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1.
The Lancet Regional Health - Western Pacific ; : 100660, 2022.
Article in English | ScienceDirect | ID: covidwho-2165672

ABSTRACT

Summary Background The ongoing outbreak of SARS-CoV-2 Omicron BA.2 infections in Hong Kong, the model city of universal masking of the world, has resulted in a major public health crisis. Although the third vaccination resulted in strong boosting of neutralization antibody, vaccine efficacy and correlate of immune protection against the major circulating Omicron BA.2 remain to be investigated. Methods We investigated the vaccine efficacy against the Omicron BA.2 breakthrough infection among 470 public servants who had received different SARS-CoV-2 vaccine regimens including two-dose BNT162b2 (2 × BNT, n = 169), three-dose BNT162b2 (3 × BNT, n = 168), two-dose CoronaVac (2 × CorV, n = 34), three-dose CoronaVac (3 × CorV, n = 67) and third-dose BNT162b2 following 2 × CorV (2 × CorV+1BNT, n = 32). Humoral and cellular immune responses after three-dose vaccination were further characterized and correlated with clinical characteristics of BA.2 infection. Findings During the BA.2 outbreak, 27.7% vaccinees were infected. The timely third-dose vaccination provided significant protection with lower incidence rates of breakthrough infections (2 × BNT 46.2% vs 3 × BNT 13.1%, p < 0.0001;2 × CorV 44.1% vs 3 × CorV 19.4%, p = 0.003). Investigation of immune responses on blood samples derived from 90 subjects in three-dose vaccination cohorts collected before the BA.2 outbreak revealed that the third-dose vaccination activated spike (S)-specific memory B cells and Omicron cross-reactive T cell responses, which correlated with reduced frequencies of breakthrough infections and disease severity rather than with types of vaccines. Moreover, the frequency of S-specific activated memory B cells was significantly lower in infected vaccinees than uninfected vaccinees before vaccine-breakthrough infection whereas IFN-γ+ CD4 T cells were negatively associated with age and viral clearance time. Critically, BA.2 breakthrough infection boosted cross-reactive memory B cells with enhanced cross-neutralizing antibodies to Omicron sublineages, including BA.2.12.1 and BA.4/5, in all vaccinees tested. Interpretation Our results imply that the timely third vaccination and immune responses are likely required for vaccine-mediated protection against Omicron BA.2 pandemic. Although BA.2 conferred the highest neutralization resistance compared with variants of concern tested before the emergence of BA.2.12.1 and BA.4/5, the third dose vaccination-activated S-specific memory B cells and Omicron cross-reactive T cell responses contributed to reduced frequencies of breakthrough infection and disease severity. Neutralizing antibody potency enhanced by BA.2 breakthrough infection in vaccinees with prior 3 doses of CoronaVac or BNT162b2 may reduce the risk of infection against ongoing BA.2.12.1 and BA.4/5. Funding Hong Kong Research Grants Council Collaborative Research Fund, Health and Medical Research Fund, Wellcome Trust, Shenzhen Science and Technology Program, the Health@InnoHK, Innovation and Technology Commission of Hong Kong, China, National Program on Key Research Project, Emergency Key Program of Guangzhou Laboratory, donations from the Friends of Hope Education Fund and the Hong Kong Theme-Based Research Scheme.

2.
Genes & Diseases ; 2022.
Article in English | ScienceDirect | ID: covidwho-2130871

ABSTRACT

Inactivated COVID-19 vaccines have been widely used to vaccinate the Chinese population. However, limited literature exists to explore the effect of obesity on the humoral and cellular immune response to these vaccines. In this study, 132 high BMI (Body mass index) (obesity and overweight, BMI ≥ 24 kg/m2) and 82 normal BMI (BMI < 24 kg/m2) participants were enrolled. Adverse events (AEs), Spike receptor-binding domain IgG antibody (anti-RBD-IgG), neutralizing antibodies (NAbs), and specific B-cell and T-cell responses were evaluated 21-105 days after full-course inactivated COVID-19 vaccination. The overall incidence of adverse events (AEs) was similar in individuals with and without obesity/overweight. No serious vaccine-related AEs occurred. Individuals with obesity/overweight had a reduced seropositivity rate of NAbs compared to those with normal BMI. Anti-RBD-IgG and NAbs titers in the high BMI group were significantly lower than those in the normal BMI group. The frequencies of RBD-specific memory B cells (MBCs) and the numbers of spike-specific TNF-α+ spot-forming cells (SFCs) in individuals with obesity/overweight were reduced compared with those noted in individuals without obesity/overweight. A similar trend of weakened humoral responses was also observed in individuals with central obesity. Our study results suggested that inactivated COVID-19 vaccines were safe and well tolerated but induced poor humoral and cellular immune responses in Chinese individuals with obesity/overweight.

