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Introduction. The rapid spread of a new coronavirus infection among populations in many countries worldwide has contributed to the genetic evolution of the virus, resulting in the emergence of multiple genetic variants of the SARSCoV-2 coronavirus. Mutations in the viral genome can affect the ability of the virus to bypass the immune system and complicate development of diagnostic and prophylactic drugs. Data on the neutralizing activity of the sera obtained against previously circulating genetic variants of the virus in relation to current SARS-CoV-2 strains may serve as a scientific basis for the selection of the antigens in vaccine development. The aim of this work was to study cross-reactivity of SARSCoV-2 coronavirus strains belonging to different genetic variants, which were isolated in the territory of the Russian Federation during 2020-2022 in the neutralization reaction using mouse hyperimmune sera. Materials and methods. Ten strains of SARS-CoV-2 coronavirus belonging to different genetic variants were used (three non-VOC strains, alpha, beta, gamma, delta, delta+AY, omicron 1 and omicron 2). The hCoV-19/Australia/VIC01/2020 strain (Wuhan) was included in the study as a prototypical variant. BALBc mice were immunized with inactivated concentrated antigen mixed with a 1:1 adjuvant, which was a virus-like immunostimulatory complex based on Quillaja saponaria (Quillaja saponaria). The antibody titer was determined in the neutralization reaction. Results. Essential decrease of neutralizing ability of antibodies specific to non-vOC genetic variants of SARS-CoV-2 coronavirus was revealed against beta VOC and to a lesser degree against alpha and gamma VOC variants. The differences in the neutralizing activity level of antibodies for alpha and beta VOC variants are not significant among themselves, and with gamma VOC variants - there are no significant differences. Neutralizing ability of antibodies specific to delta VOC against alpha and beta VOC variants decreased 4-fold. Neutralizing activity of sera obtained to omicron 1 and 2 variants in relation to the prototype coronavirus variant was reduced 18-fold, to the gamma variant - 12-fold, to delta variants - more than 30-fold;for other variants it was even lower. Conclusions. The results obtained testify to the presence of cross-reactivity between strains of coronavirus belonging to genetic lines Wuhan, alpha, beta, gamma;it is weaker for delta variants. Mutations in the genome of VOC omicron variants led to a significant decrease in antigenic cross-links with earlier genetic variants of the coronavirus. These findings explain the low efficacy of vaccines based on the Wuhan strain, synthetic immunogens, and recombinant proteins based on it against omicron VOC variants, which have caused a rise in morbidity since early 2022, as well as cases of re-infection of humans with new genetic variants of the coronavirus.Copyright © 2023 Saint Petersburg Pasteur Institute. All rights reserved.
ABSTRACT
Background: The rapid emergence of the SARS-CoV-2 Omicron variant that evades many therapies illustrates the need for antiviral treatments with high genetic barriers to resistance. The small molecule PAV-104, identified through a moderate-throughput screen involving cell-free protein synthesis, was recently shown to target a subset of host protein assembly machinery in a manner specific to viral assembly with minimal host toxicity. The chemotype shows broad activity against respiratory viral pathogens, including Orthomyxoviridae, Paramyxoviridae, Adenoviridae, Herpesviridae, and Picornaviridae, with low susceptibility to evolutionary escape. Here, we investigated the capacity of PAV-104 to inhibit SARS-CoV-2 replication in human airway epithelial cells (AECs). Method(s): Dose-dependent cytotoxicity of PAV-104 in Calu-3 cells was determined by MTT assay. Calu-3 cells were infected with SARS-CoV-2 isolate USA-WA1/2020 (MOI=0.01). Primary AECs were isolated from healthy donor lung transplant tissue, cultured at air liquid interface (ALI), and infected with SARS-CoV-2 Gamma, Delta, and Omicron variants (MOI=0.1). SARS-CoV-2 replication was assessed by RT-PCR quantitation of the N gene, immunofluorescence assay (IFA) of nucleocapsid (N) protein, and titration of supernatant (TCID50). Transient co-expression of four SARS-CoV-2 structural proteins (N, M, S, E) to produce virus-like particles (VLPs) was used to study the effect of PAV-104 on viral assembly. Drug resin affinity chromatography was performed to study the interaction between PAV-104 and N. Glycerol gradient sedimentation was used to assess N oligomerization. Total RNA-seq and the REACTOME database were used to evaluate PAV-104 effects on the host transcriptome. Result(s): PAV-104 reached 50% cytotoxicity in Calu-3 cells at 3732 nM (Fig.1A). 50 nM PAV-104 inhibited >99% of SARS-CoV-2 infection in Calu-3 cells (p< 0.01) and in primary AECs (p< 0.01) (Fig.1B-E). PAV-104 specifically inhibited SARS-CoV-2 post entry, and suppressed production of SARS-CoV-2 VLPs without affecting viral protein synthesis. PAV-104 interacted with SARS-CoV-2 N and interfered with N oligomerization. Transcriptome analysis revealed that PAV-104 treatment reversed SARS-CoV-2 induction of the interferon and maturation of nucleoprotein signaling pathways. Conclusion(s): PAV-104 is a pan-respiratory virus small molecule inhibitor with promising activity against SARS-CoV-2 in human airway epithelial cells that should be explored in animal models and clinical studies.
