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1.
Nat Commun ; 13(1): 3589, 2022 06 23.
Article in English | MEDLINE | ID: covidwho-1900488

ABSTRACT

The strikingly high transmissibility and antibody evasion of SARS-CoV-2 Omicron variants have posed great challenges to the efficacy of current vaccines and antibody immunotherapy. Here, we screen 34 BNT162b2-vaccinees and isolate a public broadly neutralizing antibody ZCB11 derived from the IGHV1-58 family. ZCB11 targets viral receptor-binding domain specifically and neutralizes all SARS-CoV-2 variants of concern, especially with great potency against authentic Omicron and Delta variants. Pseudovirus-based mapping of 57 naturally occurred spike mutations or deletions reveals that S371L results in 11-fold neutralization resistance, but it is rescued by compensating mutations in Omicron variants. Cryo-EM analysis demonstrates that ZCB11 heavy chain predominantly interacts with Omicron spike trimer with receptor-binding domain in up conformation blocking ACE2 binding. In addition, prophylactic or therapeutic ZCB11 administration protects lung infection against Omicron viral challenge in golden Syrian hamsters. These results suggest that vaccine-induced ZCB11 is a promising broadly neutralizing antibody for biomedical interventions against pandemic SARS-CoV-2.


Subject(s)
Antibodies, Viral , Broadly Neutralizing Antibodies , COVID-19 , Animals , Antibodies, Viral/immunology , BNT162 Vaccine , Broadly Neutralizing Antibodies/immunology , COVID-19/prevention & control , Cricetinae , Humans , Mesocricetus , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
2.
Sci Bull (Beijing) ; 67(13): 1372-1387, 2022 Jul 15.
Article in English | MEDLINE | ID: covidwho-1867754

ABSTRACT

Remarkable progress has been made in developing intramuscular vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, they are limited with respect to eliciting local immunity in the respiratory tract, which is the primary infection site for SARS-CoV-2. To overcome the limitations of intramuscular vaccines, we constructed a nasal vaccine candidate based on an influenza vector by inserting a gene encoding the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2, named CA4-dNS1-nCoV-RBD (dNS1-RBD). A preclinical study showed that in hamsters challenged 1 d after single-dose vaccination or 9 months after booster vaccination, dNS1-RBD largely mitigated lung pathology, with no loss of body weight. Moreover, such cellular immunity is relatively unimpaired for the most concerning SARS-CoV-2 variants, especially for the latest Omicron variant. In addition, this vaccine also provides cross-protection against H1N1 and H5N1 influenza viruses. The protective immune mechanism of dNS1-RBD could be attributed to the innate immune response in the nasal epithelium, local RBD-specific T cell response in the lung, and RBD-specific IgA and IgG response. Thus, this study demonstrates that the intranasally delivered dNS1-RBD vaccine candidate may offer an important addition to the fight against the ongoing coronavirus disease 2019 pandemic and influenza infection, compensating limitations of current intramuscular vaccines.

3.
Cell Mol Immunol ; 19(5): 588-601, 2022 May.
Article in English | MEDLINE | ID: covidwho-1830046

ABSTRACT

Live attenuated vaccines might elicit mucosal and sterilizing immunity against SARS-CoV-2 that the existing mRNA, adenoviral vector and inactivated vaccines fail to induce. Here, we describe a candidate live attenuated vaccine strain of SARS-CoV-2 in which the NSP16 gene, which encodes 2'-O-methyltransferase, is catalytically disrupted by a point mutation. This virus, designated d16, was severely attenuated in hamsters and transgenic mice, causing only asymptomatic and nonpathogenic infection. A single dose of d16 administered intranasally resulted in sterilizing immunity in both the upper and lower respiratory tracts of hamsters, thus preventing viral spread in a contact-based transmission model. It also robustly stimulated humoral and cell-mediated immune responses, thus conferring full protection against lethal challenge with SARS-CoV-2 in a transgenic mouse model. The neutralizing antibodies elicited by d16 effectively cross-reacted with several SARS-CoV-2 variants. Secretory immunoglobulin A was detected in the blood and nasal wash of vaccinated mice. Our work provides proof-of-principle evidence for harnessing NSP16-deficient SARS-CoV-2 for the development of live attenuated vaccines and paves the way for further preclinical studies of d16 as a prototypic vaccine strain, to which new features might be introduced to improve safety, transmissibility, immunogenicity and efficacy.


