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1.
Immun Inflamm Dis ; 10(4): e592, 2022 04.
Article in English | MEDLINE | ID: covidwho-1763237

ABSTRACT

BACKGROUND: To understand the kinetics of immune responses with different dosing gaps of the AZD1222 vaccine, we compared antibody and T cell responses in two cohorts with two different dosing gaps. METHODS: Antibodies to the SARS-CoV-2 virus were assessed in 297 individuals with a dosing gap of 12 weeks, sampled 12 weeks post second dose (cohort 1) and in 77 individuals with a median dosing gap of 21.4 weeks (cohort 2) sampled 6 weeks post second dose. ACE2-blocking antibodies (ACE2-blocking Abs), antibodies to the receptor-binding domain (RBD) of  variants of concern (VOC), and ex vivo T cell responses were assessed in a subcohort. RESULTS: All individuals (100%) had SARS-CoV-2-specific total antibodies and 94.2% of cohort 1 and 97.1% of cohort 2 had ACE2-blocking Abs. There was no difference in antibody titers or positivity rates in different age groups in both cohorts. The ACE2-blocking Abs (p < .0001) and antibodies to the RBD of the VOCs were significantly higher in cohort 2 compared to cohort 1. 41.2% to 65.8% of different age groups gave a positive response by the hemagglutination assay to the RBD of the ancestral virus and VOCs in cohort 1, while 53.6%-90% gave a positive response in cohort 2. 17/57 (29.8%) of cohort 1 and 17/29 (58.6%) of cohort 2 had ex vivo interferon (IFN)γ ELISpot responses above the positive threshold. The ACE2-blocking antibodies (Spearman's r = .46, p = .008) and ex vivo IFNγ responses (Spearman's r = .71, p < .0001) at 12 weeks post first dose, significantly correlated with levels 12 weeks post second dose. CONCLUSIONS: Both dosing schedules resulted in high antibody and T cell responses post vaccination, although those with a longer dosing gap had a higher magnitude of responses, possibly as immune responses were measured 6 weeks post second dose compared to 12 weeks post second dose.


Subject(s)
COVID-19 , Vaccines , Antibodies, Viral , COVID-19/prevention & control , Humans , Immunity , Kinetics , SARS-CoV-2 , Sri Lanka
2.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-322889

ABSTRACT

Serological detection of antibodies to SARS-CoV-2 is essential for establishing rates ofseroconversion in populations, and for seeking evidence for a level of antibody that may beprotective against COVID-19 disease. Several high-performance commercial tests have beendescribed, but these require centralised laboratory facilities that are comparativelyexpensive, and therefore not available universally. Red cell agglutination tests do notrequire special equipment, are read by eye, have short development times, low cost and canbe applied at the Point of Care. We describe a quantitative Haemagglutination test (HAT) forthe detection of antibodies to the receptor binding domain of the SARS-CoV-2 spike protein.The HAT has a sensitivity of 90% and specificity of 99% for detection of antibodies after aPCR diagnosed infection. We will supply aliquots of the test reagent sufficient for tenthousand test wells free of charge to qualified research groups anywhere in the world.

