
ABSTRACT
In November 2020, the Armed Forces of the Russian Federation began mass immunisation of the personnel with Gam-COVID-Vac (Sputnik V), the first Russia vaccine against the new coronavirus infection (COVID-19). Thus, it became necessary to assess post-vaccination antibody levels and the duration and intensity of humoral immunity to COVID-19. The aim of the study was to investigate the immunogenicity and efficacy of Gam-COVID-Vac in military medical staff after vaccination. Material(s) and Method(s): the authors determined the presence of specific antibodies in the serum of individuals immunised with Gam-COVID-Vac (477 volunteers) and COVID-19 convalescents (73 patients), using virus neutralisation (VN), enzyme-linked immunosorbent assay (ELISA) with reagent kits by several manufacturers, and immunoblotting. The results of the study were evaluated using analysis of variance. Result(s): VN detected virus neutralising antibodies in 90.7% of vaccinated subjects;ELISA, in 95.4%. Both VN and ELISA showed lower antibody levels in the vaccinated over 50 years of age. ELISA demonstrated a significantly higher concentration of anti-SARS-CoV-2 spike IgG in the Gam-COVID-Vac group than in the COVID-19 convalescent group. The correlation between antibody detection results by VN and ELISA was the strongest when the authors used their experimental reagent kit for quantitative detection of virus neutralising antibodies by competitive ELISA with the recombinant human ACE2 receptor. Having analysed the time course of neutralising antibody titres, the authors noted a significant, more than two-fold decrease in geometric means of the titres three months after administration of the second vaccine component. Conclusion(s): the subjects vaccinated with Gam-COVID-Vac gain effective humoral immunity to COVID-19. The decrease in titres indicates the need for revaccination in 6 months.Copyright © 2023 Safety and Risk of Pharmacotherapy. All rights reserved.
ABSTRACT
Comparative analysis of antiviral protective mechanisms in protozoa and RNA interference of multicellular organisms has revealed their similarity, also providing a clue to understanding the adaptive immunity. In this article, we present the latest evidence on the importance of RNA-guided gene regulation in human antiviral defense. The role of neutralizing antibodies and interferon system in viral invasion is considered. The new concept has been introduced, i.e., antiviral protection of any living organism is based on the intracellular RNA-guided mechanisms. Simple and effective defense against viruses is that spacer segment of the viral DNA is inserted into the cellular chromosomes. Upon re-infection, the RNA transcript of the spacer directs nuclease enzymes against the foreign genome. This is a really adaptive immune defense that any cell potentially possesses. In humans, the interferon system provides an additional tool for early suppression of viral infections which shifts the cells to the alert regimen, thus preventing further spread of infection. The main task of the human central immune system is to maintain integrity and combat foreign organisms. Accordingly, a suitable index of acquired antiviral immunity should be a presence of specific spacer markers in DNA samples from reconvalescent persons, rather than detection of neutralizing antibodies, B and T memory cells. This article is addressed primarily to general medical community, and its practical conclusions are as follows: 1. Presence or absence of specific antibodies to SARS-CoV-2 is not a prognostic sign of the disease. Detection of specific antibodies in blood simply reflects the fact that the person has contacted with the viral agent. Absence of antibodies does not mean a lack of such contact, and the persons with high titers of specific antibodies are not protected from re-infection with SARS-CoV-2. 2. PCR testing: The PCR results may remain "false positive" in those subjects who have had COVID-19, if the genetic material is taken from the site of initial virus contraction (mainly, nasopharynx). In our opinion, negative PCR tests for COVID-19 in blood plasma and urine will be a more correct index for the absence of the disease, even with positive PCR tests from the nasopharyngeal samples. 3. It is necessary to draw attention of general practitioners to potential usage of retinol in prevention and treatment of COVID-19, given the importance of RLR receptors in recognition of viral RNAs and positive experience of vitamin A administration in measles, another dangerous viral disease. Copyright © 2022, SPb RAACI.