Subject(s)
COVID-19 , SARS-CoV-2 , Administration, Intranasal , Animals , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/prevention & control , COVID-19 Vaccines , Cricetinae , Mice , Mice, Transgenic , Spike Glycoprotein, Coronavirus , Vaccines, Attenuated/genetics
4.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-325084

ABSTRACT

The development of an effective vaccine against SARS-CoV-2, the causative agent of pandemic coronavirus disease-2019 (COVID-19), is a global priority. Here, we present three chimpanzee adenovirus vaccines that express either the full-length spike (ChAdTS-S), or receptor-binding domain (RBD) with two different signal sequences (ChAdTS-RBD and ChAdTS-RBDs). Single-dose intranasal or intramuscular immunization induced robust and sustained neutralizing antibody responses in BALB/c mice, with ChAdTS-S being superior to ChAdTS-RBD and ChAdTS-RBDs. Intranasal immunization appeared to induce a predominately Th2-based response whereas intramuscular administration resulted in a predominately Th1 response. The neutralizing activity against several circulating SARS-CoV-2 variants remained unaffected for mice serum but reduced for rhesus macaque serum. Importantly, immunization with ChAdTS-S via either route induced protective immunity against high-dose challenge with live SARS-CoV-2 in rhesus macaques. Vaccinated macaques demonstrated dramatic decreases in viral RNA in the lungs and nasal swabs, as well as reduced lung pathology compared to the control animals. Similar protective effects were also found in a golden Syrian hamster model of SARS-CoV-2 infection. Taken together, these results confirm that ChAdTS-S can induce protective immune responses in experimental animals, meriting further development toward a human vaccine against SARS-CoV-2.

5.
EBioMedicine ; 75: 103762, 2022 Jan.
Article in English | MEDLINE | ID: covidwho-1587929

ABSTRACT

BACKGROUND: Vaccines in emergency use are efficacious against COVID-19, yet vaccine-induced prevention against nasal SARS-CoV-2 infection remains suboptimal. METHODS: Since mucosal immunity is critical for nasal prevention, we investigated the efficacy of an intramuscular PD1-based receptor-binding domain (RBD) DNA vaccine (PD1-RBD-DNA) and intranasal live attenuated influenza-based vaccines (LAIV-CA4-RBD and LAIV-HK68-RBD) against SARS-CoV-2. FINDINGS: Substantially higher systemic and mucosal immune responses, including bronchoalveolar lavage IgA/IgG and lung polyfunctional memory CD8 T cells, were induced by the heterologous PD1-RBD-DNA/LAIV-HK68-RBD as compared with other regimens. When vaccinated animals were challenged at the memory phase, prevention of robust SARS-CoV-2 infection in nasal turbinate was achieved primarily by the heterologous regimen besides consistent protection in lungs. The regimen-induced antibodies cross-neutralized variants of concerns. Furthermore, LAIV-CA4-RBD could boost the BioNTech vaccine for improved mucosal immunity. INTERPRETATION: Our results demonstrated that intranasal influenza-based boost vaccination induces mucosal and systemic immunity for effective SARS-CoV-2 prevention in both upper and lower respiratory systems. FUNDING: This study was supported by the Research Grants Council Collaborative Research Fund, General Research Fund and Health and Medical Research Fund in Hong Kong; Outbreak Response to Novel Coronavirus (COVID-19) by the Coalition for Epidemic Preparedness Innovations; Shenzhen Science and Technology Program and matching fund from Shenzhen Immuno Cure BioTech Limited; the Health@InnoHK, Innovation and Technology Commission of Hong Kong; National Program on Key Research Project of China; donations from the Friends of Hope Education Fund; the Theme-Based Research Scheme.


Subject(s)
COVID-19 Vaccines , COVID-19/prevention & control , Immunization, Secondary , Influenza Vaccines , SARS-CoV-2 , Vaccines, DNA , Administration, Intranasal , Animals , COVID-19/genetics , COVID-19/immunology , COVID-19 Vaccines/genetics , COVID-19 Vaccines/immunology , Chlorocebus aethiops , Disease Models, Animal , Dogs , Female , HEK293 Cells , Humans , Immunity, Mucosal , Influenza Vaccines/genetics , Influenza Vaccines/immunology , Madin Darby Canine Kidney Cells , Male , Mice , Mice, Inbred BALB C , Mice, Transgenic , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunology , Vaccines, DNA/genetics , Vaccines, DNA/immunology , Vero Cells
7.
Commun Biol ; 4(1): 1102, 2021 09 20.
Article in English | MEDLINE | ID: covidwho-1428909

ABSTRACT

Emerging variants of SARS-CoV-2 have been shown to rapidly replace original circulating strains in humans soon after they emerged. There is a lack of experimental evidence to explain how these natural occurring variants spread more efficiently than existing strains of SARS-CoV-2 in transmission. We found that the Alpha variant (B.1.1.7) increased competitive fitness over earlier parental D614G lineages in in-vitro and in-vivo systems. Using hamster transmission model, we further demonstrated that the Alpha variant is able to replicate and shed more efficiently in the nasal cavity of hamsters than other variants with low dose and short duration of exposure. The capability to initiate effective infection with low inocula may be one of the key factors leading to the rapid transmission of emerging variants of SARS-CoV-2.