3.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-321742

ABSTRACT

Both natural infection with SARS-CoV-2 and immunization with a number of vaccines induce protective immunity. However, the ability of such immune responses to recognize and therefore protect against emerging variants is a matter of increasing importance. Such variants of concern (VOC) include isolates of lineage B1.1.7, first identified in the UK, and B1.351, first identified in South Africa. Our data confirm that VOC, particularly those with substitutions at residues 484 and 417 escape neutralization by antibodies directed to the ACE2-binding Class 1 and the adjacent Class 2 epitopes but are susceptible to neutralization by the generally less potent antibodies directed to Class 3 and 4 epitopes on the flanks RBD. To address this potential threat, we sampled a SARS-CoV-2 uninfected UK cohort recently vaccinated with BNT162b2 (Pfizer-BioNTech, two doses delivered 18-28 days apart), alongside a cohort naturally infected in the first wave of the epidemic in Spring 2020. We tested antibody and T cell responses against a reference isolate (VIC001) representing the original circulating lineage B and the impact of sequence variation in these two VOCs. We identified a reduction in antibody neutralization against the VOCs which was most evident in the B1.351 variant. However, the majority of the T cell response was directed against epitopes conserved across all three strains. The reduction in antibody neutralization was less marked in post-boost vaccine-induced than in naturally-induced immune responses and could be largely explained by the potency of the homotypic antibody response. However, after a single vaccination, which induced only modestly neutralizing homotypic antibody titres, neutralization against the VOCs was completely abrogated in the majority of vaccinees. These data indicate that VOCs may evade protective neutralising responses induced by prior infection, and to a lesser extent by immunization, particularly after a single vaccine, but the impact of the VOCs on T cell responses appears less marked. The results emphasize the need to generate high potency immune responses through vaccination in order to provide protection against these and other emergent variants. We observed that two doses of vaccine also induced a significant increase in binding antibodies to spike of both SARS-CoV-1 & MERS, in addition to the four common coronaviruses currently circulating in the UK. The impact of antigenic imprinting on the potency of humoral and cellular heterotypic protection generated by the next generation of variant-directed vaccines remains to be determined.

4.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-321741

ABSTRACT

Both natural infection with SARS-CoV-2 and immunization with vaccines induce protective immunity. However, the extent to which such immune responses protect against emerging variants is of increasing importance. Such variants of concern (VOC) include isolates of lineage B.1.1.7, first identified in the UK, and B.1.351, first identified in South Africa. Our data confirm that VOC, particularly those with substitutions at residues 484 and 417, escape neutralization by antibodies directed to the ACE2-binding Class 1 and the adjacent Class 2 epitopes but are susceptible to neutralization by the generally less potent antibodies directed to Class 3 and 4 epitopes on the flanks of the receptor-binding domain. To address the potential threat posed by VOC, we sampled a SARS-CoV-2 uninfected UK cohort recently vaccinated with BNT162b2 (Pfizer-BioNTech, two doses delivered 18-28 days apart), alongside a cohort sampled in the early convalescent stages after natural infection in the first wave of the pandemic in Spring 2020. We tested antibody and T cell responses against a reference isolate of the original circulating lineage, B, and the impact of sequence variation in the B.1.1.7 and B.1.351 VOC. Neutralization of the VOC compared to B isolate was reduced, and this was most evident for the B.1.351 isolate. This reduction in antibody neutralization was less marked in post-boost vaccine-induced responses compared to naturally induced immune responses and could be largely explained by the potency of the homotypic antibody response. After a single vaccination, which induced only modestly neutralizing homotypic antibody titres, neutralization against the VOC was completely abrogated in the majority of vaccinees. Importantly, high magnitude T cell responses were generated after two vaccine doses, with the majority of the T cell response directed against epitopes that are conserved between the prototype isolate B and the VOC. These data indicate that VOC may evade protective neutralizing responses induced by prior infection, and to a lesser extent by immunization, particularly after a single vaccine dose, but the impact of the VOC on T cell responses appears less marked. The results emphasize the need to generate high potency immune responses through vaccination in order to provide protection against these and other emergent variants.

