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1.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-336803

ABSTRACT

Neutralizing antibodies (NAbs) can prevent and treat infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, continuously emerging variants, such as Omicron, have significantly reduced the potency of most known NAbs. The selection of NAbs with broad neutralizing activities and the identification of conserved critical epitopes are still urgently needed. Here, we identified an extremely potent antibody (55A8) by single B-cell sorting from convalescent SARS-CoV-2-infected patients that recognized the receptor-binding domain (RBD) in the SARS-CoV-2 spike (S) protein. 55A8 could bind to wild-type SARS-CoV-2, Omicron BA.1 and Omicron BA.2 simultaneously with 58G6, a NAb previously identified by our group. Importantly, an antibody cocktail containing 55A8 and 58G6 (2-cocktail) showed synergetic neutralizing activity with a half-maximal inhibitory concentration (IC 50 ) in the picomolar range in vitro and prophylactic efficacy in hamsters challenged with Omicron (BA.1) through intranasal delivery at an extraordinarily low dosage (25 μg of each antibody daily) at 3 days post-infection. Structural analysis by cryo-electron microscopy (cryo-EM) revealed that 55A8 is a Class III NAb that recognizes a highly conserved epitope. It could block angiotensin-converting enzyme 2 (ACE2) binding to the RBD in the S protein trimer via steric hindrance. The epitopes in the RBD recognized by 55A8 and 58G6 were found to be different and complementary, which could explain the synergetic mechanism of these two NAbs. Our findings not only provide a potential antibody cocktail for clinical use against infection with current SARS-CoV-2 strains and future variants but also identify critical epitope information for the development of better antiviral agents.

2.
Biosens Bioelectron ; 209: 114226, 2022 Aug 01.
Article in English | MEDLINE | ID: covidwho-1767929

ABSTRACT

Protein sensors based on allosteric enzymes responding to target binding with rapid changes in enzymatic activity are potential tools for homogeneous assays. However, a high signal-to-noise ratio (S/N) is difficult to achieve in their construction. A high S/N is critical to discriminate signals from the background, a phenomenon that might largely vary among serum samples from different individuals. Herein, based on the modularized luciferase NanoLuc, we designed a novel biosensor called NanoSwitch. This sensor allows direct detection of antibodies in 1 µl serum in 45 min without washing steps. In the detection of Flag and HA antibodies, NanoSwitches respond to antibodies with S/N ratios of 33-fold and 42-fold, respectively. Further, we constructed a NanoSwitch for detecting SARS-CoV-2-specific antibodies, which showed over 200-fold S/N in serum samples. High S/N was achieved by a new working model, combining the turn-off of the sensor with human serum albumin and turn-on with a specific antibody. Also, we constructed NanoSwitches for detecting antibodies against the core protein of hepatitis C virus (HCV) and gp41 of the human immunodeficiency virus (HIV). Interestingly, these sensors demonstrated a high S/N and good performance in the assays of clinical samples; this was partly attributed to the combination of off-and-on models. In summary, we provide a novel type of protein sensor and a working model that potentially guides new sensor design with better performance.


Subject(s)
Biosensing Techniques , COVID-19 , Antibodies, Viral , COVID-19/diagnosis , Humans , Luciferases , SARS-CoV-2
3.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-329675

ABSTRACT

With the development of COVID-19, even though increased global vaccination coverage, a super variant of SARS-CoV-2, Omicron, carrying a great number of mutations, has been verified its strong capacity of immune escape. An increased risk of SARS-CoV-2 reinfection or breakthrough infection should be concerned. We analyzed the humoral immune response of Omicron breakthrough infection and found its cross-neutralization against VOCs. We established mouse models to verify whether Omicron-specific RBD subunit boost immune response by immunizing Omicron-RBD recombinant proteins. The results suggest that an additional boost vaccination with Omicron-RBD protein could increase humoral immune response against both WT and current VOCs.