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 Omicron variant of SARS-CoV-2 is a new variant of concern after Alpha, Beta, Gamma and Delta variants. The amino acid mutations in the viral antigens, especially in the receptor binding region (RBD) of spike protein, were significantly more than those of other variants, which lead to the significant increase of infectivity, transmissibility and immune escape of Omicron variant. In addition, those spike mutations impaired the protective effect of vaccination. When compared to the infection of other variants, the latency of Omicron variant infection was significantly shortened, and the pathogenicity decreased markedly, which is in consistence with the fact that the vast majority of infected individuals showed no symptoms or only mild disease. Exacerbations in patients infected by Omicron variant were often associated with the progress of underlying disease. Early detection and medical isolation of infected persons, careful personal protection measures to cut off transmission routes, and active vaccination to protect susceptible people are key measures to prevent the spread of Omicron variant epidemic. A small number of patients infected with Omicron variant may develop so-called long COVID-19, post-COVID-19 syndrome, or post-COVID-19 condition, which means that long-term follow-up is needed in those patients. Effective anti-Omicron variant therapy can shorten the course of infection, promote the recovery from infection, and also contribute to the control of infection. Therefore, the development of antiviral drugs with ideal cost-benefit ratio and convenient administration is one of the research hotspot in the future.Copyright © 2022 Authors. All rights reserved.
ABSTRACT
Treatment of COVID-19 that is based on plants could be a more cost-effective therapy against the disease. Flavonoids, a group of compounds that have been observed to have various effects, including antiviral activity, were chosen as the candidate molecule for treatment of COVID-19. Kalanchoe Pinnata is one of the plants containing flavonoids that has been demonstrated to have antiviral activity. The structure of ACE2 and various flavonoids were retrieved and cleaned from unnecessary residues. The ACE2 structure was subjected to molecular docking in order to analyze the binding affinity. Following that, the ADME properties of each flavonoid were analyzed accordingly. The QSAR analysis was also performed for each type of flavonoid. Lastly, molecular dynamics simulation was conducted. All of the tested compounds were able to bind to human ACE2 and SARS-CoV-2 Spike protein, but were unable to compete with them as the binding affinity of the compounds to the protein were lower compared to ACE2-Spike interaction. The ADME and toxicity analysis showed that most of the ligands were able to be absorbed by the GI tract, but have low bioavailability. The compounds also cause no major toxicity effects and were able to be sufficiently distributed to the body. Molecular dynamics analysis also revealed that among the compounds, quercetin and rutin were able to interact with ACE2 and Spike protein stably. The QSAR analysis showed that friedelin, kaempferol, quercetin, and rutin are mostly non-toxic, but the high Cramer values indicate that there are no initial safety impressions for these molecules and could cause toxicity. In conclusion, quercetin and rutin have potential to be a candidate for COVID-19 drug development based on the in-silico predictions results obtained. Friedelin and Narcissin whose affinity to the proteins were relatively stronger but had unstable interactions from molecular dynamics simulation results, may also be a potential COVID-19 treatment with further investigation. However, further research is required to assess the effectiveness and also specially to measure the toxicity of the compounds. © 2022 Malaysian Journal of Fundamental and Applied Sciences.