5.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-313281

ABSTRACT

Background: As the first dose of Sputnik V Gam-COVID-Vac, is currently used as a single dose vaccine in some countries, we investigated the immunogenicity of a single dose of this vaccine in Sri Lankan adults at 4 weeks and compared the immune responses with our previously published data following AZD1222.Methods: SARS-CoV-2 antibodies were assessed at 504 individuals at the time of recruitment and at 4 weeks since receiving the single dose in Sri Lankan adults. ACE2 receptor blocking antibodies, antibodies to the receptor binding domain (RBD) of variants of concern, ex vivo IFNγ ELISpot responses, intracellular cytokine assays and B cell ELISpot assays were carried out in a sub-cohort.Findings: Of the 327/504 individuals who were baseline seronegative, 88.7% seroconverted, with significantly lower seroconversion rates in those >60-years old (p-value = 0.004) and significantly lower than previously seen with AZD1222 (p=0.018). 82.6% developed ACE2 receptor blocking antibodies, although the levels were significantly lower than seen following natural infection (p=0.0009) and following a single dose of AZD1222 (p<0.0001). Similar titres of antibodies were observed to the RBD of the WT, B.1.1.7 and B.1.617.2 compared to AZD1222, while the levels for B.1.351 were significantly higher (p=0.006) for Gam-COVID-Vac. 30% of individuals developed ex vivo IFNγ ELISpot responses, and high frequency of CD107a expressing T cells along with memory B cell responses. The ex vivo IFNγ responses for spike protein were significantly higher (p<0.0001) for AZD1222 than for Gam-COVID-Vac.Interpretation: A single dose of Sputnik V Gam-COVID-Vac induced high seroconversion rates although lower responses in older age groups in Sri Lankan adults. The overall antibody responses, ACE2 receptor blocking antibody responses and ex vivo T cell responses appear to be significantly lower than previously seen with AZD1222, and so there is likely to be benefit from delivery of the second dose.Funding: We are grateful to the World Health Organization, UK Medical Research Council. theForeign and Commonwealth Office and NIH, USA (grant number 5U01AI151788-02) for support.T.K.T. is funded by the Townsend-Jeantet Charitable Trust (charity number 1011770) and the EPACephalosporin Early Career Researcher Fund.Declaration of Interest: None of the authors have any conflicts of interest.Ethical Approval: Ethics approval was obtained from the Ethics Review Committee of University of Sri Jayewardenepura (COVID 01/21).

6.
EuropePMC; 2020.
Preprint in English | EuropePMC | ID: ppcovidwho-312806

ABSTRACT

The SARS-CoV-2 virus is more transmissible than previous coronaviruses and causes a more serious illness than seasonal flu. The SARS-CoV-2 receptor binding domain (RBD) of the Spike protein binds to the human angiotensin-converting enzyme 2 (ACE2) receptor as a prelude to viral entry into the cell. Using a naïve llama single chain nanobody library and PCR maturation we have produced a nanobody, H11-D4, with a KD 9 nM for RBD that blocks the binding of RBD to the ACE2. Single particle cryo-electron microscopy revealed that H11-D4 binds to each of the three RBDs in the Spike trimer. The 1.8 Å crystal structure of the H11-D4 – RBD complex has illuminated the molecular interactions that drive the high affinity. H11-D4 binds to an epitope on RBD that overlaps with the ACE2 binding, explaining the blocking of ACE2 binding. The nanobody showed potent neutralising activity against live SARS-CoV-2 virus.

8.
Sci Rep ; 12(1): 1727, 2022 02 02.
Article in English | MEDLINE | ID: covidwho-1671625

ABSTRACT

As the first dose of Gam-COVID-Vac, is currently used as a single dose vaccine in some countries, we investigated the immunogenicity of this at 4 weeks (327 naïve individuals). 88.7% seroconverted, with significantly lower seroconversion rates in those over 60 years (p = 0.004) and significantly lower than previously seen with AZD1222 (p = 0.018). 82.6% developed ACE2 receptor blocking antibodies, although levels were significantly lower than following natural infection (p = 0.0009) and a single dose of AZD1222 (p < 0.0001). Similar titres of antibodies were observed to the receptor binding domain of WT, B.1.1.7 and B.1.617.2 compared to AZD1222, while the levels for B.1.351 were significantly higher (p = 0.006) for Gam-COVID-Vac. 30% developed ex vivo IFNγ ELISpot responses (significantly lower than AZD1222), and high frequency of CD107a expressing T cells along with memory B cell responses. Although single dose of Gam-COVID-Vac was highly immunogenic, administration of a second dose is likely to be beneficial.


Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19 Vaccines/administration & dosage , COVID-19/prevention & control , Immunization , Immunogenicity, Vaccine , SARS-CoV-2/immunology , Vaccines, Synthetic/administration & dosage , Adult , Aged , Aged, 80 and over , Angiotensin-Converting Enzyme 2/immunology , Biomarkers/blood , COVID-19/immunology , COVID-19/virology , COVID-19 Vaccines/immunology , Female , Humans , Interferon-gamma/metabolism , Lymphocytes/immunology , Lymphocytes/metabolism , Lymphocytes/virology , Male , Middle Aged , Seroconversion , Time Factors , Treatment Outcome , Vaccines, Synthetic/immunology , Young Adult
10.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-296735

ABSTRACT

We assessed antibody responses 3 months post-vaccination in those who received mRNA-1273 (n=225), Sputnik V (n=128) or the first dose of Gam-COVID-Vac (n=184) and compared the results with previously reported data of Sinopharm and AZD1222 vaccinees. 99.5% of Moderna >94% of AZD1222 or Sputnik V, 72% to 76% of Gam-COVID-Vac (first dose) and 38.1% to 68.3% of Sinopharm vaccinees had ACE2 blocking antibodies above the positive threshold. The ACE2 blocking antibody levels were highest to lowest was Moderna > Sputnik V/ AZD1222 (had equal levels)> first dose of Gam-COVID-Vac > Sinopharm. All Moderna recipients had antibodies above the positive threshold to the ancestral (WT), B.1.1.7, B.1.351.1 and 80% positivity rate for B.1.617.2. Positivity rates of Sputnik V vaccinees for WT and variants, were higher than AZD1222 vaccinees, while Sinopharm vaccinees had the lowest positivity rates (<16.7%). These findings highlight the need for further studies to understand the effects on clinical outcomes.

11.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-295043

ABSTRACT

Background To determine the kinetics and persistence of immune responses following the Sinopharm/BBIBP-CorV, we investigated immune responses in a cohort of Sri Lankan individuals. Methods SARS-CoV-2 specific total antibodies were measured in 20-to-39 year (n=61), 40-to-59-year and those >60 years of age (n=22) by ELISA, 12 weeks after the second dose of the vaccine. ACE2 receptor blocking antibodies (ACE2R-Ab), antibodies to the receptor binding domain (RBD) of the ancestral virus (WT) and variants of concern, were measured in a sub cohort. T cell responses and memory B cell responses were assessed by ELISpot assays. Results 193/203 (95.07%) of individuals had detectable SARS-CoV-2 specific total antibodies, while 67/110 (60.9%) had ACE2R-Ab. 14.3% to 16.7% individuals in the 20 to 39 age groups had detectable antibodies to the RBD of the WT and VOC, while the positivity rates of those >60 years of age was <10%. 14/49 (28.6%) had IFN γ ELISpot responses to overlapping peptides of the spike protein, while memory B cell responses were detected in 9/20 to the S1 recombinant protein. The total antibody levels and ACE2R-Ab declined after 2 to 12 weeks from the second dose, while ex vivo T cell responses remained unchanged. The decline in ACE2R-Ab levels was significant among the 40 to 59 (p=0.0007) and ≥60 (p=0.005) age groups. Conclusions Antibody responses declined in all age groups, especially in those >60 years, while T cell responses persisted. The effect of waning of immunity on hospitalization and severe disease should be assessed by long term efficacy studies.

12.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-294661

ABSTRACT

Evaluation of susceptibility to emerging SARS-CoV-2 variants of concern (VOC) requires rapid screening tests for neutralising antibodies which provide protection. We developed a receptor-binding domain specific hemagglutination test (HAT) which correlated with neutralising antibodies (R=0.74-0.82) in two independent cohorts from 798 convalescents. Home-dwelling older individuals (80-99 years, n=89) had significantly lower antibodies after one dose of BNT162b2 vaccine than younger adult vaccinees (n=310) and naturally infected individuals (n=307). The second vaccine dose boosted and broadened the antibody repertoire to VOC in naïve but not previously infected, older and younger adults. >75% of older adults responded after two vaccinations to alpha and delta, but only 59-62% to beta and gamma, compared to 96-97% of younger vaccinees and 68-76% of infected individuals. Overall, the HAT provides a surrogate marker for neutralising antibodies, could be used as a simple inexpensive, rapid test, rapidly adaptable to emerging VOC for large-scale evaluation of potentially diminishing vaccine effectiveness.