Subject(s)
COVID-19/genetics , SARS-CoV-2/genetics , Virus Replication/genetics , Animals , COVID-19/pathology , COVID-19/transmission , Cell Line/virology , Cricetinae , Disease Models, Animal , Humans , SARS-CoV-2/pathogenicity
8.
Nat Commun ; 12(1): 2790, 2021 05 13.
Article in English | MEDLINE | ID: covidwho-1387341

ABSTRACT

SARS-CoV-2 is of zoonotic origin and contains a PRRA polybasic cleavage motif which is considered critical for efficient infection and transmission in humans. We previously reported on a panel of attenuated SARS-CoV-2 variants with deletions at the S1/S2 junction of the spike protein. Here, we characterize pathogenicity, immunogenicity, and protective ability of a further cell-adapted SARS-CoV-2 variant, Ca-DelMut, in in vitro and in vivo systems. Ca-DelMut replicates more efficiently than wild type or parental virus in Vero E6 cells, but causes no apparent disease in hamsters, despite replicating in respiratory tissues. Unlike wild type virus, Ca-DelMut causes no obvious pathological changes and does not induce elevation of proinflammatory cytokines, but still triggers a strong neutralizing antibody and T cell response in hamsters and mice. Ca-DelMut immunized hamsters challenged with wild type SARS-CoV-2 are fully protected, with little sign of virus replication in the upper or lower respiratory tract, demonstrating sterilizing immunity.


Subject(s)
COVID-19/diagnosis , Mutation , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , Virus Replication/genetics , Animals , COVID-19/immunology , COVID-19/virology , Cell Line, Tumor , Chlorocebus aethiops , Cricetinae , Cytokines/immunology , Cytokines/metabolism , Female , Host-Pathogen Interactions , Humans , Male , Mesocricetus , Mice, Inbred BALB C , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , T-Lymphocytes/immunology , T-Lymphocytes/metabolism , Vero Cells , Virulence/genetics , Virulence/immunology
9.
Clin Infect Dis ; 73(2): e437-e444, 2021 07 15.
Article in English | MEDLINE | ID: covidwho-1315658

ABSTRACT

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contains the furin cleavage Proline-Arginine-Arginine-Alanine (PRRA) motif in the S1/S2 region, which enhances viral pathogenicity but is absent in closely related bat and pangolin coronaviruses. Whether bat-like coronaviral variants without PRRA (∆PRRA) can establish natural infections in humans is unknown. METHODS: Here, we developed a duplex digital polymerase chain reaction assay to examine ∆PRRA variants in Vero-E6-propagated isolates, human organoids, experimentally infected hamsters, and coronavirus disease 2019 (COVID-19) patients. RESULTS: We found that SARS-CoV-2, as currently transmitting in humans, contained a quasispecies of wild-type, ∆PRRA variants and variants that have mutations upstream of the PRRA motif. Moreover, the ∆PRRA variants were readily detected despite being at a low intra-host frequency in transmitted founder viruses in hamsters and in COVID-19 patients, including in acute cases and a family cluster, with a prevalence rate of 52.9%. CONCLUSIONS: Our findings demonstrate that bat-like SARS-CoV-2ΔPRRA not only naturally exists but remains transmissible in COVID-19 patients, which has significant implications regarding the zoonotic origin and natural evolution of SARS-CoV-2.


Subject(s)
COVID-19 , Chiroptera , Alanine , Animals , Arginine , Humans , Proline , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/genetics
10.
Front Immunol ; 12: 697074, 2021.
Article in English | MEDLINE | ID: covidwho-1311376

ABSTRACT

The development of a safe and effective vaccine against SARS-CoV-2, the causative agent of pandemic coronavirus disease-2019 (COVID-19), is a global priority. Here, we aim to develop novel SARS-CoV-2 vaccines based on a derivative of less commonly used rare adenovirus serotype AdC68 vector. Three vaccine candidates were constructed expressing either the full-length spike (AdC68-19S) or receptor-binding domain (RBD) with two different signal sequences (AdC68-19RBD and AdC68-19RBDs). Single-dose intramuscular immunization induced robust and sustained binding and neutralizing antibody responses in BALB/c mice up to 40 weeks after immunization, with AdC68-19S being superior to AdC68-19RBD and AdC68-19RBDs. Importantly, immunization with AdC68-19S induced protective immunity against high-dose challenge with live SARS-CoV-2 in a golden Syrian hamster model of SARS-CoV-2 infection. Vaccinated animals demonstrated dramatic decreases in viral RNA copies and infectious virus in the lungs, as well as reduced lung pathology compared to the control animals. Similar protective effects were also found in rhesus macaques. Taken together, these results confirm that AdC68-19S can induce protective immune responses in experimental animals, meriting further development toward a human vaccine against SARS-CoV-2.