3.
Emerg Microbes Infect ; : 1-52, 2022 Nov 10.
Article in English | MEDLINE | ID: covidwho-2107219

ABSTRACT

Increasing spread by SARS-CoV-2 Omicron variants challenges existing vaccines and broadly reactive neutralizing antibodies (bNAbs) against COVID-19. Here we determine the diversity, potency, breadth and structural insights of bNAbs derived from memory B cells of BNT162b2-vaccinee after homogeneous Omicron BA.1 breakthrough infection. The infection activates diverse memory B cell clonotypes for generating potent class I/II or III bNAbs with new epitopes mapped to receptor-binding domain (RBD). The top eight bNAbs neutralize wildtype and BA.1 potently but display divergent IgH/IgL sequences and neuralization profiles against other variants of concern (VOCs). Two of them (P2D9 and P3E6) belonging to class III NAbs display comparable potency against BA.4/BA.5, although structural analysis reveals distinct modes of action. P3E6 neutralizes all variants tested through a unique bivalent interaction with two RBDs. Our findings provide new insights into hybrid immunity on BNT162b2-induced diverse memory B cells in response to Omicron breakthrough infection for generating diverse bNAbs with distinct structural basis.

5.
Front Immunol ; 13: 988004, 2022.
Article in English | MEDLINE | ID: covidwho-2080152

ABSTRACT

The antibody and B cell responses after inactivated SARS-CoV-2 vaccination have not been well documented in patients with autoimmune liver disease (AILD). Therefore, we conducted a prospective observational study that included AILD patients and healthy participants as controls between July 1, 2021, and September 30, 2021, at the Second Affiliated Hospital of Chongqing Medical University. All adverse events (AEs) after the COVID-19 vaccination were recorded and graded. Immunoglobulin (Ig)-G antibodies against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein (anti-RBD-IgG) and neutralizicadng antibodies (NAbs) were tested following full-course vaccination (BBIBP-CorV or CoronaVac). In addition, SARS-CoV-2-specific B cells were detected by flow cytometry. In total, 76 AILD patients and 136 healthy controls (HCs) were included. All AEs were mild and self-limiting, and the incidences were similar between the AILD and HCs. The seropositivity rates of anti-RBD-IgG and NAbs in AILD were 97.4% (100% in HCs, p = 0.13) and 63.2% (84.6% in HCs, p < 0.001), respectively. The titers of anti-RBD-IgG and NAbs were significantly lower in AILD patients than those in HCs. After adjusting for confounders, immunosuppressive therapy was an independent risk factor for low-level anti-RBD-IgG (adjusted odds ratio [aOR]: 4.7; 95% confidence interval [CI], 1.5-15.2; p = 0.01) and a reduced probability of NAbs seropositivity (aOR, 3.0; 95% CI, 1.0-8.9; p = 0.04) in AILD patients. However, regardless of immunosuppressants, the SARS-CoV-2-specific memory B cells responses were comparable between the AILD and HC groups. Our results suggest that inactivated SARS-CoV-2 vaccines (BBIBP-CorV and CoronaVac) are safe, but their immunogenicity is compromised in patients with AILD. Moreover, immunosuppressants are significantly associated with poor antibody responses to the SARS-CoV-2 vaccines. These results could inform physicians and policymakers about decisions on screening the populations at higher risk of poor antibody responses to SARS-CoV-2 vaccines and providing additional vaccinations in patients with AILD.


