Coronavirus XBB.1.5 as an Indicator of the Long-Term Continuation of the Covid-19 pandemic. What Next for Vaccination?

The article discusses the properties of the pandemic strain XBB.1.5 S protein in comparison with the 1918 and 2009 pandemic strains hemagglutinin H1. The S-protein XBB.1.5 already contains more than 40 mutations realized by substituting different amino acids through single and dinucleotide substitutions, deletions and the use of predominantly transversions. The variability of H1N1 influenza virus hemagglutinin is associated with single nucleotide substitutions at a constant length. Conditional extrapolation of influenza virus hemagglutinin variability data on coronavirus S-protein sizes suggests that new pandemic strains will emerge in the next 2-3 years, avoiding the immune defense formed by vaccination against the strains preceding them. The inability to create through the adaptive immune system a long-term immunity to pandemic coronaviruses, as well as to other respiratory viruses with a short incubation cycle, puts on the agenda the need to find new vaccine designs that provide a combination of long-term adaptive and trained immunity. The problem in the search for such vaccines is associated with the regulation of the activity of the innate immune system and ensuring the stability of trained immunity. © 2023, Numikom. All rights reserved.

Synergistic effect of elevated glucose levels with SARS-CoV-2 spike protein induced NOX-dependent ROS production in endothelial cells.

BACKGROUND: Diabetic patients infected with coronavirus disease 2019 (COVID-19) often have a higher probability of organ failure and mortality. The potential cellular mechanisms through which blood glucose exacerbates tissue damage due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is still unclear. METHODS AND RESULTS: We cultured endothelial cells within differing glucose mediums with an increasing concentration gradient of SARS-CoV-2 Spike protein (S protein). S protein can cause the reduction of ACE2 and TMPRSS2, and activation of NOX2 and NOX4. A high glucose medium was shown to aggravate the decrease of ACE2 and activation of NOX2 and NOX4 in cultured cells, but had no effect on TMPRSS2. S protein mediated activation of the ACE2-NOX axis induced oxidative stress and apoptosis within endothelial cells, leading to cellular dysfunction via the reduction of NO and tight junction proteins which may collectively be exacerbated by elevated glucose. In addition, the glucose variability model demonstrated activation of the ACE2-NOX axis in a similar manner observed in the high glucose model in vitro. CONCLUSIONS: Our present study provides evidence for a mechanism through which hyperglycemia aggravates endothelial cell injury resulting from S protein mediated activation of the ACE2-NOX axis. Our research thus highlights the importance of strict monitoring and control of blood glucose levels within the context of COVID-19 treatment to potentially improve clinical outcomes.

The Stability Study of Electrochemical Aptasensor to Detect SARS-CoV-2 Spike Protein and Its Application for Clinical Samples of Nasopharyngeal Swab

The stability characteristics associated with the shelf life of a biosensor are rarely investigated, however, they are important factors for real applications. Stability is the variation in the detection signal over a long period of storage. This study aims to determine the effect of storage time on the stability of SARS-CoV-2 receptor binding domain (RBD) spike protein aptamers related to shelf life and the performance of an electrochemical aptasensor on clinical samples. The research method includes a stability study conducted using the accelerated stability method based on the Arrhenius equation at three variations of temperature and storage time. The electrochemical aptasensor's performance was evaluated on clinical samples of 32 nasopharyngeal swabs at biosafety level 3 and its potential on clinical saliva samples. The results indicated that the developed electrochemical aptasensor was stable for ± 15 days with a shelf life of 18, 17 and 16 days, respectively, at 25, 40 and 50 °C. This electrochemical aptasensor has the potential to be a Point of Care (POC) device for the clinical detection of SARS-CoV-2 because it can be tested on clinical samples of nasopharyngeal swabs and the results show its potential application to detect in clinical saliva samples. © Arum Kurnia Sari et al.

Conserved longitudinal alterations of anti-S-protein IgG subclasses in disease progression in initial ancestral Wuhan and vaccine breakthrough Delta infections.