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Critically ill patients infected with SARS-CoV-2 display adaptive immunity, but it is unknown if they develop cross-reactivity to variants of concern (VOCs). We profiled cross-immunity against SARS-CoV-2 VOCs in naturally infected, non-vaccinated, critically ill COVID-19 patients. Wave-1 patients (wild-type infection) were similar in demographics to Wave-3 patients (wild-type/alpha infection), but Wave-3 patients had higher illness severity. Wave-1 patients developed increasing neutralizing antibodies to all variants, as did patients during Wave-3. Wave-3 patients, when compared to Wave-1, developed more robust antibody responses, particularly for wild-type, alpha, beta and delta variants. Within Wave-3, neutralizing antibodies were significantly less to beta and gamma VOCs, as compared to wild-type, alpha and delta. Patients previously diagnosed with cancer or chronic obstructive pulmonary disease had significantly fewer neutralizing antibodies. Naturally infected ICU patients developed adaptive responses to all VOCs, with greater responses in those patients more likely to be infected with the alpha variant, versus wild-type.
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Introduction SARS-CoV-2 variants of concern (VOCs) represent an alarming threat as they may escape vaccination effectiveness. Broad-spectrum antivirals could complement and further enhance preventive benefits achieved through SARS-CoV-2 vaccination campaigns. Aim Testing the antiviral activity of Echinacea purpurea against VOCs and exploring underlying modes-of-action. Method A hydroethanolic extract of freshly harvested E. purpurea herb and roots (Echinaforce®, EF extract) was tested to inhibit infection of VOCs B1.1.7 (alpha), B.1.351.1 (beta), P.1 (gamma), B1.617.2 (delta), AV.1 (Scottish) and B1.525 (eta). Molecular dynamics (MD) were used to study interaction of EF phytochemical markers with known pharmacological viral and host cell targets. Results EF broadly inhibited propagation of all tested SARS-CoV-2 VOCs at EC50 < 12.0 ;jg/ml. Treatment of epithelial cells with 20 jg/ml EF prevented sequential infection with SARS-CoV-2 (Hu-1). MD analyses showed for alkylamides, caftaric acid and feruoyl-tartaric constant binding affinity to spike proteins of all VOCs and to TMPRSS-2, a serine protease required for virus endocytosis. Conclusion EF extract exhibits virucidal activity against all tested SARS-CoV-2 VOCs and protects epithelial cells from infection.
ABSTRACT
Introduction: The rapid emergence of the SARS-CoV-2 Omicron variant that evades many monoclonal antibody therapies illustrates the need for anti-viral treatments with low susceptibility to evolutionary escape. The small molecule PAV-104, identified through a moderate-throughput screen involving cell-free protein synthesis, was recently shown to target a subset of host protein assembly machinery in a manner specific to viral assembly. This compound has minimal host toxicity, including once daily oral dosing in rats that achieves >200-fold of the 90% effective concentration (EC90) in blood. The chemotype shows broad activity against respiratory viral pathogens, including Orthomyxoviridae, Paramyxoviridae, Adenoviridae, Herpesviridae, and Picornaviridae, with low suceptability to evolutionary escape. We hypothesized that PAV-104 would be active against SARSCoV- 2 variants in human airway epithelial cells. Methods: Airway epithelial cells were differentiated from lung transplant tissue at air-liquid interface (ALI) for four weeks prior to challenge with Alpha (Pango lineage designation B.1.1.7), Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2) SARS-CoV-2 variants. Viral replication was determined by quantitative PCR measurement of the SARS-CoV-2 nucleocapsid (N) gene. Dose-dependent virus inhibition and cytotoxicity of PAV-104 in the Calu-3 airway epithelial cell line was determined by PCR and MTT assay. Student's t-tests were used to evaluate statistical significance. Results: Alpha, Beta, Gamma, and Delta variants of SARS-CoV-2 showed comparable infectivity in human primary airway epithelial cells at ALI (N=3 donors), 47- to 550-fold higher than the parent (USA-WA1/2020) strain. PAV-104 reached 50% cytotoxicity in Calu-3 cells at 240 nM (Fig. 1A). Dose-response studies in Calu-3 cells demonstrated PAV-104 has a 6 nM 50% inhibitory concentration (IC50) for blocking replication of SARS-CoV-2 (USA-WA1/2020) (Fig.1B). In primary cells at ALI from 3 donors tested, there was >99% inhibition of infection by SARS-CoV-2 Gamma variant (N=3, MOI 0.1, P <0.01) with 100 nM PAV-104 (Fig. 1C). Addition of 100 nM PAV-104 2-hours post-infection, but not pre-infection, resulted in >99% suppression of viral replication, indicating a post-entry drug mechanism. PAV-104 bound a small subset of the known allosteric modulator 14-3-3, itself implicated in the interactome of SARS-CoV-2. Conclusion: PAV-104 is a host-targeted, orally bioavailable, pan-viral small molecule inhibitor with promising activity against SARS-CoV-2 variants in human primary airway epithelial cells. (Figure Presented).