Subject(s)
Autoimmune Diseases , COVID-19 , Liver Diseases , Humans , COVID-19 Vaccines/adverse effects , SARS-CoV-2 , Immunosuppressive Agents/adverse effects , Antibody Formation , Antibodies, Viral , Immunoglobulin G
6.
Cell Mol Immunol ; 19(11): 1302-1310, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2062196

ABSTRACT

Mutations in SARS-CoV-2 variants of concern (VOCs) have enhanced transmissibility and immune evasion with respect to current vaccines and neutralizing antibodies (NAbs). How naturally occurring spike mutations affect the infectivity and antigenicity of VOCs remains to be investigated. The entry efficiency of individual spike mutations was determined in vitro using pseudotyped viruses. BALB/c mice were immunized with 2-dose DNA vaccines encoding B.1.1.7, B.1.351, B.1.1.529  and their single mutations. Cellular and humoral immune responses were then compared to determine the impact of individual mutations on immunogenicity. In the B.1.1.7 lineage, Del69-70 and Del 144 in NTD, A570D and P681H in SD1 and S982A and D1118H in S2 significantly increased viral entry, whereas T716I resulted in a decrease. In the B.1.351 lineage, L18F and Del 242-244 in the NTD, K417N in the RBD and A701V in S2 also increased viral entry. S982A weakened the generation of binding antibodies. All sera showed reduced cross-neutralization activity against B.1.351, B.1.617.2 (Delta) and B.1.1.529 (Omicron BA.1). S982A, L18F, and Del 242-244 hindered the induction of cross-NAbs, whereas Del 69-70, Del144, R246I, and K417N showed the opposite effects. B.1.351 elicited adequate broad cross-NAbs against both B.1.351 and B.1.617.2. All immunogens tested, however, showed low neutralization against circulating B.1.1.529. In addition, T-cell responses were unlikely affected by mutations tested in the spike. We conclude that individual spike mutations influence viral infectivity and vaccine immunogenicity. Designing VOC-targeted vaccines is likely necessary to overcome immune evasion from current vaccines and neutralizing antibodies.


Subject(s)
COVID-19 , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Animals , Humans , Mice , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/immunology , COVID-19/virology , Mice, Inbred BALB C , Mutation , Neutralization Tests , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology
7.
Frontiers in psychology ; 13, 2022.
Article in English | EuropePMC | ID: covidwho-2047100

ABSTRACT

Online education has advantages during COVID-19, but it also has problems related to hardware support and user experience. Focusing on teaching quality by discipline is an effective way to improve teaching quality in universities. To investigate the online education experience from the perspective of different academic disciplines, we evaluated 251,929 student questionnaires and 13,695 teacher questionnaires from 334 universities in China. The main finding was a difference in teaching preparation, experience, feedback, and improvement processes by disciplines. Teachers and students had obvious disciplinary differences in preparation, school support, and teaching constraints. However, disciplinary differences were minor for pedagogical issues such as participation, assignments, and grading, as well as for evaluation of platform technical support and views on the continuation of online learning. The research results analyzed the teaching psychology of teachers and students in different disciplines during the pandemic. Therefore, it explained the impact and role of discipline differences on students’ learning psychology during COVID-19. This research will benefit educators, researchers, and policy makers to help them with the improvement of online education.

8.
Clin Transl Med ; 12(9): e1025, 2022 09.
Article in English | MEDLINE | ID: covidwho-2027333

ABSTRACT

BACKGROUND: Patients with COVID-19 display a broad spectrum of manifestations from asymptomatic to life-threatening disease with dysregulated immune responses. Mechanisms underlying the detrimental immune responses and disease severity remain elusive. METHODS: We investigated a total of 137 APs infected with SARS-CoV-2. Patients were divided into mild and severe patient groups based on their requirement of oxygen supplementation. All blood samples from APs were collected within three weeks after symptom onset. Freshly isolated PBMCs were investigated for B cell subsets, their homing potential, activation state, mitochondrial functionality and proliferative response. Plasma samples were tested for cytokine concentration, and titer of Nabs, RBD-, S1-, SSA/Ro- and dsDNA-specific IgG. RESULTS: While critically ill patients displayed predominantly extrafollicular B cell activation with elevated inflammation, mild patients counteracted the disease through the timely induction of mitochondrial dysfunction in B cells within the first week post symptom onset. Rapidly increased mitochondrial dysfunction, which was caused by infection-induced excessive intracellular calcium accumulation, suppressed excessive extrafollicular responses, leading to increased neutralizing potency index and decreased inflammatory cytokine production. Patients who received prior COVID-19 vaccines before infection displayed significantly decreased extrafollicular B cell responses and mild disease. CONCLUSION: Our results reveal an immune mechanism that controls SARS-CoV-2-induced detrimental B cell responses and COVID-19 severity, which may have implications for viral pathogenesis, therapeutic interventions and vaccine development.