Introduction: COVID-19 has a wide disease spectrum ranging from asymptomatic to severe. While humoral immune responses are critical in preventing infection, the immune mechanisms leading to severe disease, and the identification of biomarkers of disease progression and/or resolution of the infection remains to be determined. Methods: Plasma samples were obtained from infections during the initial wave of ancestral wildtype SARS-CoV-2 and from vaccine breakthrough infections during the wave of Delta variant, up to six months post infection. The spike-specific antibody profiles were compared across different severity groups and timepoints. Results: We found an association between spike-specific IgM, IgA and IgG and disease severity in unvaccinated infected individuals. In addition to strong IgG1 and IgG3 response, patients with severe disease develop a robust IgG2 and IgG4 response. A comparison of the ratio of IgG1 and IgG3 to IgG2 and IgG4 showed that disease progression is associated with a smaller ratio in both the initial wave of WT and the vaccine breakthrough Delta infections. Time-course analysis revealed that smaller (IgG1 and IgG3)/(IgG2 and IgG4) ratio is associated with disease progression, while the reverse associates with clinical recovery. Discussion: While each IgG subclass is associated with disease severity, the balance within the four IgG subclasses may affect disease outcome. Acute disease progression or infection resolution is associated with a specific immunological phenotype that is conserved in both the initial wave of WT and the vaccine breakthrough Delta infections.

A substrate for a cell free in vitro assay system to screen drugs targeting trypsin like protease-based cleavage of SARS-CoV-2 spike glycoprotein and viral entry.

Host proteases trypsin and trypsin-like proteases have been reported to facilitate the entry of coronavirus SARS-CoV-2 in its host cells. These protease enzymes cleave the viral surface glycoprotein, spike, leading to successful cell surface receptor attachment, fusion and entry of the virus in its host cell. The spike protein has protease cleavage sites between the two domains S1 and S2. Since the cleavage site is recognized by the host proteases, it can be a potential antiviral therapeutic target. Trypsin-like proteases play an important role in virus infectivity and the property of spike protein cleavage by trypsin and trypsin-like proteases can be used to design assays for screening of antiviral candidates against spike protein cleavage. Here, we have documented the development of a proof-of-concept assay system for screening drugs against trypsin/trypsin-like proteases that cleave spike protein between its S1 and S2 domains. The assay system developed uses a fusion substrate protein containing a NanoLuc luciferase reporter protein, the protease cleavage site between S1 and S2 domains of SARS-CoV-2 spike protein and a cellulose binding domain. The substrate protein can be immobilized on cellulose via the cellulose binding domain of the substrate. When trypsin and trypsin-like proteases cleave the substrate, the cellulose binding domain remain bound to the cellulose and the reporter protein is dislodged. Reporter assay using the released reporter protein is the read out of the protease activity. We have demonstrated the proof-of-concept using multiple proteases like trypsin, TMPRSS2, furin, cathepsin B, human airway trypsin and cathepsin L. A significant increment in fold change was observed with increasing enzyme concentration and incubation time. Introduction of increasing amounts of enzyme inhibitors in the reaction reduced the luminescent signal, thus validating the assay. Furthermore, we used SDS-PAGE and immunoblot analyses to study the cleavage band pattern and re-confirm the cleavage for enzymes tested in the assay. Taken together, we have tested an in-vitro assay system using the proposed substrate for screening drugs against trypsin like protease-based cleavage of SARS-CoV-2 spike glycoprotein. The assay system can also be potentially used for antiviral drug screening against any other enzyme that might cleave the used cleavage site.

Waning of specific antibodies against Delta and Omicron variants five months after a third dose of BNT162b2 SARS-CoV-2 vaccine in elderly individuals.

The emergence of new SARS-CoV-2 variants, such as the more transmissible Delta and Omicron variants, has raised concerns on efficacy of the COVID-19 vaccines. Here, we examined the waning of antibody responses against different variants following primary and booster vaccination. We found that antibody responses against variants were low following primary vaccination. The antibody response against Omicron was almost non-existent. Efficient boosting of antibody response against all variants, including Omicron, was observed following a third dose. The antibody response against the variants tested was significantly higher at one month following booster vaccination, compared with two months following primary vaccination, for all individuals, including the low antibody responders identified at two months following primary vaccination. The antibody response, for all variants tested, was significantly higher at four months post booster than at five months post primary vaccination, and the proportion of low responders remained low (6-11%). However, there was significant waning of antibody response in more than 95% of individuals at four months, compared to one month following booster. We also observed a robust memory B cell response following booster, which remained higher at four months post booster than prior to booster. However, the memory B cell responses were on the decline for 50% of individuals at four months following booster. Similarly, while the T cell response is sustained, at cohort level, at four months post booster, a substantial proportion of individuals (18.8 - 53.8%) exhibited T cell response at four months post booster that has waned to levels below their corresponding levels before booster. The findings show an efficient induction of immune response against SARS-CoV-2 variants following booster vaccination. However, the induced immunity by the third BNT162b2 vaccine dose was transient. The findings suggest that elderly individuals may require a fourth dose to provide protection against SARS-CoV-2.