13.
EuropePMC; 2020.
Preprint in English | EuropePMC | ID: ppcovidwho-293860

ABSTRACT

There are as yet no licenced therapeutics for the COVID-19 pandemic. The causal coronavirus (SARS-CoV-2) binds host cells via a trimeric Spike whose receptor binding domain (RBD) recognizes angiotensin-converting enzyme 2 (ACE2), initiating conformational changes that drive membrane fusion. We find that monoclonal antibody CR3022 binds the RBD tightly, neutralising SARS-CoV-2 and report the crystal structure at 2.4 A of the Fab/RBD complex. Some crystals are suitable for screening for entry-blocking inhibitors. The highly conserved, structure-stabilising, CR3022 epitope is inaccessible in the prefusion Spike, suggesting that CR3022 binding would facilitate conversion to the fusion-incompetent post-fusion state. Cryo-EM analysis confirms that incubation of Spike with CR3022 Fab leads to destruction of the prefusion trimer. Presentation of this cryptic epitope in an RBD-based vaccine might advantageously focus immune responses. Binders at this epitope may be useful therapeutically, possibly in synergy with an antibody blocking receptor attachment.<br><br>Funding: This work was supported by a grant from the CAMS-Oxford Institute to D.I.S. E.E.F and J.Ren are supported by the Wellcome Trust (101122/Z/13/Z), Y.Z. by Cancer Research UK (C375/A17721) and D.I.S. and E.E.F. by the UK Medical Research Council (MR/N00065X/1). J.H. is supported by a grant from the EPA Cephalosporin Fund. PPUK is funded by the Rosalind Franklin Institute EPSRC Grant no. EP/S025243/1. The National Institute for Health Research Biomedical Research Centre Funding Scheme supports G.R.S. together with the Chinese Academy of Medical Sciences (CAMS) Innovation Fund for Medical Science (CIFMS), China (grant number: 2018-I2M-2-002), which also supports D.I.S. G.R.S. is also supported as a Wellcome Trust Senior Investigator (grant 095541/A/11/Z). T.M. is supported by Cancer Research UK grants C20724/A14414 and C20724/A26752 to Christian Siebold. This is a contribution from the UK Instruct-ERIC Centre. The Wellcome Centre for Human Genetics is supported by the Wellcome Trust (grant 090532/Z/09/Z). Virus used for the neutralisation assays was a gift from Julian Druce, Doherty Centre, Melbourne, Australia. <br><br>Conflict of Interest: The authors declare no competing interests.

14.
Front Public Health ; 9: 724398, 2021.
Article in English | MEDLINE | ID: covidwho-1555557

ABSTRACT

Background: As the Municipality Council area in Colombo (CMC) experienced the highest number of cases until the end of January 2021, in Sri Lanka, we carried out a serosurvey prior to initiation of the vaccination program to understand the extent of the SARS-CoV-2 outbreak. Methods: SARS-CoV-2 seropositivity was determined in 2,547 individuals between the ages of 10-86 years, by the Wantai total antibody ELISA. We also compared seroprevalence using the haemagglutination test (HAT) to evaluate its usefulness in carrying out serosurveys. Results: The overall seropositivity rate was 24.46%, while seropositivity by HAT was 18.90%. Although The SARS-CoV-2 infection detection rates by PCR were highest in the population between the ages of 20-60 years of age, there was no statistically significant difference in the seropositivity rates in different age groups. For instance, although the seropositivity rate was highest in the 10-20 age group (34.03%), the PCR positivity rate was 9.80%. Differences in the PCR positivity rates and seropositivity rates were also seen in 60-70-year-olds (8.90 vs. 30.4%) and in individuals >70 years (4.10 vs. 1.20%). The seropositivity rate of the females was 29.70% (290/976), which was significantly higher (p < 0.002) than in males 21.2% (333/1,571). Conclusions: A high seroprevalence rate (24.5%) was seen in all age groups in the CMC suggesting that a high level of transmission was seen during this time. The higher PCR positivity rates between the ages of 20-60 are likely to be due to increased testing carried out in the working population. Therefore, the PCR positivity rates, appear to underestimate the true extent of the outbreak and the age groups which were infected.