ABSTRACT
Background: Few data are available about comparison of different monoclonal antibodies (MAbs) for COVID-19 in the real-world setting. We aim to compare effectiveness of bamlanivimab/etesevimab (BAM/ETE) versus (vs) casirivimab/imdevimab (CAS/IMD) and to estimate predictors of hospitalization/death. Methods: Observational analysis of all consecutive outpatients (pts) with mild/moderate COVID-19 enrolled within the AIFA access program in a single center in Rome, from March to October, 2021. At first baseline (BL) visit, RT-PCR from nasopharyngeal swab with cycle thereshold (CT) measurement and viral sequencing was performed. Pts received intravenous BAM/ETE (700/1400 mg) or CAS/IMD (1200/1200 mg) and were followed through day 30. Primary endpoint was hospitalization/death due to severe COVID-19 by day 30. Average treatment effect (ATE) in the multiplicative scale of the odds was the chosen estimand to compare the two treatments, adjusted for age, obesity, time from onset to infusion, median C-reactive protein (CRP), vaccination, variant of concern (VOC) and BL-CT. Predictors of clinical failure were explored by two different models of multivariable logistic regression. Results: 242 pts receiving BAM/ETE (n=76) or CAS/IMD (n=166) were included (male 54%;median age 65 yrs;median SpO2 97%;diabetes 12%;hypertension 40%;CVD 17%;COPD 26%;autoimmune diseases 12%;immunodeficiency 18%). Median time from symptoms onset to infusion was 4 days (IQR 3-6). No differences were observed between the two MAbs for BL characteristics except for BMI>35 (BAM/ETE 24%, CAS/IMD 12%), CRP (BAM/ETE 1.8, CAS/IMD 1.2), vaccination (BAM/ETE 26%, CAS/IMD 46%) and distribution of VOC (Alpha 46% BAM/ETE vs 22% CAS/IMD;Gamma 20% vs 7%;Delta 5% vs 55%). Proportion of patients with COVID-related hospitalization/death by day 30 was 12/76 (15.8%) for BAM/ETE and 6/166 (3.6%) for CAS/IMD. Estimate of causal effect of BAM/ETE exposure compared to CAS/IMD on primary end point by ATE is reported in Table 1a. Factors associated with an increased risk of clinical failure by fitting multivariable logistic regression were BMI >35 and P1/Gamma VOC;higher BL-CT was associated with a reduced risk (Table 1b-1c). Conclusion: In a real-life setting, receiving BAM/ETE was associated with a 4-fold higher risk of COVID-19 progression to hospitalization/death than CAS/IMD. SARS-CoV-2 P.1/Gamma, but not B.1617.2/Delta VOC, obesity and higher BL viral load also predicted an increased risk of clinical worsening.