4.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-313429

ABSTRACT

Accumulating mutations on SARS-CoV-2 Spike (S) protein may increase the possibility of immune escape, challenging the present COVID-19 prophylaxis and clinical interventions. Here, in a panel of receptor binding domain (S-RBD) specific monoclonal antibodies (mAbs) with high neutralizing potency against authentic SARS-CoV-2, at least 6 of them were found to efficiently block the pseudovirus of 501Y.V2, a highly transmissible SARS-CoV-2 variant with escape mutations. The top 3 neutralizing Abs (13G9, 58G6 and 510A5) exhibited comparative ultrapotency as those being actively pursued for clinical development. Interestingly, the antigenic sites for the majority of our neutralizing Abs overlapped with a single epitope (13G9e) on S-RBD. Further, the 3-dimensional structures of 2 ultrapotent neutralizing Abs 13G9 or 58G6 in complex with SARS-CoV-2 S trimer demonstrated that both Abs bound to a steric region within S 472–490 . Moreover, a specific linear region (S 450–457 ) was identified as an additional target for 58G6. Importantly, our cryo-electron microscopy (cryo-EM) analysis revealed a unique phenomenon that the S-RBDs interacting with the fragments of antigen binding (Fabs) of 13G9 or 58G6 encoded by the IGHV1-58 and the IGKV3-20 gene segments were universally in the ‘up’ conformation in all observed particles. The potent neutralizing Abs presented in the current study may be promising candidates to fulfill the urgent needs for the current pandemic of SARS-CoV-2, and may of fundamental value for the next-generation vaccine development.

5.
EuropePMC; 2020.
Preprint in English | EuropePMC | ID: ppcovidwho-311951

ABSTRACT

After the epidemic of COVID-19, neutralizing antibodies (NAbs) against SARS-CoV-2 has been developed for the preventative and therapeutic purposes. However, few methodologies are reported in detail on how to rapidly and efficiently generate NAbs of interest. Here, we present a strategically optimized screening method for NAbs, which has enabled us to obtain SARS-CoV-2 receptor-binding domain (RBD) specific monoclonal Abs within 4 days, followed by additional 2 days to evaluate their neutralizing activities. Using this method, we obtained 198 specific Abs against SARS-CoV-2 RBD from the blood samples of COVID-19 convalescent patients, and 96 of them showed neutralizing activity. At least 20% of these NAbs exhibited high neutralizing potency. The top 2 NAbs showed the half-maximal inhibitory concentration (IC50) to block authentic SARS-CoV-2 at 9.88 and 11.13 ng/ml, respectively. Altogether, our study provides a fundamental methodology for discovering NAbs with potential preventative and therapeutic value for emerging infectious diseases.

6.
EuropePMC; 2020.
Preprint in English | EuropePMC | ID: ppcovidwho-324239

ABSTRACT

The systemic cytokine release syndrome (CRS) is a major cause of the multi-organ injury and fatal outcome induced by SARS-CoV-2 infection in severe COVID-19 patients. It has been well-known that metabolism plays a role in modulating the immune responses in infectious diseases. Yet, how the host metabolism correlates with CRS in COVID-19 patients and how the perturbed metabolites affect the cytokine release remains unclear. Here, we performed both metabolomics and cytokine/chemokine profiling on serum samples from the same cohort of healthy controls, mild and severe COVID-19 patients and delineated the global metabolic and immune response landscape along disease progression. Intriguingly, the correlation analysis revealed the tight link between metabolites and proinflammatory cytokines and chemokines, such as IL-6, M-CSF, IL-1α, IL-1β, implying the potential regulatory role of arginine metabolism, tryptophan metabolism, and purine metabolism in hyperinflammation. Importantly, we demonstrated that targeting metabolism markedly modulated the proinflammatory cytokines release by PBMCs isolated from SARS-CoV-2-infected rhesus macaques ex vivo. Beyond providing a comprehensive resource of metabolism and immunology data of SARS-CoV-2 infection, our study showed that metabolic alterations can be potentially exploited to develop novel strategy for the treatment of fatal CRS in COVID-19.

7.
Nat Med ; 26(6): 845-848, 2020 06.
Article in English | MEDLINE | ID: covidwho-1641979

ABSTRACT

We report acute antibody responses to SARS-CoV-2 in 285 patients with COVID-19. Within 19 days after symptom onset, 100% of patients tested positive for antiviral immunoglobulin-G (IgG). Seroconversion for IgG and IgM occurred simultaneously or sequentially. Both IgG and IgM titers plateaued within 6 days after seroconversion. Serological testing may be helpful for the diagnosis of suspected patients with negative RT-PCR results and for the identification of asymptomatic infections.


