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  1. Article ; Online: Injecting drug use and hepatitis C virus infection independently increase biomarkers of inflammatory disease risk which are incompletely restored by curative direct-acting antiviral therapy.

    Hearps, Anna C / Vootukuru, Nikil / Ebrahimnezhaddarzi, Salimeh / Harney, Brendan L / Boo, Irene / Nguyen, Long / Pavlyshyn, Damian / Dietze, Paul M / Drummer, Heidi E / Thompson, Alexander J / Jaworowski, Anthony / Hellard, Margaret E / Sacks-Davis, Rachel / Doyle, Joseph S

    Frontiers in immunology

    2024  Volume 15, Page(s) 1352440

    Abstract: Background: Hepatitis C virus (HCV) infections are more prevalent in people who inject drugs (PWID) who often experience additional health risks. HCV induces inflammation and immune alterations that contribute to hepatic and non-hepatic morbidities. It ... ...

    Abstract Background: Hepatitis C virus (HCV) infections are more prevalent in people who inject drugs (PWID) who often experience additional health risks. HCV induces inflammation and immune alterations that contribute to hepatic and non-hepatic morbidities. It remains unclear whether curative direct acting antiviral (DAA) therapy completely reverses immune alterations in PWID.
    Methods: Plasma biomarkers of immune activation associated with chronic disease risk were measured in HCV-seronegative (n=24) and HCV RNA+ (n=32) PWID at baseline and longitudinally after DAA therapy. Adjusted generalised estimating equations were used to assess longitudinal changes in biomarker levels. Comparisons between community controls (n=29) and HCV-seronegative PWID were made using adjusted multiple regression modelling.
    Results: HCV-seronegative PWID exhibited significantly increased levels of inflammatory biomarkers including soluble (s) TNF-RII, IL-6, sCD14 and sCD163 and the diabetes index HbA1c as compared to community controls. CXCL10, sTNF-RII, vascular cell adhesion molecule-1 and lipopolysaccharide binding protein (LBP) were additionally elevated in PWID with viremic HCV infection as compared to HCV- PWID. Whilst curative DAA therapy reversed some biomarkers, others including LBP and sTNF-RII remained elevated 48 weeks after HCV cure.
    Conclusion: Elevated levels of inflammatory and chronic disease biomarkers in PWID suggest an increased risk of chronic morbidities such as diabetes and cardiovascular disease. HCV infection in PWID poses an additional disease burden, amplified by the incomplete reversal of immune dysfunction following DAA therapy. These findings highlight the need for heightened clinical surveillance of PWID for chronic inflammatory diseases, particularly those with a history of HCV infection.
    MeSH term(s) Humans ; Hepacivirus ; Antiviral Agents/therapeutic use ; Substance Abuse, Intravenous/complications ; Substance Abuse, Intravenous/drug therapy ; Substance Abuse, Intravenous/epidemiology ; Hepatitis C, Chronic/complications ; Hepatitis C, Chronic/drug therapy ; Hepatitis C/complications ; Hepatitis C/drug therapy ; Biomarkers ; Diabetes Mellitus/drug therapy
    Chemical Substances Antiviral Agents ; Biomarkers
    Language English
    Publishing date 2024-02-14
    Publishing country Switzerland
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2606827-8
    ISSN 1664-3224 ; 1664-3224
    ISSN (online) 1664-3224
    ISSN 1664-3224
    DOI 10.3389/fimmu.2024.1352440
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Enhanced stability of the SARS CoV-2 spike glycoprotein following modification of an alanine cavity in the protein core.

    Poumbourios, Pantelis / Langer, Christine / Boo, Irene / Zakir, Tasnim / Center, Rob J / Akerman, Anouschka / Milogiannakis, Vanessa / Aggarwal, Anupriya / Johnstone, Bronte A / Ha, Jungmin / Coulibaly, Fasséli / Turville, Stuart G / Drummer, Heidi E

    PLoS pathogens

    2023  Volume 19, Issue 5, Page(s) e1010981

    Abstract: The spike (S) glycoprotein of SARS CoV-2 is the target of neutralizing antibodies (NAbs) that are crucial for vaccine effectiveness. The S1 subunit binds ACE2 while the S2 subunit mediates virus-cell membrane fusion. S2 is a class I fusion glycoprotein ... ...