SARS-CoV-2 N Protein Triggers Acute Lung Injury via Modulating Macrophage Activation and Infiltration in in vitro and in vivo.

Background: SARS-CoV-2-induced acute lung injury but its nucleocapsid (N) and/or Spike (S) protein involvements in the disease pathology remain elusive. Methods: In vitro, the cultured THP-1 macrophages were stimulated with alive SARS-CoV-2 virus at different loading dose, N protein or S protein with/without TICAM2-siRNA, TIRAP-siRNA or MyD88-siRNA. The TICAM2, TIRAP and MyD88 expression in the THP-1 cells after N protein stimulation were determined. In vivo, naïve mice or mice with depletion macrophages were injected with N protein or dead SARS-CoV-2. The macrophages in the lung were analyzed with flow cytometry, and lung sections were stained with H&E or immunohistochemistry. Culture supernatants and serum were harvested for cytokines measurements with cytometric bead array. Results: Alive SARS-CoV-2 virus or N protein but not S protein induced high cytokine releases from macrophages in a time or virus loading dependent manner. MyD88 and TIRAP but not TICAM2 were highly involved in macrophage activation triggered by N protein whilst both inhibited with siRNA decreased inflammatory responses. Moreover, N protein and dead SARS-CoV-2 caused systemic inflammation, macrophage accumulation and acute lung injury in mice. Macrophage depletion in mice decreased cytokines in response to N protein. Conclusion: SARS-CoV-2 and its N protein but not S protein induced acute lung injury and systemic inflammation, which was closely related to macrophage activation, infiltration and release cytokines.

Monoclonal antibody designed for SARS-nCoV-2 spike protein of receptor binding domain on antigenic targeted epitopes for inhibition to prevent viral entry.

SARS, or severe acute respiratory syndrome, is caused by a novel coronavirus (COVID-19). This situation has compelled many pharmaceutical R&D companies and public health research sectors to focus their efforts on developing effective therapeutics. SARS-nCoV-2 was chosen as a protein spike to targeted monoclonal antibodies and therapeutics for prevention and treatment. Deep mutational scanning created a monoclonal antibody to characterize the effects of mutations in a variable antibody fragment based on its expression levels, specificity, stability, and affinity for specific antigenic conserved epitopes to the Spike-S-Receptor Binding Domain (RBD). Improved contacts between Fv light and heavy chains and the targeted antigens of RBD could result in a highly potent neutralizing antibody (NAbs) response as well as cross-protection against other SARS-nCoV-2 strains. It undergoes multipoint core mutations that combine enhancing mutations, resulting in increased binding affinity and significantly increased stability between RBD and antibody. In addition, we improved. Structures of variable fragment (Fv) complexed with the RBD of Spike protein were subjected to our established in-silico antibody-engineering platform to obtain enhanced binding affinity to SARS-nCoV-2 and develop ability profiling. We found that the size and three-dimensional shape of epitopes significantly impacted the activity of antibodies produced against the RBD of Spike protein. Overall, because of the conformational changes between RBD and hACE2, it prevents viral entry. As a result of this in-silico study, the designed antibody can be used as a promising therapeutic strategy to treat COVID-19.

Herbal medicines exhibit a high affinity for ACE2 in treating COVID-19.