Subject(s)
COVID-19 , Viral Vaccines , B-Lymphocytes , COVID-19 Vaccines , Cytokines , Humans , Mitochondria , SARS-CoV-2 , Severity of Illness Index , Viral Vaccines/pharmacology
9.
Microchem J ; 182: 107866, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-1983668

ABSTRACT

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2) is a cluster of ß coronaviruses. The 2019 coronavirus disease (COVID-19) caused by SARS-COV-2 is emerging as a global pandemic. Thus, early diagnosis of SARS-COV-2 is essential to prevent severe outbreaks of the disease. In this experiment, a novel label-free photoelectrochemical (PEC) immunosensor was obtained based on silver sulfide (Ag2S) sensitized titanium dioxide@bismuth tungstate (TiO2@Bi2WO6) nanocomposite for quantitative detection of SARS-COV-2 nucleocapsid protein. The constructed TiO2@Bi2WO6 hollow microspheres had large specific surface area and could produce high photocurrent intensity under visible light illumination. Ag2S was in-situ grown on the surface of thioglycolic acid (TGA) modified TiO2@Bi2WO6. In particular, TiO2@Bi2WO6 and Ag2S formed a good energy level match, which could effectively enhance the photocurrent conversion efficiency and strength the photocurrent response. Ascorbic acid (AA) acted as an effective electron donor to effectively eliminate photogenerated holes. Under optimal experimental conditions, the constructed immunosensor presented a supersensitive response to SARS-COV-2 nucleocapsid protein, with a desirable linear relationship ranged from 0.001 to 50 ng/mL for nucleocapsid protein and a lower detection limit of 0.38 pg/mL. The fabricated sensor exhibited a wide linear range, excellent selectivity, specificity and stability, which provided a valuable referential idea for the detection of SARS-COV-2.

10.
Phytother Res ; 36(8): 3232-3247, 2022 Aug.
Article in English | MEDLINE | ID: covidwho-1976773

ABSTRACT

The current COVID-19 pandemic caused by SARS-Cov-2 is responsible for more than 6 million deaths globally. The development of broad-spectrum and cost-effective antivirals is urgently needed. Medicinal plants are renowned as a complementary approach in which antiviral natural products have been established as safe and effective drugs. Here, we report that the percolation extract of Spatholobus suberectus Dunn (SSP) is a broad-spectrum viral entry inhibitor against SARS-CoV-1/2 and other enveloped viruses. The viral inhibitory activities of the SSP were evaluated by using pseudotyped SARS-CoV-1 and 2, HIV-1ADA and HXB2 , and H5N1. SSP effectively inhibited viral entry and with EC50 values ranging from 3.6 to 5.1 µg/ml. Pre-treatment of pseudovirus or target cells with SSP showed consistent inhibitory activities with the respective EC50 value of 2.3 or 2.1 µg/ml. SSP blocked both SARS-CoV-2 spike glycoprotein and the host ACE2 receptor. In vivo studies indicated that there was no abnormal toxicity and behavior in long-term SSP treatment. Based on these findings, we concluded that SSP has the potential to be developed as a drug candidate for preventing and treating COVID-19 and other emerging enveloped viruses.