    Abstract The spike (S) glycoprotein of SARS CoV-2 is the target of neutralizing antibodies (NAbs) that are crucial for vaccine effectiveness. The S1 subunit binds ACE2 while the S2 subunit mediates virus-cell membrane fusion. S2 is a class I fusion glycoprotein subunit and contains a central coiled coil that acts as a scaffold for the conformational changes associated with fusion function. The coiled coil of S2 is unusual in that the 3-4 repeat of inward-facing positions are mostly occupied by polar residues that mediate few inter-helical contacts in the prefusion trimer. We examined how insertion of bulkier hydrophobic residues (Val, Leu, Ile, Phe) to fill a cavity next to Ala1016 and Ala1020 in the 3-4 repeat affects the stability and antigenicity of S trimers. Substitution of Ala1016 with bulkier hydrophobic residues in the context of a prefusion-stabilized S trimer, S2P-FHA, was associated with increased thermal stability. S glycoprotein membrane fusion function was retained with Ala1016/Ala1020 cavity-filling mutations associated with improved recombinant S2P-FHA thermostability, however 2 mutants, A1016L and A1016V/A1020I, lacked ability to mediate entry of S-HIV-1 pseudoparticles into 293-ACE2 cells. When assessed as immunogens, two thermostable S2P-FHA mutants derived from the ancestral isolate, A1016L (16L) and A1016V/A1020I (VI) elicited neutralizing antibody with 50%-inhibitory dilutions (ID50s) in the range 2,700-5,110 for ancestral and Delta-derived viruses, and 210-1,744 for Omicron BA.1. The antigens elicited antibody specificities directed to the receptor-binding domain (RBD), N-terminal domain (NTD), fusion peptide and stem region of S2. The VI mutation enabled the production of intrinsically stable Omicron BA.1 and Omicron BA.4/5 S2P-FHA-like ectodomain oligomers in the absence of an external trimerization motif (T4 foldon), thus representing an alternative approach for stabilizing oligomeric S glycoprotein vaccines.
    MeSH term(s) Humans ; Spike Glycoprotein, Coronavirus ; Severe Acute Respiratory Syndrome ; Angiotensin-Converting Enzyme 2 ; COVID-19 ; Antibodies, Neutralizing
    Chemical Substances spike protein, SARS-CoV-2 ; Spike Glycoprotein, Coronavirus ; Angiotensin-Converting Enzyme 2 (EC 3.4.17.23) ; Antibodies, Neutralizing
    Language English
    Publishing date 2023-05-18
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2205412-1
    ISSN 1553-7374 ; 1553-7374
    ISSN (online) 1553-7374
    ISSN 1553-7374
    DOI 10.1371/journal.ppat.1010981
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  3. Article ; Online: Enhancing the antigenicity and immunogenicity of monomeric forms of hepatitis C virus E2 for use as a preventive vaccine.

    Center, Rob J / Boo, Irene / Phu, Lilian / McGregor, Joey / Poumbourios, Pantelis / Drummer, Heidi E

    The Journal of biological chemistry

    2020  Volume 295, Issue 21, Page(s) 7179–7192

    Abstract: The E2 glycoprotein of hepatitis C virus (HCV) is the major target of broadly neutralizing antibodies (bNAbs) that are critical for the efficacy of a prophylactic HCV vaccine. We previously showed that a cell culture-derived, disulfide-linked high- ... ...