Subject(s)
COVID-19 , Adolescent , Adult , Aged , Aged, 80 and over , Child , Enzyme-Linked Immunosorbent Assay , Female , Humans , Male , Middle Aged , SARS-CoV-2 , Seroepidemiologic Studies , Sri Lanka/epidemiology , Young Adult
15.
Theranostics ; 12(1): 1-17, 2022.
Article in English | MEDLINE | ID: covidwho-1512993

ABSTRACT

Background: Administration of potent anti-receptor-binding domain (RBD) monoclonal antibodies has been shown to curtail viral shedding and reduce hospitalization in patients with SARS-CoV-2 infection. However, the structure-function analysis of potent human anti-RBD monoclonal antibodies and its links to the formulation of antibody cocktails remains largely elusive. Methods: Previously, we isolated a panel of neutralizing anti-RBD monoclonal antibodies from convalescent patients and showed their neutralization efficacy in vitro. Here, we elucidate the mechanism of action of antibodies and dissect antibodies at the epitope level, which leads to a formation of a potent antibody cocktail. Results: We found that representative antibodies which target non-overlapping epitopes are effective against wild type virus and recently emerging variants of concern, whilst being encoded by antibody genes with few somatic mutations. Neutralization is associated with the inhibition of binding of viral RBD to ACE2 and possibly of the subsequent fusion process. Structural analysis of representative antibodies, by cryo-electron microscopy and crystallography, reveals that they have some unique aspects that are of potential value while sharing some features in common with previously reported neutralizing monoclonal antibodies. For instance, one has a common VH 3-53 public variable region yet is unusually resilient to mutation at residue 501 of the RBD. We evaluate the in vivo efficacy of an antibody cocktail consisting of two potent non-competing anti-RBD antibodies in a Syrian hamster model. We demonstrate that the cocktail prevents weight loss, reduces lung viral load and attenuates pulmonary inflammation in hamsters in both prophylactic and therapeutic settings. Although neutralization of one of these antibodies is abrogated by the mutations of variant B.1.351, it is also possible to produce a bi-valent cocktail of antibodies both of which are resilient to variants B.1.1.7, B.1.351 and B.1.617.2. Conclusions: These findings support the up-to-date and rational design of an anti-RBD antibody cocktail as a therapeutic candidate against COVID-19.


Subject(s)
Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/pharmacology , COVID-19/drug therapy , SARS-CoV-2/metabolism , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Animals , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/chemistry , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/pharmacology , Binding Sites , Binding, Competitive , COVID-19/virology , Cricetinae , Cryoelectron Microscopy , Crystallography, X-Ray , Dogs , Epitopes , Female , Humans , Madin Darby Canine Kidney Cells , Neutralization Tests , Protein Domains , SARS-CoV-2/genetics , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism
16.
J Immunol ; 207(11): 2681-2687, 2021 12 01.
Article in English | MEDLINE | ID: covidwho-1506155

ABSTRACT

Due to limited access to vaccines, many countries have only administered a single dose of the AZD1222, whereas the dosage intervals have increased ≥4 wk. We sought to investigate the immunogenicity of a single dose of vaccine at ≥16 wk postimmunization. Severe acute respiratory syndrome coronavirus 2-specific Abs in 553 individuals and Abs to the receptor-binding domain of the Wuhan virus (wild-type) and the variants of concern, angiotensin-converting enzyme 2 receptor blocking Abs ex vivo and cultured IFN-γ T cell (Homo sapiens) responses and B cell (H. sapiens) ELISPOT responses, were investigated in a subcohort. The seropositivity rates in those >70 y of age (93.7%) was not significantly different compared with other age groups (97.7-98.2; Pearson χ2 = 7.8; p = 0.05). The Ab titers (Ab index) significantly declined (p < 0.0001) with increase in age. A total of 18 of 69 (26.1%) of individuals did not have angiotensin-converting enzyme 2 receptor-blocking Abs, whereas responses to the receptor-binding domain of wild-type (p = 0.03), B.1.1.7 (p = 0.04), and B.1.617.2 (p = 0.02) were significantly lower in those who were >60 y. Ex vivo IFN-γ T cell ELISPOT responses were seen in 10 of 66 (15.1%), whereas only a few expressed CD107a. However, >85% had a high frequency of cultured IFN-γ T cell ELISPOT responses and B cell ELISPOTs. Virus-specific Abs were maintained at ≥16 wk after receiving a single dose of AZD1222, although levels were lower to variants of concern, especially in older individuals. A single dose induced a high frequency of memory T and B cell responses.