ABSTRACT
Background: The continuing spread of SARS-CoV-2 provides opportunities for the virus to evolve. Compared to ancestral strains, the 4 major variants of concern (VOC) exhibit Spike mutations that improve entry and/or diminish antibody neutralization. However, mutations have arisen in other viral genes. Several of these genes may counteract innate immunity mediated by antiviral interferons (IFNs). IFNs show extensive diversity, but only IFNα2 and IFNβ are approved for clinical use. We showed previously that diverse IFNs exhibit variable activities against HIV-1 and trigger distinct transcriptomes. Methods: To assess whether SARS-CoV-2 acquired human IFN resistance over time, isolates representing early lineages A, B, B.1, and VOC lineages B.1.1.7 (alpha), B.1.351 (beta), P.1 (gamma) and B.1.617.2 (delta) were tested for sensitivity to multiple IFNs in an alveolar type II epithelial cell (AT2) line, A549, overexpressing ACE2. Cells were pre-treated with IFNs for 18 h in triplicate, then infected to yield ∼105 copies/reaction. Virus copy numbers were evaluated at 24 h by qPCR. We compared the sensitivity of 5 SARS-CoV-2 isolates to 12 IFNα subtypes, IFNβ, IFNω and 3 IFNa;subtypes at 2 pM, within the dynamic range of preliminary IFN inhibition curves. IC50s for IFNβ and IFNa;1 were compared between lineage B and VOC isolates. Results: Among the 17 IFNs tested, IFNβ, IFNα8, IFNω and IFNα5 most potently inhibited SARS-CoV-2 in A549-ACE2 cells. Inhibition curves with a delta variant isolate showed that IFNα2 and IFNa;1 had >10-fold and >1000-fold higher IC50 than IFNβ, respectively. Interestingly, the antiviral activity patterns of diverse IFNα subtypes against SARS-CoV-2 and HIV-1 were different and did not significantly correlate. Compared to the ancestral lineage B, the alpha, beta, gamma and delta variants exhibited on average 5.2-fold (range: 1.9-8.2) and 6.7-fold (range: 1.3-21) fold higher IC50s for IFNβ and IFNa;1, respectively. The alpha and delta isolates were also more resistant to IFNβ and IFNa;1 than a lineage B.1 isolate in another AT2 cell line, Calu-3. Conclusion: Our findings suggest that diverse IFNs may have evolved to restrict distinct virus families. Emerging SARS-CoV-2 variants are more effective than earlier pandemic viruses at antagonizing antiviral IFN responses. These data have implications for deploying IFNs for early COVID-19 therapy and suggest that innate immunity may be a driving force for SARS-CoV-2 evolution.
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Background: Galectin-9 (Gal-9) is a β-galactoside-binding lectin involved in immune regulation and viral immunopathogenesis. Multiple recent reports demonstrate that plasma levels of Gal-9 are elevated in the setting of severe COVID-19 disease. However, a causal role of Gal-9 in SARS-CoV-2 pathology remains to be elucidated. Here, we determined the impact of Gal-9 on SARS-CoV-2 replication and pro-inflammatory signaling in immortalized and primary human airway epithelial cells (AECs). Methods: Dose-dependent cytotoxicity of recombinant human Gal-9 in the Calu-3 AEC line was determined by MTT assay. Calu-3 cells were infected with SARS-CoV-2 isolate USA-WA1/2020 (MOI=0.01). Primary AECs were isolated from healthy donor lung transplant tissue, cultured at air liquid interface (ALI), and infected with SARS-CoV-2 lineage P.1 (MOI=0.1). SARS-CoV-2 replication was assessed by RT-PCR quantitation of the nucleocapsid (N) gene, immunofluorescence assay (IFA) of N protein, and titration of supernatant (TCID50). Viral entry was measured using luciferase activity of VSV-SARS-CoV-2 S-ΔG-Luciferase reporter pseudovirus. ACE2 and TMPRSS2 cell-surface expression were measured by flow cytometry. Pro-inflammatory factors (IL-6, IL-8, and TNFα) were detected by RT-PCR. Total RNA-seq was used to evaluate Gal-9 effects on the host transcriptome. Groups were compared by Student's t-test, and differential expression analyses were performed using DESeq2. Results: Gal-9 reached 50% cytotoxicity in Calu-3 cells at 597 nM. Gal-9 significantly increased SARS-CoV-2 expression (8.1 to 25.5 fold;p<0.0001) and infectious virus release (1.9 to 17.8 fold;p<0.038) in a dose-dependent manner in Calu-3 cells. Pseudovirus entry into Calu-3 cells was enhanced by Gal-9 (2.4 to 5.6 fold;p<0.0016), and the enhanced entry was inhibited by anti-ACE2 antibody (p<0.0027). Cell surface ACE2 and TMPRSS2 expression were unaffected by Gal-9. Gal-9 treatment accelerated virus-induced expression of IL-6, IL-8, and TNFα (p<0.018) in Calu-3 cells. Gal-9 increased SARS-CoV-2 production (p=0.03) and pro-inflammatory factor expression (p<0.05) in primary AECs (N=5 donors). RNA-seq data revealed that Gal-9 significantly induced IL-17, EIF2, IL-8 and IL-6 signaling pathways in the setting of SARS-CoV-2 infection. Conclusion: Gal-9 facilitates SARS-CoV-2 entry, replication, and virus-induced pro-inflammatory signaling in AECs ex vivo. Our data suggest that pharmacologic manipulation of Gal-9 should be explored as a SARS-CoV-2 therapeutic strategy.