    Abstract The E2 glycoprotein of hepatitis C virus (HCV) is the major target of broadly neutralizing antibodies (bNAbs) that are critical for the efficacy of a prophylactic HCV vaccine. We previously showed that a cell culture-derived, disulfide-linked high-molecular-weight (HMW) form of the E2 receptor-binding domain lacking three variable regions, Δ123-HMW, elicits broad neutralizing activity against the seven major genotypes of HCV. A limitation to the use of this antigen is that it is produced only at low yields and does not have a homogeneous composition. Here, we employed a sequential reduction and oxidation strategy to efficiently refold two high-yielding monomeric E2 species, D123 and a disulfide-minimized version (D123A7), into disulfide-linked HMW-like species (Δ123r and Δ123A7r). These proteins exhibited normal reactivity to bNAbs with continuous epitopes on the neutralizing face of E2, but reduced reactivity to conformation-dependent bNAbs and nonneutralizing antibodies (non-NAbs) compared with the corresponding monomeric species. Δ123r and Δ123A7r recapitulated the immunogenic properties of cell culture-derived D123-HMW in guinea pigs. The refolded antigens elicited antibodies that neutralized homologous and heterologous HCV genotypes, blocked the interaction between E2 and its cellular receptor CD81, and targeted the AS412, AS434, and AR3 domains. Of note, antibodies directed to epitopes overlapping with those of non-NAbs were absent. The approach to E2 antigen engineering outlined here provides an avenue for the development of preventive HCV vaccine candidates that induce bNAbs at higher yield and lower cost.
    MeSH term(s) Amino Acid Substitution ; Animals ; Antibodies, Neutralizing/immunology ; Glycoproteins/genetics ; Glycoproteins/immunology ; Guinea Pigs ; Hepacivirus/genetics ; Hepacivirus/immunology ; Hepatitis Antibodies/immunology ; Hepatitis Antigens/genetics ; Hepatitis Antigens/immunology ; Humans ; Immunogenicity, Vaccine ; Mutation, Missense ; Viral Hepatitis Vaccines/genetics ; Viral Hepatitis Vaccines/immunology ; Viral Proteins/genetics ; Viral Proteins/immunology
    Chemical Substances Antibodies, Neutralizing ; Glycoproteins ; Hepatitis Antibodies ; Hepatitis Antigens ; Viral Hepatitis Vaccines ; Viral Proteins
    Language English
    Publishing date 2020-04-16
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1074/jbc.RA120.013015
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: COVID-19 Adenoviral Vector Vaccination Elicits a Robust Memory B Cell Response with the Capacity to Recognize Omicron BA.2 and BA.5 Variants.

    Fryer, Holly A / Hartley, Gemma E / Edwards, Emily S J / Varese, Nirupama / Boo, Irene / Bornheimer, Scott J / Hogarth, P Mark / Drummer, Heidi E / O'Hehir, Robyn E / van Zelm, Menno C

    Journal of clinical immunology

    2023  Volume 43, Issue 7, Page(s) 1506–1518

    Abstract: Following the COVID-19 pandemic, novel vaccines have successfully reduced severe disease and death. Despite eliciting lower antibody responses, adenoviral vector vaccines are nearly as effective as mRNA vaccines. Therefore, protection against severe ... ...

    Abstract Following the COVID-19 pandemic, novel vaccines have successfully reduced severe disease and death. Despite eliciting lower antibody responses, adenoviral vector vaccines are nearly as effective as mRNA vaccines. Therefore, protection against severe disease may be mediated by immune memory cells. We here evaluated plasma antibody and memory B cells (Bmem) targeting the SARS-CoV-2 Spike receptor-binding domain (RBD) elicited by the adenoviral vector vaccine ChAdOx1 (AstraZeneca), their capacity to bind Omicron subvariants, and compared this to the response to mRNA BNT162b2 (Pfizer-BioNTech) vaccination. Whole blood was sampled from 31 healthy adults pre-vaccination and 4 weeks after dose one and dose two of ChAdOx1. Neutralizing antibodies (NAb) against SARS-CoV-2 were quantified at each time point. Recombinant RBDs of the Wuhan-Hu-1 (WH1), Delta, BA.2, and BA.5 variants were produced for ELISA-based quantification of plasma IgG and incorporated separately into fluorescent tetramers for flow cytometric identification of RBD-specific Bmem. NAb and RBD-specific IgG levels were over eight times lower following ChAdOx1 vaccination than BNT162b2. In ChAdOx1-vaccinated individuals, median plasma IgG recognition of BA.2 and BA.5 as a proportion of WH1-specific IgG was 26% and 17%, respectively. All donors generated resting RBD-specific Bmem, which were boosted after the second dose of ChAdOx1 and were similar in number to those produced by BNT162b2. The second dose of ChAdOx1 boosted Bmem that recognized VoC, and 37% and 39% of WH1-specific Bmem recognized BA.2 and BA.5, respectively. These data uncover mechanisms by which ChAdOx1 elicits immune memory to confer effective protection against severe COVID-19.
    MeSH term(s) Adult ; Humans ; BNT162 Vaccine ; Memory B Cells ; Pandemics ; COVID-19/prevention & control ; SARS-CoV-2 ; Vaccination ; Adenoviridae ; Antibodies, Neutralizing ; Immunoglobulin G ; Antibodies, Viral
    Chemical Substances BNT162 Vaccine ; Antibodies, Neutralizing ; Immunoglobulin G ; Antibodies, Viral
    Language English
    Publishing date 2023-06-16
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 779361-3
    ISSN 1573-2592 ; 0271-9142
    ISSN (online) 1573-2592
    ISSN 0271-9142
    DOI 10.1007/s10875-023-01527-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: B cell characteristics define HCV reinfection outcome.