Subject(s)
COVID-19 , Influenza A Virus, H5N1 Subtype , Antiviral Agents/pharmacology , COVID-19/drug therapy , Humans , Pandemics/prevention & control , SARS-CoV-2
11.
Cell Discov ; 8(1): 57, 2022 Jun 17.
Article in English | MEDLINE | ID: covidwho-1967594

ABSTRACT

The airways and alveoli of the human respiratory tract are lined by two distinct types of epithelium, which are the primary targets of respiratory viruses. We previously established long-term expanding human lung epithelial organoids from lung tissues and developed a 'proximal' differentiation protocol to generate mucociliary airway organoids. However, a respiratory organoid system with bipotential of the airway and alveolar differentiation remains elusive. Here we defined a 'distal' differentiation approach to generate alveolar organoids from the same source for the derivation of airway organoids. The alveolar organoids consisting of type I and type II alveolar epithelial cells (AT1 and AT2, respectively) functionally simulate the alveolar epithelium. AT2 cells maintained in lung organoids serve as progenitor cells from which alveolar organoids derive. Moreover, alveolar organoids sustain a productive SARS-CoV-2 infection, albeit a lower replicative fitness was observed compared to that in airway organoids. We further optimized 2-dimensional (2D) airway organoids. Upon differentiation under a slightly acidic pH, the 2D airway organoids exhibit enhanced viral replication, representing an optimal in vitro correlate of respiratory epithelium for modeling the high infectivity of SARS-CoV-2. Notably, the higher infectivity and replicative fitness of the Omicron variant than an ancestral strain were accurately recapitulated in these optimized airway organoids. In conclusion, we have established a bipotential organoid culture system able to reproducibly expand the entire human respiratory epithelium in vitro for modeling respiratory diseases, including COVID-19.

12.
Int J Biol Sci ; 18(12): 4781-4791, 2022.
Article in English | MEDLINE | ID: covidwho-1954684

ABSTRACT

Rapid development and successful use of vaccines against SARS-CoV-2 might hold the key to curb the ongoing pandemic of COVID-19. Emergence of vaccine-evasive SARS-CoV-2 variants of concern (VOCs) has posed a new challenge to vaccine design and development. One urgent need is to determine what types of variant-specific and bivalent vaccines should be developed. Here, we compared homotypic and heterotypic protection against SARS-CoV-2 infection of hamsters with monovalent and bivalent whole-virion inactivated vaccines derived from representative VOCs. In addition to the ancestral SARS-CoV-2 Wuhan strain, Delta (B.1.617.2; δ) and Theta (P.3; θ) variants were used in vaccine preparation. Additional VOCs including Omicron (B.1.1.529) and Alpha (B.1.1.7) variants were employed in the challenge experiment. Consistent with previous findings, Omicron variant exhibited the highest degree of immune evasion, rendering all different forms of inactivated vaccines substantially less efficacious. Notably, monovalent and bivalent Delta variant-specific inactivated vaccines provided optimal protection against challenge with Delta variant. Yet, some cross-variant protection against Omicron and Alpha variants was seen with all monovalent and bivalent inactivated vaccines tested. Taken together, our findings support the notion that an optimal next-generation inactivated vaccine against SARS-CoV-2 should contain the predominant VOC in circulation. Further investigations are underway to test whether a bivalent vaccine for Delta and Omicron variants can serve this purpose.


Subject(s)
COVID-19 , Viral Vaccines , Animals , COVID-19/prevention & control , COVID-19 Vaccines , Cricetinae , Humans , SARS-CoV-2 , Vaccines, Combined , Vaccines, Inactivated
13.
Nature ; 608(7923): 603-608, 2022 08.
Article in English | MEDLINE | ID: covidwho-1921637

ABSTRACT

SARS-CoV-2 Omicron subvariants BA.2.12.1 and BA.4/5 have surged notably to become dominant in the United States and South Africa, respectively1,2. These new subvariants carrying further mutations in their spike proteins raise concerns that they may further evade neutralizing antibodies, thereby further compromising the efficacy of COVID-19 vaccines and therapeutic monoclonals. We now report findings from a systematic antigenic analysis of these surging Omicron subvariants. BA.2.12.1 is only modestly (1.8-fold) more resistant to sera from vaccinated and boosted individuals than BA.2. However, BA.4/5 is substantially (4.2-fold) more resistant and thus more likely to lead to vaccine breakthrough infections. Mutation at spike residue L452 found in both BA.2.12.1 and BA.4/5 facilitates escape from some antibodies directed to the so-called class 2 and 3 regions of the receptor-binding domain3. The F486V mutation found in BA.4/5 facilitates escape from certain class 1 and 2 antibodies but compromises the spike affinity for the viral receptor. The R493Q reversion mutation, however, restores receptor affinity and consequently the fitness of BA.4/5. Among therapeutic antibodies authorized for clinical use, only bebtelovimab retains full potency against both BA.2.12.1 and BA.4/5. The Omicron lineage of SARS-CoV-2 continues to evolve, successively yielding subvariants that are not only more transmissible but also more evasive to antibodies.