Coronavirus Disease 2019 (COVID-19) has been an unprecedented disaster for people around the world. A point particularly worth noting is that herbal medicines have made great contributions to the prevention and treatment of COVID-19 in China. Angiotensin converting enzyme 2 (ACE2) has been identified as the critical functional receptor for SARS-CoV-2. It can bind to the receptor-binding domain (RBD) of the spike protein (S protein), which is responsible for the entry of the coronavirus into host cells. Therefore, ACE2 can be regarded as an important intervention target for COVID-19. Recently, many herbal medicines have exhibited a high affinity for ACE2 in treating COVID-19. The current work summarized these herbal medicines including formulas (such as Lianhua Qingwen capsules, Xuebijing injection, Qingfei Paidu Decoction, Huashi Baidu formula, Shufeng Jiedu capsules, and Maxing Shigan decoction), single herbs including Ephedra sinica Stapf (Mahuang), Scutellariae radix (Huangqin), Lonicera japonica (Jinyinhua), and Houttuynia cordata (Yuxingcao), and active ingredients (such as ursodeoxycholic acid, glycyrrhizic acid, glycyrrhizin, salvianolic acid, quercetin, and andrographidine C), which have exhibited a high affinity for ACE2 in treating COVID-19. We hope this work may provide meaningful and useful information on further research to investigate the mechanisms of herbal medicines against SARS-CoV-2 and follow-up drug discovery.

Cholesterol and Melatonin Exert Opposite Effects on the Interaction of Model DMPC Membranes with the SARS-CoV-2 S-Protein: A SANS Study

An effect of receptor-binding domain (RBD) of SARS-CoV-2 S-protein on structural parameters of model lipid membranes presented by dimyristoylphosphatidylcholine (DMPC) systems with cholesterol and melatonin impurities is studied by small angle neutron scattering (SANS). It is shown that an increase in melatonin concentration in the lipid membrane leads to a decrease in the thickness of the lipid bilayer, while an increase in the concentration of cholesterol leads to an increase in its thickness. It is suggested that increasing the concentration of melatonin in a membrane prevents the interaction of coronaviral S-protein with a lipid membrane of a cell. In the presence of cholesterol in the system, the interaction of a lipid membrane with an active part of S-protein occurs depending on a phase state of the lipid: in the case of a gel phase, there is no changes in structural parameters, but at higher temperatures in the case of a liquid crystal phase, an addition of RBD SARS-CoV-2 to the system causes a reduce in the membrane thickness. © 2023 Wiley-VCH GmbH.

Adaptation of the infectious bronchitis virus H120 vaccine strain to Vero cell lines.

Infectious bronchitis virus (IBV) has restricted cell and tissue tropism. IBVs, except the Beaudette strain, can infect and replicate in chicken embryos, primary chicken embryo kidneys, and primary chicken kidney cells, only. The limited viral cell tropism of IBV substantially hinders in vitro cell-based research on pathogenic mechanisms and vaccine development. Herein, the parental H120 vaccine strain was serially passaged for five generations in chicken embryos, 20 passages in CK cells and 80 passages in Vero cells. This passaging yielded a Vero cell-adapted strain designated HV80. To further understand viral evolution, serial assessments of infection, replication, and transmission in Vero cells were performed for the viruses obtained every tenth passage. The ability to form syncytia and the replication efficiency significantly after the 50th passage (strain HV50). HV80 also displayed tropism extension to DF-1, BHK-21, HEK-293 T, and HeLa cells. Whole genome sequencing of viruses from every tenth generation revealed a total of 19 amino acid point mutations in the viral genome by passage 80, nine of which occurred in the S gene. The second furin cleavage site appeared in viral evolution and may be associated with cell tropism extension of HV80.

Structural insights into the effect of mutations in the spike protein of SARS-CoV-2 on the binding with human furin protein.