    Underwood, Alexander P / Gupta, Money / Wu, Bing-Ru / Eltahla, Auda A / Boo, Irene / Wang, Jing Jing / Agapiou, David / Abayasingam, Arunasingam / Reynaldi, Arnold / Keoshkerian, Elizabeth / Zhao, Yanran / Brasher, Nicholas / Walker, Melanie R / Bukh, Jens / Maher, Lisa / Gordon, Tom / Davenport, Miles P / Luciani, Fabio / Drummer, Heidi E /
    Lloyd, Andrew R / Bull, Rowena A

    Journal of hepatology

    2024  

    Abstract: Background and aims: In individuals highly exposed to hepatitis C virus (HCV), reinfection is common, suggesting that natural development of sterilising immunity is difficult. In those that are reinfected, some will develop a persistent infection, while ...

    Abstract Background and aims: In individuals highly exposed to hepatitis C virus (HCV), reinfection is common, suggesting that natural development of sterilising immunity is difficult. In those that are reinfected, some will develop a persistent infection, while a small proportion repeatedly clear the virus, suggesting natural protection is possible. The aim of this study was to characterise immune responses associated with rapid natural clearance of HCV reinfection.
    Methods: Broad neutralising antibodies (BnAbs) and Envelope 2 (E2)-specific memory B cell (MBCs) responses were examined longitudinally in 15 subjects with varied reinfection outcomes.
    Results: BnAb responses were associated with MBC recall, but not with reinfection clearance. Strong evidence of antigen imprinting was found, and the B cell receptor repertoire showed a high level of clonality with ongoing somatic hypermutation of many clones over subsequent reinfection events. Single cell transcriptomic analyses showed that cleared reinfections featured an activated transcriptomic profile in HCV-specific B cells that rapidly expanded upon reinfection.
    Conclusions: MBC quality, but not necessarily breadth of nAb responses, is important for protection against antigenically diverse variants, which is encouraging for HCV vaccine development.
    Language English
    Publishing date 2024-04-09
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 605953-3
    ISSN 1600-0641 ; 0168-8278
    ISSN (online) 1600-0641
    ISSN 0168-8278
    DOI 10.1016/j.jhep.2024.04.004
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Serological assays to measure dimeric IgA antibodies in SARS-CoV-2 infections.

    Wei, Zihui / Angrisano, Fiona / Eriksson, Emily M / Mazhari, Ramin / Van, Huy / Zheng, Shuning / Center, Rob J / Boo, Irene / McMahon, James / Lau, Jillian / Kiernan-Walker, Nicholas / Ruybal-Pesántez, Shazia / Mueller, Ivo / Robinson, Leanne J / Anderson, David A / Drummer, Heidi E

    Immunology and cell biology

    2023  Volume 101, Issue 9, Page(s) 857–866

    Abstract: Current serological tests cannot differentiate between total immunoglobulin A (IgA) and dimeric IgA (dIgA) associated with mucosal immunity. Here, we describe two new assays, dIgA-ELISA and dIgA-multiplex bead assay (MBA), that utilize the preferential ... ...

    Abstract Current serological tests cannot differentiate between total immunoglobulin A (IgA) and dimeric IgA (dIgA) associated with mucosal immunity. Here, we describe two new assays, dIgA-ELISA and dIgA-multiplex bead assay (MBA), that utilize the preferential binding of dIgA to a chimeric form of secretory component, allowing the differentiation between dIgA and monomeric IgA. dIgA responses elicited through severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were measured in (i) a longitudinal panel, consisting of 74 samples (n = 20 individuals) from hospitalized cases of coronavirus disease 2019 (COVID-19); (ii) a longitudinal panel, consisting of 96 samples (n = 10 individuals) from individuals with mild COVID-19; (iii) a cross-sectional panel with PCR-confirmed SARS-CoV-2 infection with mild COVID-19 (n = 199) and (iv) pre-COVID-19 samples (n = 200). The dIgA-ELISA and dIgA-MBA demonstrated a specificity for dIgA of 99% and 98.5%, respectively. Analysis of dIgA responses in the longitudinal panels revealed that 70% (ELISA) and 50% (MBA) of patients elicited a dIgA response by day 20 after PCR diagnosis with a SARS-CoV-2 infection. Individuals with mild COVID-19 displayed increased levels of dIgA within the first 3 weeks after diagnosis but responses appeared to be short lived, compared with sustained IgA levels. However, in samples from hospitalized patients with COVID-19 we observed high and sustained levels of dIgA, up to 245 days after PCR diagnosis. Our results suggest that severe COVID-19 infections are associated with sustained levels of plasma dIgA compared with mild cases.
    MeSH term(s) Humans ; COVID-19/diagnosis ; SARS-CoV-2/metabolism ; Cross-Sectional Studies ; Immunoglobulin A ; Antibodies, Viral ; Immunoglobulin M
    Chemical Substances Immunoglobulin A ; Antibodies, Viral ; Immunoglobulin M
    Language English
    Publishing date 2023-08-18
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 284057-1
    ISSN 1440-1711 ; 0818-9641
    ISSN (online) 1440-1711
    ISSN 0818-9641
    DOI 10.1111/imcb.12682
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  7. Article ; Online: Virus-Like Particles Containing the E2 Core Domain of Hepatitis C Virus Generate Broadly Neutralizing Antibodies in Guinea Pigs.