Subject(s)
COVID-19 Vaccines/pharmacology , COVID-19/drug therapy , SARS-CoV-2/drug effects , Administration, Oral , Adult , Aged , Aged, 80 and over , B-Lymphocytes/drug effects , B-Lymphocytes/immunology , COVID-19/immunology , COVID-19 Vaccines/administration & dosage , Female , Humans , Male , Middle Aged , SARS-CoV-2/immunology , Young Adult
19.
Nat Commun ; 12(1): 5061, 2021 08 17.
Article in English | MEDLINE | ID: covidwho-1361634

ABSTRACT

The extent to which immune responses to natural infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and immunization with vaccines protect against variants of concern (VOC) is of increasing importance. Accordingly, here we analyse antibodies and T cells of a recently vaccinated, UK cohort, alongside those recovering from natural infection in early 2020. We show that neutralization of the VOC compared to a reference isolate of the original circulating lineage, B, is reduced: more profoundly against B.1.351 than for B.1.1.7, and in responses to infection or a single dose of vaccine than to a second dose of vaccine. Importantly, high magnitude T cell responses are generated after two vaccine doses, with the majority of the T cell response directed against epitopes that are conserved between the prototype isolate B and the VOC. Vaccination is required to generate high potency immune responses to protect against these and other emergent variants.


Subject(s)
COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/immunology , COVID-19/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Angiotensin-Converting Enzyme 2/immunology , Animals , Antibodies, Monoclonal/blood , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/isolation & purification , Antibodies, Neutralizing/metabolism , Antibodies, Viral/blood , Antibodies, Viral/immunology , Carrier Proteins , Epitopes , Humans , Immunity , SARS-CoV-2/drug effects , T-Lymphocytes/immunology
20.
EMBO Rep ; 22(8): e52447, 2021 08 04.
Article in English | MEDLINE | ID: covidwho-1278776

ABSTRACT

Cyclic GMP-AMP (cGAMP) is an immunostimulatory molecule produced by cGAS that activates STING. cGAMP is an adjuvant when administered alongside antigens. cGAMP is also incorporated into enveloped virus particles during budding. Here, we investigate whether inclusion of cGAMP within viral vaccine vectors enhances their immunogenicity. We immunise mice with virus-like particles (VLPs) containing HIV-1 Gag and the vesicular stomatitis virus envelope glycoprotein G (VSV-G). cGAMP loading of VLPs augments CD4 and CD8 T-cell responses. It also increases VLP- and VSV-G-specific antibody titres in a STING-dependent manner and enhances virus neutralisation, accompanied by increased numbers of T follicular helper cells. Vaccination with cGAMP-loaded VLPs containing haemagglutinin induces high titres of influenza A virus neutralising antibodies and confers protection upon virus challenge. This requires cGAMP inclusion within VLPs and is achieved at markedly reduced cGAMP doses. Similarly, cGAMP loading of VLPs containing the SARS-CoV-2 Spike protein enhances Spike-specific antibody titres. cGAMP-loaded VLPs are thus an attractive platform for vaccination.


Subject(s)
COVID-19 , Influenza Vaccines , Vaccines, Virus-Like Particle , Animals , Humans , Mice , Nucleotides, Cyclic , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Vaccines, Virus-Like Particle/genetics
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