The SARS COV-2 and its variants are spreading around the world at an alarming speed, due to its higher transmissibility and the conformational changes caused by mutations. The resulting COVID-19 pandemic has imposed severe health consequences on human health. Several countries of the world including Pakistan have studied its genome extensively and provided productive findings. In the current study, the mCSM, DynaMut2, and I-Mutant servers were used to analyze the effect of identified mutations on the structural stability of spike protein however, the molecular docking and simulations approaches were used to evaluate the dynamics of the bonding network between the wild-type and mutant spike proteins with furin. We addressed the mutational modifications that have occurred in the spike protein of SARS-COV-2 that were found in 215 Pakistani's isolates of COVID-19 patients to study the influence of mutations on the stability of the protein and its interaction with the host cell. We found 7 single amino acid substitute mutations in various domains that reside in spike protein. The H49Y, N74K, G181V, and G446V were found in the S1 domain while the D614A, V622F, and Q677H mutations were found in the central helices of the spike protein. Based on the observation, G181V, G446V, D614A, and V622F mutants were found highly destabilizing and responsible for structural perturbation. Protein-protein docking and molecular simulation analysis with that of furin have predicted that all the mutants enhanced the binding efficiency however, the V622F mutant has greatly altered the binding capacity which is further verified by the KD value (7.1 E-14) and therefore may enhance the spike protein cleavage by Furin and increase the rate of infectivity by SARS-CoV-2. On the other hand, the total binding energy for each complex was calculated which revealed -50.57 kcal/mol for the wild type, for G181V -52.69 kcal/mol, for G446V -56.44 kcal/mol, for D614A -59.78 kcal/mol while for V622F the TBE was calculated to be -85.84 kcal/mol. Overall, the current finding shows that these mutations have increased the binding of Furin for spike protein and shows that D614A and V622F have significant effects on the binding and infectivity.

Molecular Modeling of Viral Type I Fusion Proteins: Inhibitors of Influenza Virus Hemagglutinin and the Spike Protein of Coronavirus.

The fusion of viral and cell membranes is one of the basic processes in the life cycles of viruses. A number of enveloped viruses confer fusion of the viral envelope and the cell membrane using surface viral fusion proteins. Their conformational rearrangements lead to the unification of lipid bilayers of cell membranes and viral envelopes and the formation of fusion pores through which the viral genome enters the cytoplasm of the cell. A deep understanding of all the stages of conformational transitions preceding the fusion of viral and cell membranes is necessary for the development of specific inhibitors of viral reproduction. This review systematizes knowledge about the results of molecular modeling aimed at finding and explaining the mechanisms of antiviral activity of entry inhibitors. The first section of this review describes types of viral fusion proteins and is followed by a comparison of the structural features of class I fusion proteins, namely influenza virus hemagglutinin and the S-protein of the human coronavirus.

Decreased breadth of the antibody response to the spike protein of SARS-CoV-2 after repeated vaccination.

Introduction: The rapid development of vaccines to prevent COVID-19 has raised the need to compare the capacity of different vaccines in terms of developing a protective humoral response. Previous studies have shown inconsistent results in this area, highlighting the importance of further research to evaluate the efficacy of different vaccines. Methods: This study utilized a highly sensitive and reliable flow cytometry method to measure the titers of IgG1 isotype antibodies in the blood of healthy volunteers after receiving one or two doses of various vaccines administered in Spain. The method was also used to simultaneously measure the reactivity of antibodies to the S protein of the original Wuhan strain and variants B.1.1.7 (Alpha), B.1.617.2 (Delta), and B.1.617.1 (Kappa). Results: Significant differences were observed in the titer of anti-S antibodies produced after a first dose of the vaccines ChAdOx1 nCov-19/AstraZeneca, mRNA-1273/Moderna, BNT162b2/Pfizer-BioNTech, and Ad26.COV.S/Janssen. Furthermore, a relative reduction in the reactivity of the sera with the Alpha, Delta, and Kappa variants, compared to the Wuhan strain, was observed after the second boosting immunization. Discussion: The findings of this study provide a comparison of different vaccines in terms of anti-S antibody generation and cast doubts on the convenience of repeated immunization with the same S protein sequence. The multiplexed capacity of the flow cytometry method utilized in this study allowed for a comprehensive evaluation of the efficacy of various vaccines in generating a protective humoral response. Future research could focus on the implications of these findings for the development of effective COVID-19 vaccination strategies.

Study of Humoral Immunity against Coronavirus Infection COVID-19 in Vaccinated Individuals with Vaccines Available in the Republic of Belarus (Sputnik V (Gam-COVID-Vac), RF and Sinopharm (BBIBP-CorV), PRC)