Subject(s)
Antibodies, Viral , Antigenic Drift and Shift , COVID-19 , Mutation , SARS-CoV-2 , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/therapeutic use , Antibodies, Viral/immunology , Antibodies, Viral/therapeutic use , Antigenic Drift and Shift/genetics , Antigenic Drift and Shift/immunology , COVID-19/immunology , COVID-19/virology , COVID-19 Vaccines/immunology , Humans , Immunization, Secondary , Receptors, Virus/metabolism , SARS-CoV-2/classification , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism
15.
Nat Commun ; 13(1): 3589, 2022 Jun 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
17.
Financ Res Lett ; 47: 102781, 2022 Jun.
Article in English | MEDLINE | ID: covidwho-1878170

ABSTRACT

This study estimates the financial costs imposed by political polarization among citizens on U.S. local governments during the COVID-19 pandemic. We measure local political polarization by using citizens' voting results in the presidential elections. We find local political polarization leads to higher offering yield of the bonds issued by the U.S. municipalities. The impact on borrowing costs is exaggerated by the number of pandemic cases in the local area, suggesting political polarization hinders the making and enforcement of government measures for the pandemic. This study highlights the mechanisms through which financial markets and local political ideology jointly affect social welfare.

19.
EBioMedicine ; 77: 103904, 2022 Mar.
Article in English | MEDLINE | ID: covidwho-1867071

ABSTRACT

BACKGROUND: Nearly 4 billion doses of the BNT162b2-mRNA and CoronaVac-inactivated vaccines have been administrated globally, yet different vaccine-induced immunity against SARS-CoV-2 variants of concern (VOCs) remain incompletely investigated. METHODS: We compare the immunogenicity and durability of these two vaccines among fully vaccinated Hong Kong people. FINDINGS: Standard BNT162b2 and CoronaVac vaccinations were tolerated and induced neutralizing antibody (NAb) (100% and 85.7%) and spike-specific CD4 T cell responses (96.7% and 82.1%), respectively. The geometric mean NAb IC50 and median frequencies of reactive CD4 subsets were consistently lower among CoronaVac-vaccinees than BNT162b2-vaccinees. CoronaVac did not induce measurable levels of nucleocapsid protein-specific IFN-γ+ CD4+ T or IFN-γ+ CD8+ T cells compared with unvaccinated. Against VOCs, NAb response rates and geometric mean IC50 titers against B.1.617.2 (Delta) and B.1.1.529 (Omicron) were significantly lower for CoronaVac (50%, 23.2 and 7.1%, <20) than BNT162b2 (94.1%, 131 and 58.8%, 35.0), respectively. Three months after vaccinations, NAbs to VOCs dropped near to detection limit, along with waning memory T cell responses, mainly among CoronaVac-vaccinees. INTERPRETATION: Our results indicate that vaccinees especially CoronaVac-vaccinees with significantly reduced NAbs may probably face higher risk to pandemic VOCs breakthrough infection. FUNDING: This study was supported by the Hong Kong Research Grants Council Collaborative Research Fund (C7156-20GF and C1134-20GF); the Wellcome Trust (P86433); the National Program on Key Research Project of China (Grant 2020YFC0860600, 2020YFA0707500 and 2020YFA0707504); Shenzhen Science and Technology Program (JSGG20200225151410198 and JCYJ20210324131610027); HKU Development Fund and LKS Faculty of Medicine Matching Fund to AIDS Institute; Hong Kong Innovation and Technology Fund, Innovation and Technology Commission and generous donation from the Friends of Hope Education Fund. Z.C.'s team was also partly supported by the Theme-Based Research Scheme (T11-706/18-N).


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing , Antibodies, Viral , CD8-Positive T-Lymphocytes , COVID-19/epidemiology , COVID-19/prevention & control , Hong Kong/epidemiology , Humans , Immunity , SARS-CoV-2/genetics , Vaccination
20.
Cell Mol Immunol ; 19(5): 588-601, 2022 05.
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
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