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1.
Innovation (Camb) ; 3(2): 100221, 2022 Mar 29.
Article in English | MEDLINE | ID: covidwho-1713028

ABSTRACT

The highly pathogenic and readily transmissible SARS-CoV-2 has caused a global coronavirus pandemic, urgently requiring effective countermeasures against its rapid expansion. All available vaccine platforms are being used to generate safe and effective COVID-19 vaccines. Here, we generated a live-attenuated candidate vaccine strain by serial passaging of a SARS-CoV-2 clinical isolate in Vero cells. Deep sequencing revealed the dynamic adaptation of SARS-CoV-2 in Vero cells, resulting in a stable clone with a deletion of seven amino acids (N679SPRRAR685) at the S1/S2 junction of the S protein (named VAS5). VAS5 showed significant attenuation of replication in multiple human cell lines, human airway epithelium organoids, and hACE2 mice. Viral fitness competition assays demonstrated that VAS5 showed specific tropism to Vero cells but decreased fitness in human cells compared with the parental virus. More importantly, a single intranasal injection of VAS5 elicited a high level of neutralizing antibodies and prevented SARS-CoV-2 infection in mice as well as close-contact transmission in golden Syrian hamsters. Structural and biochemical analysis revealed a stable and locked prefusion conformation of the S trimer of VAS5, which most resembles SARS-CoV-2-3Q-2P, an advanced vaccine immunogen (NVAX-CoV2373). Further systematic antigenic profiling and immunogenicity validation confirmed that the VAS5 S trimer presents an enhanced antigenic mimic of the wild-type S trimer. Our results not only provide a potent live-attenuated vaccine candidate against COVID-19 but also clarify the molecular and structural basis for the highly attenuated and super immunogenic phenotype of VAS5.

2.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-313382

ABSTRACT

Cytokine release syndrome (CRS) is a severe complication of infectious diseases such as coronavirus disease 2019 (COVID-19) that cause serious damage to public health. Currently, no effective therapeutic strategy exists for CRS treatment in clinic, and supportive therapy is still the main method. Here, we show the potential of macrophage membrane-biomimetic nanoparticles for CRS treatment. By fusing macrophage membrane on the surface of the PLGA skeleton, we constructed biomimetic nanoparticles that inherited the membrane receptors from the "parental" macrophages, enabling the neutralization of CRS-related cytokines. We compared three types of macrophage membranes to screen out more effective biomimetic nanoparticles for CRS treatment. Our results show that biomimetic nanoparticles containing M0 macrophage membrane can decrease the levels of pro-inflammatory cytokines involved in CRS to the greatest extent. In a mouse model of RNA virus analog-induced CRS, the macrophage membrane-biomimetic nanoparticles manifested significant therapeutic efficacy by reducing cytokine levels and alleviating organ damage.Funding Information: This work was supported by Scientific Research Project of Tongji University (22120200021), the National Natural Science Foundation of China (82073385 and 81803078), Shanghai Science and Technology Committee (20DZ2255200 and 21140901900).Declaration of Interests: The authors declare no conflict of interest.Ethics Approval Statement: All animal studies were approved under the guidelines of Tongji University Institutional Animal Care and Use Committee.

3.
Microbiol Spectr ; 10(1): e0155021, 2022 02 23.
Article in English | MEDLINE | ID: covidwho-1685499

ABSTRACT

Mycoplasma pneumoniae is a common pathogen causing respiratory disease in children. We sought to investigate the epidemiology of M. pneumoniae among outpatient children with mild respiratory tract infections (RTIs) during the coronavirus disease 2019 (COVID-19) pandemic. Eligible patients were prospectively enrolled from January 2020 to June 2021. Throat swabs were tested for M. pneumoniae RNA. M. pneumoniae IgM was tested by a colloidal gold assay. Macrolide resistance and the effect of the COVID-19 countermeasures on M. pneumoniae prevalence were assessed. Symptom scores, treatments, and outcomes were evaluated. Eight hundred sixty-two eligible children at 15 centers in China were enrolled. M. pneumoniae was detected in 78 (9.0%) patients. Seasonally, M. pneumoniae peaked in the first spring and dropped dramatically to extremely low levels over time until the next summer. Decreases in COVID-19 prevalence were significantly associated with decreases in M. pneumoniae prevalence (r = 0.76, P = 0.001). The macrolide resistance rate was 7.7%. The overall sensitivity and specificity of the colloidal gold assay used in determining M. pneumoniae infection were 32.1% and 77.9%, respectively. No more benefits for improving the severity of symptoms and outcomes were observed in M. pneumoniae-infected patients treated with a macrolide than in those not treated with a macrolide during follow-up. The prevalences of M. pneumoniae and macrolide resistance in outpatient children with mild RTIs were at low levels in the early stage of the COVID-19 pandemic but may have rebounded recently. The colloidal gold assay for M. pneumoniae IgM may be not appropriate for diagnosis of M. pneumoniae infection. Macrolides should be used with caution among outpatients with mild RTIs. IMPORTANCE This is the first and largest prospective, multicenter, active, population-based surveillance study of the epidemiology of Mycoplasma pneumoniae among outpatient children with mild respiratory tract infections (RTIs) during the COVID-19 pandemic. Nationwide measures like strict face mask wearing and restrictions on population movement implemented to prevent the spread of COVID-19 might also effectively prevent the spread of M. pneumoniae. The prevalence of M. pneumoniae and the proportion of drug-resistant M. pneumoniae isolates in outpatient children with mild RTIs were at low levels in the early stage of the COVID-19 pandemic but may have rebounded recently. The colloidal gold assay for M. pneumoniae IgM may be not appropriate for screening and diagnosis of M. pneumoniae infection. Macrolides should be used with caution among outpatients with mild RTIs.