Relevance. Many countries around the world are developing effective vaccines against SARS-CoV-2. The measure of the effectiveness of the vaccination process has traditionally been antibody production. The frequency and intensity of adverse reactions is also an important factor in making a decision regarding a vaccine. This study presents the results of the evaluation of the formation of humoral immunity and the occurrence of reactions in response to the administration of Sputnik V (Gam-COVID-Vac), RF, and Sinopharm (BBIBP-CorV), PRC. Aim. Analyze immunogenicity and reactogenicity of COVID-19 vaccines used in the Republic of Belarus (Sputnik V and Sinopharm). Materials and methods. Evaluation of postvaccination immune response by enzyme immunoassay and differential enzyme immunoassay for class G immunoglobulins to S-and N-proteins SARS-CoV-2. Blood plasma of the study participants was used as biological material. Blood sampling was performed 3 times: immediately before the first vaccine dose, on day 42, and 6 months after the first vaccine dose. To evaluate the frequency and intensity of postvaccination reactions, study participants were questioned. Results. At 42 days after administration of both vaccines, antibody levels are rising, with a significantly higher quantitative IgG count for the Sputnik V vaccine. This trend is also observed 6 months after the first dose of both vaccines, both among those previously infected with SARS-CoV-2 and those without a history of COVID-19. The comparison of Sputnik V and Sinopharm vaccine groups in terms of IgG (BAU/ml) levels to S-and N-proteins revealed a statistically significant difference in IgG levels to S-protein: the Sputnik V vaccine group had significantly higher IgG levels to S-protein than the Sinopharm vaccine group (p = 0.0000196). The incidence of adverse reactions in this study was 45%. All reactions noted were mild to moderate in severity. The most common were soreness and redness at the injection site, elevated body temperature, and a combination of several reactions. The increased body temperature after vaccination was more common among those vaccinated with the Sputnik V vaccine. Conclusion. Compared to Sinopharm, Sputnik V vaccine produces higher antibody level. Adverse reactions were observed in both vaccinated groups. However, significant statistical differences were found with regard to fever in the Sputnik V vaccine group, which occurred more frequently. © 2023, Numikom. All rights reserved.

Antibodies to the receptor-binding domain of the SARS-Cov-2 spike protein: association with age, pneumonia, duration of the period after COVID-19.

Despite the rapid accumulation of facts about the humoral immune response in COVID-19, there are still no evidence-based answers to questions about the factors influencing the level and duration of the detection period of antibodies to SARS-CoV-2 in the blood. Objective(s): To assess the prevalence, clinical and demographic associations of IgG antibodies to RBD of the SARSCoV-2 spike protein at different times after COVID-19. Materials and methods. Residents of the Altai region of Russia, Caucasians aged 20-93 years, who had COVID-19 from May 2020 to February 2021 (n = 314), took part in a onetime observational study. The level of antibodies in the blood was measured by enzyme-linked immunosorbent assay 1-14 months after the onset of the clinical manifestation of CO-VID-19. Results. Anti-RBD IgG antibodies of the SARS-CoV-2 spike protein were detected in 86.9% of the study participants. The dependence of the antibody titer on the duration of the period after COVID-19 was not revealed. The antibody titer was positively correlated with the complication of CO-VID-19 pneumonia and the volume of lung tissue lesions. The presence of pneumonia COVID-19 and the volume of lung tissue lesions are positively associated with age. Age positively correlated with antibody titer regardless of the pneumonia COVID-19 in the anamnesis. Conclusion. IgG antibodies to RBD of the SARS-CoV-2 spike protein are present in most of the COVID-19 patients. The titer of these antibodies in adults depends on age, complications of pneumonia COVID-19, and probably persists up to 14 months after the first symptoms of infection appear.Copyright © 2022 Interregional public organization Association of infectious disease specialists of Saint-Petersburg and Leningrad region (IPO AIDSSPbR). All rights reserved.

Antibodies to the receptor-binding domain of the SARS-Cov-2 spike protein: association with age, pneumonia, duration of the period after COVID-19.