Subject(s)
Antibodies, Viral/blood , Antibody Formation/drug effects , Betacoronavirus/pathogenicity , Coronavirus Infections/drug therapy , Pneumonia, Viral/drug therapy , Adult , Aged , Antibody Formation/immunology , Antiviral Agents/therapeutic use , Betacoronavirus/genetics , COVID-19 , Coronavirus Infections/blood , Coronavirus Infections/immunology , Coronavirus Infections/virology , Female , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Male , Middle Aged , Pandemics/prevention & control , Pneumonia, Viral/blood , Pneumonia, Viral/immunology , Pneumonia, Viral/virology , SARS-CoV-2
9.
Genes Dis ; 2021 Dec 03.
Article in English | MEDLINE | ID: covidwho-1616497

ABSTRACT

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The Spike protein that mediates coronavirus entry into host cells is a major target for COVID-19 vaccines and antibody therapeutics. However, multiple variants of SARS-CoV-2 have emerged, which may potentially compromise vaccine effectiveness. Using a pseudovirus-based assay, we evaluated SARS-CoV-2 cell entry mediated by the viral Spike B.1.617 and B.1.1.7 variants. We also compared the neutralization ability of monoclonal antibodies from convalescent sera and neutralizing antibodies (NAbs) elicited by CoronaVac (inactivated vaccine) and ZF2001 (RBD-subunit vaccine) against B.1.617 and B.1.1.7 variants. Our results showed that, compared to D614G and B.1.1.7 variants, B.1.617 shows enhanced viral entry and membrane fusion, as well as more resistant to antibody neutralization. These findings have important implications for understanding viral infectivity and for immunization policy against SARS-CoV-2 variants.

10.
Emerg Microbes Infect ; 11(1): 483-497, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-1606402

ABSTRACT

Coronavirus disease 2019 (COVID-19) caused by the emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has set off a global pandemic. There is an urgent unmet need for safe, affordable, and effective therapeutics against COVID-19. In this regard, drug repurposing is considered as a promising approach. We assessed the compounds that affect the endosomal acidic environment by applying human angiotensin-converting enzyme 2 (hACE2)- expressing cells infected with a SARS-CoV-2 spike (S) protein-pseudotyped HIV reporter virus and identified that obatoclax resulted in the strongest inhibition of S protein-mediated virus entry. The potent antiviral activity of obatoclax at nanomolar concentrations was confirmed in different human lung and intestinal cells infected with the SARS-CoV-2 pseudotype system as well as clinical virus isolates. Furthermore, we uncovered that obatoclax executes a double-strike against SARS-CoV-2. It prevented SARS-CoV-2 entry by blocking endocytosis of virions through diminished endosomal acidification and the corresponding inhibition of the enzymatic activity of the endosomal cysteine protease cathepsin L. Additionally, obatoclax impaired the SARS-CoV-2 S-mediated membrane fusion by targeting the MCL-1 protein and reducing furin protease activity. In accordance with these overarching mechanisms, obatoclax blocked the virus entry mediated by different S proteins derived from several SARS-CoV-2 variants of concern such as, Alpha (B.1.1.7), Beta (B.1.351), and Delta (B.1.617.2). Taken together, our results identified obatoclax as a novel effective antiviral compound that keeps SARS-CoV-2 at bay by blocking both endocytosis and membrane fusion. Our data suggested that obatoclax should be further explored as a clinical drug for the treatment of COVID-19.


Subject(s)
Cathepsins/metabolism , Furin/metabolism , Indoles/pharmacology , Pyrroles/pharmacology , SARS-CoV-2 , Virus Internalization/drug effects , COVID-19 , Humans , Hydrogen-Ion Concentration , SARS-CoV-2/drug effects , Spike Glycoprotein, Coronavirus
11.
Nat Commun ; 12(1): 6304, 2021 11 02.
Article in English | MEDLINE | ID: covidwho-1500462