    McGregor, Joey / Hardy, Joshua M / Lay, Chan-Sien / Boo, Irene / Piontek, Michael / Suckow, Manfred / Coulibaly, Fasséli / Poumbourios, Pantelis / Center, Rob J / Drummer, Heidi E

    Journal of virology

    2022  Volume 96, Issue 5, Page(s) e0167521

    Abstract: A vaccine to prevent hepatitis C virus (HCV) infection is urgently needed for use alongside direct-acting antiviral drugs to achieve elimination targets. We have previously shown that a soluble recombinant form of the glycoprotein E2 ectodomain (residues ...

    Abstract A vaccine to prevent hepatitis C virus (HCV) infection is urgently needed for use alongside direct-acting antiviral drugs to achieve elimination targets. We have previously shown that a soluble recombinant form of the glycoprotein E2 ectodomain (residues 384 to 661) that lacks three variable regions (Δ123) is able to elicit a higher titer of broadly neutralizing antibodies (bNAbs) than the parental form (receptor-binding domain [RBD]). In this study, we engineered a viral nanoparticle that displays HCV glycoprotein E2 on a duck hepatitis B virus (DHBV) small surface antigen (S) scaffold. Four variants of E2-S virus-like particles (VLPs) were constructed: Δ123-S, RBD-S, Δ123A7-S, and RBDA7-S; in the last two, 7 cysteines were replaced with alanines. While all four E2-S variant VLPs display E2 as a surface antigen, the Δ123A7-S and RBDA7-S VLPs were the most efficiently secreted from transfected mammalian cells and displayed epitopes recognized by cross-genotype broadly neutralizing monoclonal antibodies (bNMAbs). Both Δ123A7-S and RBDA7-S VLPs were immunogenic in guinea pigs, generating high titers of antibodies reactive to native E2 and able to prevent the interaction between E2 and the cellular receptor CD81. Four out of eight animals immunized with Δ123A7-S elicited neutralizing antibodies (NAbs), with three of those animals generating bNAbs against 7 genotypes. Immune serum generated by animals with NAbs mapped to major neutralization epitopes located at residues 412 to 420 (epitope I) and antigenic region 3. VLPs that display E2 glycoproteins represent a promising vaccine platform for HCV and could be adapted to large-scale manufacturing in yeast systems.
    MeSH term(s) Animals ; Antigens, Surface/immunology ; Broadly Neutralizing Antibodies/immunology ; Epitopes/immunology ; Guinea Pigs ; Hepacivirus/genetics ; Hepacivirus/immunology ; Hepatitis B Surface Antigens/chemistry ; Hepatitis C/immunology ; Hepatitis C Antibodies/immunology ; Humans ; Viral Envelope Proteins/immunology ; Viral Hepatitis Vaccines/immunology
    Chemical Substances Antigens, Surface ; Broadly Neutralizing Antibodies ; Epitopes ; Hepatitis B Surface Antigens ; Hepatitis C Antibodies ; Viral Envelope Proteins ; Viral Hepatitis Vaccines
    Language English
    Publishing date 2022-01-05
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80174-4
    ISSN 1098-5514 ; 0022-538X
    ISSN (online) 1098-5514
    ISSN 0022-538X
    DOI 10.1128/JVI.01675-21
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  8. Article ; Online: The second COVID-19 mRNA vaccine dose enhances the capacity of Spike-specific memory B cells to bind Omicron BA.2.