Despite the rapid accumulation of facts about the humoral immune response in COVID-19, there are still no evidence-based answers to questions about the factors influencing the level and duration of the detection period of antibodies to SARS-CoV-2 in the blood. Objective(s): To assess the prevalence, clinical and demographic associations of IgG antibodies to RBD of the SARSCoV-2 spike protein at different times after COVID-19. Materials and methods. Residents of the Altai region of Russia, Caucasians aged 20-93 years, who had COVID-19 from May 2020 to February 2021 (n = 314), took part in a onetime observational study. The level of antibodies in the blood was measured by enzyme-linked immunosorbent assay 1-14 months after the onset of the clinical manifestation of CO-VID-19. Results. Anti-RBD IgG antibodies of the SARS-CoV-2 spike protein were detected in 86.9% of the study participants. The dependence of the antibody titer on the duration of the period after COVID-19 was not revealed. The antibody titer was positively correlated with the complication of CO-VID-19 pneumonia and the volume of lung tissue lesions. The presence of pneumonia COVID-19 and the volume of lung tissue lesions are positively associated with age. Age positively correlated with antibody titer regardless of the pneumonia COVID-19 in the anamnesis. Conclusion. IgG antibodies to RBD of the SARS-CoV-2 spike protein are present in most of the COVID-19 patients. The titer of these antibodies in adults depends on age, complications of pneumonia COVID-19, and probably persists up to 14 months after the first symptoms of infection appear.Copyright © 2022 Interregional public organization Association of infectious disease specialists of Saint-Petersburg and Leningrad region (IPO AIDSSPbR). All rights reserved.

Molecular Docking Studies of Ocimum Americanum Secondary Metabolites Against SARS-Cov-2 Spike Protein

Introduction and Aim: The outbreak of Covid-19 pandemic since December 2019 has raised serious global health concern. Because of rapid human to human transmission and non-availability of clinically proven drugs or vaccines, this Covid-19 pandemic has created a great threat to mankind. Many naturally derived molecules are being investigated for the treatment of Covid-19. Ocimum americanum is one such significant medicinal plant possessing a variety of biological activities. Material(s) and Method(s): In the present study, seven phytochemicals were selected from O. americanum and were docked against SARS-CoV-2 spike protein which is an important site for virus to enter the host cell. Docking was performed using Autodock Vina and the ADME properties of all these seven ligands were predicted using the Swiss-ADME tool. The bioactivity score was also predicted using the Molinspiration tool. Besides the secondary metabolites, all these analyses were also performed for well-known antiviral drugs namely lopinavir and ritonavir. Result(s): The binding energy obtained from the docking studies of SARS-CoV-2 spike protein with Lopinavir, Ritonavir, Alpha-farnesene, Beta-farnesene, Eugenol, Linalool, Estragole, Limonene and 1,8-Cineole was found to be-5.2,-5.1,-4.7,-4.5,-4.3,-4.1,-4,-3.9 and-3.8 Kcal/Mol respectively. Swiss-ADME results also suggest that all the selected ligands follow the drug likeness properties and hence they could be taken for further drug discovery process. Conclusion(s): From the present in silico study, it can be concluded that secondary metabolites of O. americanum have potential inhibiting activity against spike protein of SARS-CoV-2. Isolation and efficacy studies in vitro may provide an insight into the drug discovery to fight Covid-19.Copyright © 2023, Indian Association of Biomedical Scientists. All rights reserved.

Development of an enzyme-linked immunosorbent assay based on viral antigen capture by anti-spike glycoprotein monoclonal antibody for detecting immunoglobulin A antibodies against porcine epidemic diarrhea virus in milk.

BACKGROUND: Porcine epidemic diarrhea (PED), caused by PED virus (PEDV), is a severe enteric disease burdening the global swine industry in recent years. Especially, the mortality of PED in neonatal piglets approaches 100%. Maternal antibodies in milk, particularly immunoglobulin A (IgA) antibodies, are of great importance for protection neonatal suckling piglets against PEDV infection as passive lactogenic immunity. Therefore, appropriate detection methods are required for detecting PEDV IgA antibodies in milk. In the current study, we prepared monoclonal antibodies (mAbs) against PEDV spike (S) glycoprotein. An enzyme-linked immunosorbent assay (ELISA) was subsequently developed based on PEDV antigen capture by a specific anti-S mAb. RESULTS: The developed ELISA showed high sensitivity (the maximum dilution of milk samples up to 1:1280) and repeatability (coefficient of variation values < 10%) in detecting PEDV IgA antibody positive and negative milk samples. More importantly, the developed ELISA showed a high coincidence rate with a commercial ELISA kit for PEDV IgA antibody detection in clinical milk samples. CONCLUSIONS: The developed ELISA in the current study is applicable for PEDV IgA antibody detection in milk samples, which is beneficial for evaluating vaccination efficacies and neonate immune status against the virus.