ABSTRACT

Accumulating mutations in the SARS-CoV-2 Spike (S) protein can increase the possibility of immune escape, challenging the present COVID-19 prophylaxis and clinical interventions. Here, 3 receptor binding domain (RBD) specific monoclonal antibodies (mAbs), 58G6, 510A5 and 13G9, with high neutralizing potency blocking authentic SARS-CoV-2 virus display remarkable efficacy against authentic B.1.351 virus. Surprisingly, structural analysis has revealed that 58G6 and 13G9 both recognize the steric region S470-495 on the RBD, overlapping the E484K mutation presented in B.1.351. Also, 58G6 directly binds to another region S450-458 in the RBD. Significantly, 58G6 and 510A5 both demonstrate prophylactic efficacy against authentic SARS-CoV-2 and B.1.351 viruses in the transgenic mice expressing human ACE2 (hACE2), protecting weight loss and reducing virus loads. Together, we have evidenced 2 potent neutralizing Abs with unique mechanism targeting authentic SARS-CoV-2 mutants, which can be promising candidates to fulfill the urgent needs for the prolonged COVID-19 pandemic.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Animals , Antibodies, Monoclonal/administration & dosage , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/administration & dosage , Antibodies, Neutralizing/chemistry , Antibodies, Viral/administration & dosage , Antibodies, Viral/chemistry , Binding Sites , COVID-19/pathology , COVID-19/virology , Epitopes , Humans , Mice , Mice, Transgenic , Mutation , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Viral Load/drug effects , Weight Loss/drug effects
14.
Clin Infect Dis ; 73(3): e531-e539, 2021 08 02.
Article in English | MEDLINE | ID: covidwho-1338662

ABSTRACT

BACKGROUND: Coronavirus disease 2019 (COVID-19) is a global pandemic with no licensed vaccine or specific antiviral agents for therapy. Little is known about the longitudinal dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific neutralizing antibodies (NAbs) in patients with COVID-19. METHODS: Blood samples (n = 173) were collected from 30 patients with COVID-19 over a 3-month period after symptom onset and analyzed for SARS-CoV-2-specific NAbs using the lentiviral pseudotype assay, coincident with the levels of IgG and proinflammatory cytokines. RESULTS: SARS-CoV-2-specific NAb titers were low for the first 7-10 days after symptom onset and increased after 2-3 weeks. The median peak time for NAbs was 33 days (interquartile range [IQR], 24-59 days) after symptom onset. NAb titers in 93.3% (28/30) of the patients declined gradually over the 3-month study period, with a median decrease of 34.8% (IQR, 19.6-42.4%). NAb titers increased over time in parallel with the rise in immunoglobulin G (IgG) antibody levels, correlating well at week 3 (r = 0.41, P < .05). The NAb titers also demonstrated a significant positive correlation with levels of plasma proinflammatory cytokines, including stem cell factor (SCF), TNF-related apoptosis-inducing ligand (TRAIL), and macrophage colony-stimulating factor (M-CSF). CONCLUSIONS: These data provide useful information regarding dynamic changes in NAbs in patients with COVID-19 during the acute and convalescent phases.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing , Antibodies, Viral , Humans , Pandemics
15.
Front Immunol ; 12: 653189, 2021.
Article in English | MEDLINE | ID: covidwho-1172966

ABSTRACT

After the pandemic of COVID-19, neutralizing antibodies (NAbs) against SARS-CoV-2 have been developed for the prophylactic and therapeutic purposes. However, few methodologies are described in detail on how to rapidly and efficiently generate effective NAbs to SARS-CoV-2. Here, we integrated and optimized a strategically screening method for NAbs, which has enabled us to obtain SARS-CoV-2 receptor-binding domain (RBD) specific NAbs within 6 days, followed by additional 9 days for antibody production and function analysis. Using this method, we obtained 198 specific Abs against SARS-CoV-2 RBD from the blood samples of COVID-19 convalescent patients, and 96 of them showed neutralizing activity. At least 20% of these NAbs exhibited advanced neutralizing potency and high affinity, with the top two NAbs showing half-maximal inhibitory concentration (IC50) to block authentic SARS-CoV-2 at 9.88 and 11.13 ng/ml, respectively. Altogether, our study provides an effective methodology with high applicable value for discovering potential preventative and therapeutic NAbs for the emerging infectious diseases.