Subject(s)
Mycoplasma pneumoniae/isolation & purification , Pneumonia, Mycoplasma/microbiology , Respiratory Tract Infections/microbiology , Adolescent , Adult , Anti-Bacterial Agents/therapeutic use , COVID-19/epidemiology , Child , Child, Preschool , China/epidemiology , Drug Resistance, Bacterial , Female , Humans , Infant , Macrolides/therapeutic use , Male , Mycoplasma pneumoniae/genetics , Mycoplasma pneumoniae/physiology , Outpatients/statistics & numerical data , Pneumonia, Mycoplasma/drug therapy , Pneumonia, Mycoplasma/epidemiology , Prospective Studies , Respiratory Tract Infections/drug therapy , Respiratory Tract Infections/epidemiology , Young Adult
4.
Nature ; 603(7903): 919-925, 2022 03.
Article in English | MEDLINE | ID: covidwho-1655591

ABSTRACT

Omicron (B.1.1.529), the most heavily mutated SARS-CoV-2 variant so far, is highly resistant to neutralizing antibodies, raising concerns about the effectiveness of antibody therapies and vaccines1,2. Here we examined whether sera from individuals who received two or three doses of inactivated SARS-CoV-2 vaccine could neutralize authentic Omicron. The seroconversion rates of neutralizing antibodies were 3.3% (2 out of 60) and 95% (57 out of 60) for individuals who had received 2 and 3 doses of vaccine, respectively. For recipients of three vaccine doses, the geometric mean neutralization antibody titre for Omicron was 16.5-fold lower than for the ancestral virus (254). We isolated 323 human monoclonal antibodies derived from memory B cells in triple vaccinees, half of which recognized the receptor-binding domain, and showed that a subset (24 out of 163) potently neutralized all SARS-CoV-2 variants of concern, including Omicron. Therapeutic treatments with representative broadly neutralizing monoclonal antibodies were highly protective against infection of mice with SARS-CoV-2 Beta (B.1.351) and Omicron. Atomic structures of the Omicron spike protein in complex with three classes of antibodies that were active against all five variants of concern defined the binding and neutralizing determinants and revealed a key antibody escape site, G446S, that confers greater resistance to a class of antibodies that bind on the right shoulder of the receptor-binding domain by altering local conformation at the binding interface. Our results rationalize the use of three-dose immunization regimens and suggest that the fundamental epitopes revealed by these broadly ultrapotent antibodies are rational targets for a universal sarbecovirus vaccine.


Subject(s)
COVID-19 Vaccines , COVID-19 , SARS-CoV-2 , Animals , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/isolation & purification , Antibodies, Monoclonal/therapeutic use , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/isolation & purification , Antibodies, Neutralizing/therapeutic use , Antibodies, Viral/immunology , Antibodies, Viral/isolation & purification , Antibodies, Viral/therapeutic use , COVID-19/immunology , COVID-19/prevention & control , COVID-19/virology , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/immunology , Disease Models, Animal , Humans , Mice , Neutralization Tests , SARS-CoV-2/classification , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology
5.
Cell ; 185(5): 860-871.e13, 2022 03 03.
Article in English | MEDLINE | ID: covidwho-1650841

ABSTRACT

The SARS-CoV-2 Omicron variant with increased fitness is spreading rapidly worldwide. Analysis of cryo-EM structures of the spike (S) from Omicron reveals amino acid substitutions forging interactions that stably maintain an active conformation for receptor recognition. The relatively more compact domain organization confers improved stability and enhances attachment but compromises the efficiency of the viral fusion step. Alterations in local conformation, charge, and hydrophobic microenvironments underpin the modulation of the epitopes such that they are not recognized by most NTD- and RBD-antibodies, facilitating viral immune escape. Structure of the Omicron S bound with human ACE2, together with the analysis of sequence conservation in ACE2 binding region of 25 sarbecovirus members, as well as heatmaps of the immunogenic sites and their corresponding mutational frequencies, sheds light on conserved and structurally restrained regions that can be used for the development of broad-spectrum vaccines and therapeutics.