Subject(s)
Adenovirus Vaccines/administration & dosage , COVID-19 Vaccines/administration & dosage , COVID-19/prevention & control , Immunization Schedule , Immunogenicity, Vaccine , SARS-CoV-2/immunology , Vaccination/methods , Adenovirus Vaccines/immunology , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/virology , COVID-19 Vaccines/immunology , Cricetinae , Disease Models, Animal , Female , HEK293 Cells , Humans , Male , Mice , Mice, Inbred BALB C , Pan troglodytes , RNA, Viral/blood , Spike Glycoprotein, Coronavirus/immunology , Transfection , Treatment Outcome
11.
Clin Infect Dis ; 72(12): e978-e992, 2021 06 15.
Article in English | MEDLINE | ID: covidwho-1269557

ABSTRACT

BACKGROUND: Clinical outcomes of the interaction between the co-circulating pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and seasonal influenza viruses are unknown. METHODS: We established a golden Syrian hamster model coinfected by SARS-CoV-2 and mouse-adapted A(H1N1)pdm09 simultaneously or sequentially. The weight loss, clinical scores, histopathological changes, viral load and titer, and serum neutralizing antibody titer were compared with hamsters challenged by either virus. RESULTS: Coinfected hamsters had more weight loss, more severe lung inflammatory damage, and tissue cytokine/chemokine expression. Lung viral load, infectious virus titers, and virus antigen expression suggested that hamsters were generally more susceptible to SARS-CoV-2 than to A(H1N1)pdm09. Sequential coinfection with A(H1N1)pdm09 one day prior to SARS-CoV-2 exposure resulted in a lower lung SARS-CoV-2 titer and viral load than with SARS-CoV-2 monoinfection, but a higher lung A(H1N1)pdm09 viral load. Coinfection also increased intestinal inflammation with more SARS-CoV-2 nucleoprotein expression in enterocytes. Simultaneous coinfection was associated with delay in resolution of lung damage, lower serum SARS-CoV-2 neutralizing antibody, and longer SARS-CoV-2 shedding in oral swabs compared to that of SARS-CoV-2 monoinfection. CONCLUSIONS: Simultaneous or sequential coinfection by SARS-CoV-2 and A(H1N1)pdm09 caused more severe disease than monoinfection by either virus in hamsters. Prior A(H1N1)pdm09 infection lowered SARS-CoV-2 pulmonary viral loads but enhanced lung damage. Whole-population influenza vaccination for prevention of coinfection, and multiplex molecular diagnostics for both viruses to achieve early initiation of antiviral treatment for improvement of clinical outcome should be considered.


Subject(s)
COVID-19 , Coinfection , Influenza A Virus, H1N1 Subtype , Influenza, Human , Animals , Cricetinae , Disease Models, Animal , Humans , Mesocricetus , Mice , SARS-CoV-2
12.
Emerg Microbes Infect ; 9(1): 837-842, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-72297

ABSTRACT

The emergence of SARS-CoV-2 has led to the current global coronavirus pandemic and more than one million infections since December 2019. The exact origin of SARS-CoV-2 remains elusive, but the presence of a distinct motif in the S1/S2 junction region suggests the possible acquisition of cleavage site(s) in the spike protein that promoted cross-species transmission. Through plaque purification of Vero-E6 cultured SARS-CoV-2, we found a series of variants which contain 15-30-bp deletions (Del-mut) or point mutations respectively at the S1/S2 junction. Examination of the original clinical specimen from which the isolate was derived, and 26 additional SARS-CoV-2 positive clinical specimens, failed to detect these variants. Infection of hamsters shows that one of the variants (Del-mut-1) which carries deletion of 10 amino acids (30bp) does not cause the body weight loss or more severe pathological changes in the lungs that is associated with wild type virus infection. We suggest that the unique cleavage motif promoting SARS-CoV-2 infection in humans may be under strong selective pressure, given that replication in permissive Vero-E6 cells leads to the loss of this adaptive function. It would be important to screen the prevalence of these variants in asymptomatic infected cases. The potential of the Del-mut variants as an attenuated vaccine or laboratory tool should be evaluated.


Subject(s)
Coronavirus Infections/pathology , Disease Models, Animal , Mesocricetus , Pneumonia, Viral/pathology , SARS Virus/genetics , SARS Virus/pathogenicity , Sequence Deletion , Spike Glycoprotein, Coronavirus/genetics , Amino Acid Sequence , Animals , Base Sequence , COVID-19 , Cell Line , Chlorocebus aethiops , Coronavirus Infections/virology , Female , Host Specificity , Humans , Lung/pathology , Male , Pandemics , Pneumonia, Viral/virology , SARS Virus/growth & development , SARS Virus/isolation & purification , Spike Glycoprotein, Coronavirus/chemistry , Vero Cells , Virulence
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