Subject(s)
Antibodies, Neutralizing , Antibodies, Viral , COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing/blood , Antibodies, Neutralizing/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , COVID-19/blood , COVID-19/immunology , Humans , SARS-CoV-2/immunology , SARS-CoV-2/metabolism
16.
Cell Discov ; 7(1): 18, 2021 Mar 25.
Article in English | MEDLINE | ID: covidwho-1152838

ABSTRACT

It is important to evaluate the durability of the protective immune response elicited by primary infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we systematically evaluated the SARS-CoV-2-specific memory B cell and T cell responses in healthy controls and individuals recovered from asymptomatic or symptomatic infection approximately 6 months prior. Comparatively low frequencies of memory B cells specific for the receptor-binding domain (RBD) of spike glycoprotein (S) persisted in the peripheral blood of individuals who recovered from infection (median 0.62%, interquartile range 0.48-0.69). The SARS-CoV-2 RBD-specific memory B cell response was detected in 2 of 13 individuals who recovered from asymptomatic infection and 10 of 20 individuals who recovered from symptomatic infection. T cell responses induced by S, membrane (M), and nucleocapsid (N) peptide libraries from SARS-CoV-2 were observed in individuals recovered from coronavirus disease 2019 (COVID-19), and cross-reactive T cell responses to SARS-CoV-2 were also detected in healthy controls.

17.
Nat Commun ; 12(1): 1618, 2021 03 12.
Article in English | MEDLINE | ID: covidwho-1132072

ABSTRACT

Cytokine release syndrome (CRS) is a major cause of the multi-organ injury and fatal outcome induced by SARS-CoV-2 infection in severe COVID-19 patients. Metabolism can modulate the immune responses against infectious diseases, yet our understanding remains limited on how host metabolism correlates with inflammatory responses and affects cytokine release in COVID-19 patients. Here we perform both metabolomics and cytokine/chemokine profiling on serum samples from healthy controls, mild and severe COVID-19 patients, and delineate their global metabolic and immune response landscape. Correlation analyses show tight associations between metabolites and proinflammatory cytokines/chemokines, such as IL-6, M-CSF, IL-1α, IL-1ß, and imply a potential regulatory crosstalk between arginine, tryptophan, purine metabolism and hyperinflammation. Importantly, we also demonstrate that targeting metabolism markedly modulates the proinflammatory cytokines release by peripheral blood mononuclear cells isolated from SARS-CoV-2-infected rhesus macaques ex vivo, hinting that exploiting metabolic alterations may be a potential strategy for treating fatal CRS in COVID-19.


Subject(s)
COVID-19/immunology , COVID-19/metabolism , Cytokine Release Syndrome/immunology , Cytokine Release Syndrome/metabolism , Cytokines/blood , Metabolome , SARS-CoV-2 , Animals , COVID-19/therapy , Case-Control Studies , Cohort Studies , Cytokine Release Syndrome/therapy , Female , Follow-Up Studies , Humans , In Vitro Techniques , Inflammation Mediators/blood , Leukocytes, Mononuclear/immunology , Leukocytes, Mononuclear/metabolism , Longitudinal Studies , Macaca mulatta , Male , Metabolic Networks and Pathways , Pandemics
20.
Genes Dis ; 7(4): 551-557, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-651764

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative virus of the coronavirus disease 2019 (COVID-19) pandemic. To establish a safe and convenient assay system for studying entry inhibitors and neutralizing antibodies against SARS-CoV-2, we constructed a codon-optimized, full-length C-terminal mutant spike (S) gene of SARS-CoV-2. We generated a luciferase (Luc)-expressing pseudovirus containing the wild-type or mutant S protein of SARS-CoV-2 in the envelope-defective HIV-1 backbone. The key parameters for this pseudovirus-based assay, including the S mutants and virus incubation time, were optimized. This pseudovirus contains a Luc reporter gene that enabled us to easily quantify virus entry into angiotensin-converting enzyme 2 (ACE2)-expressing 293T cells. Cathepsin (Cat)B/L inhibitor E-64d could significantly block SARS-CoV-2 pseudovirus infection in 293T-ACE2 cells. Furthermore, the SARS-CoV-2 spike pseudotyped virus could be neutralized by sera from convalescent COVID-19 patients or recombinant ACE2 with the fused Fc region of human IgG1. Thus, we developed a pseudovirus-based assay for SARS-CoV-2, which will be valuable for evaluating viral entry inhibitors and neutralizing antibodies against this highly pathogenic virus.

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