Subject(s)
Immune Evasion/physiology , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/chemistry , Angiotensin-Converting Enzyme 2/chemistry , Angiotensin-Converting Enzyme 2/metabolism , Antibodies, Viral/immunology , Binding Sites , COVID-19/immunology , COVID-19/pathology , COVID-19/virology , Cryoelectron Microscopy , Humans , Mutagenesis, Site-Directed , Neutralization Tests , Protein Binding , Protein Domains/immunology , Protein Structure, Quaternary , SARS-CoV-2/isolation & purification , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Surface Plasmon Resonance , Virus Attachment
7.
Natl Sci Rev ; 8(8): nwab053, 2021 Aug.
Article in English | MEDLINE | ID: covidwho-1358471

ABSTRACT

Mutations and transient conformational movements of the receptor binding domain (RBD) that make neutralizing epitopes momentarily unavailable present immune escape routes for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To mitigate viral escape, we developed a cocktail of neutralizing antibodies (NAbs) targeting epitopes located on different domains of spike (S) protein. Screening of a library of monoclonal antibodies generated from peripheral blood mononuclear cells of COVID-19 convalescent patients yielded potent NAbs, targeting the N-terminal domain (NTD) and RBD domain of S, effective at nM concentrations. Remarkably, a combination of RBD-targeting NAbs and NTD-binding NAbs, FC05, enhanced the neutralization potency in cell-based assays and an animal model. Results of competitive surface plasmon resonance assays and cryo-electron microscopy (cryo-EM) structures of antigen-binding fragments bound to S unveil determinants of immunogenicity. Combinations of immunogens, identified in the NTD and RBD of S, when immunized in rabbits and macaques, elicited potent protective immune responses against SARS-CoV-2. More importantly, two immunizations of this combination of NTD and RBD immunogens provided complete protection in macaques against a SARS-CoV-2 challenge, without observable antibody-dependent enhancement of infection. These results provide a proof of concept for neutralization-based immunogen design targeting SARS-CoV-2 NTD and RBD.

8.
Front Public Health ; 9: 689870, 2021.
Article in English | MEDLINE | ID: covidwho-1282426

ABSTRACT

China is an emerging country, and government intervention is always considered as an important part of the solutions when people facing challenges in China. Under the impact of the coronavirus disease 2019 (COVID-19) epidemic and the global economic downturn, the Chinese government quickly brought the epidemic under control and restored the positive economic growth through strong intervention. Based on the panel data of provincial level in China and the government intervention as the threshold variable, this paper empirically analyzed the non-linear effect of business cycle on population health by using the panel threshold regression model. The empirical results show that the impact of the business cycle on population health is significantly negative, and government intervention has a single threshold effect on the relationship between business cycle and population health. When the government intervention is below the threshold value, the business cycle has a significant negative effect on the improvement of the population health level; when the level of government intervention exceeds the threshold value, the relationship between business cycle and population health becomes significantly positive. To some extent, the conclusions of this paper can guide the formulation and revision of government health policy and help to adjust the direction and intensity of government intervention. The Chinese government and other governments of emerging countries should do more to harness the power of state intervention in their response to the business cycle.


Subject(s)
Commerce , Government , Population Health , COVID-19 , China/epidemiology , Humans
9.
Natl Sci Rev ; 8(3): nwaa297, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-990776

ABSTRACT

Receptor recognition and subsequent membrane fusion are essential for the establishment of successful infection by SARS-CoV-2. Halting these steps can cure COVID-19. Here we have identified and characterized a potent human monoclonal antibody, HB27, that blocks SARS-CoV-2 attachment to its cellular receptor at sub-nM concentrations. Remarkably, HB27 can also prevent SARS-CoV-2 membrane fusion. Consequently, a single dose of HB27 conferred effective protection against SARS-CoV-2 in two established mouse models. Rhesus macaques showed no obvious adverse events when administrated with 10 times the effective dose of HB27. Cryo-EM studies on complex of SARS-CoV-2 trimeric S with HB27 Fab reveal that three Fab fragments work synergistically to occlude SARS-CoV-2 from binding to the ACE2 receptor. Binding of the antibody also restrains any further conformational changes of the receptor binding domain, possibly interfering with progression from the prefusion to the postfusion stage. These results suggest that HB27 is a promising candidate for immuno-therapies against COVID-19.

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