    Hartley, Gemma E / Edwards, Emily S J / Varese, Nirupama / Boo, Irene / Aui, Pei M / Bornheimer, Scott J / Hogarth, P Mark / Drummer, Heidi E / O'Hehir, Robyn E / van Zelm, Menno C

    Allergy

    2022  Volume 78, Issue 3, Page(s) 855–858

    MeSH term(s) Humans ; COVID-19/prevention & control ; COVID-19 Vaccines ; Memory B Cells ; Antibodies, Neutralizing ; mRNA Vaccines
    Chemical Substances COVID-19 Vaccines ; Antibodies, Neutralizing
    Language English
    Publishing date 2022-12-30
    Publishing country Denmark
    Document type Letter ; Research Support, Non-U.S. Gov't
    ZDB-ID 391933-x
    ISSN 1398-9995 ; 0105-4538
    ISSN (online) 1398-9995
    ISSN 0105-4538
    DOI 10.1111/all.15624
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  9. Article ; Online: COVID-19 adenoviral vector vaccination elicits a robust memory B cell response with the capacity to recognize Omicron BA.2 and BA.5 variants

    Fryer, Holly A. / Hartley, Gemma E. / Edwards, Emily S.J. / Varese, Nirupama / Boo, Irene / Bornheimer, Scott J. / Hogarth, P. Mark / Drummer, Heidi E. / O'Hehir, Robyn E. / van Zelm, Menno C

    bioRxiv

    Abstract: Following the COVID-19 pandemic caused by SARS-CoV-2, novel vaccines have successfully reduced severe disease and death. Despite eliciting lower antibody responses, adenoviral vector vaccines are nearly as effective as mRNA vaccines. Therefore, ... ...

    Abstract Following the COVID-19 pandemic caused by SARS-CoV-2, novel vaccines have successfully reduced severe disease and death. Despite eliciting lower antibody responses, adenoviral vector vaccines are nearly as effective as mRNA vaccines. Therefore, protection against severe disease may be mediated by immune memory cells. We here evaluated plasma antibody and memory B cells (Bmem) targeting the Spike receptor binding domain (RBD) elicited by the adenoviral vector vaccine ChAdOx1 (AstraZeneca), their capacity to bind Omicron subvariants, and compared this to the response elicited by the mRNA vaccine BNT162b2 (Pfizer-BioNTech). Whole blood was sampled from 31 healthy adults pre-vaccination, and four weeks after dose one and dose two of ChAdOx1. Neutralizing antibodies (NAb) against SARS-CoV-2 were quantified at each timepoint. Recombinant RBDs of the Wuhan-Hu-1 (WH1), Delta, BA.2, and BA.5 variants were produced for ELISA-based quantification of plasma IgG and incorporated separately into fluorescent tetramers for flow cytometric identification of RBD-specific Bmem. NAb and RBD-specific IgG levels were over eight times lower following ChAdOx1 vaccination than BNT162b2. In ChAdOx1-vaccinated individuals, median plasma IgG recognition of BA.2 and BA.5 as a proportion of WH1-specific IgG was 26% and 17%, respectively. All donors generated resting RBD-specific Bmem, which were boosted after the second dose of ChAdOx1, and were similar in number to those produced by BNT162b2. The second dose of ChAdOx1 boosted Bmem that recognized VoC, and 37% and 39% of WH1-specific Bmem recognized BA.2 and BA.5, respectively. These data uncover mechanisms by which ChAdOx1 elicits immune memory to confer effective protection against severe COVID-19.
    Keywords covid19
    Language English
    Publishing date 2023-03-01
    Publisher Cold Spring Harbor Laboratory
    Document type Article ; Online
    DOI 10.1101/2023.02.28.530547
    Database COVID19

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  10. Article ; Online: Third dose COVID-19 mRNA vaccine enhances IgG4 isotype switching and recognition of Omicron subvariants by memory B cells after mRNA but not adenovirus priming

    Hartley, Gemma E. / Fryer, Holly A. / Gill, Paul A. / Boo, Irene / Bornheimer, Scott J. / Hogarth, P. Mark / Drummer, Heidi E. / O’Hehir, Robyn E. / Edwards, Emily S.J. / van Zelm, Menno C.

    bioRxiv

    Abstract: Background: Booster vaccinations are recommended to improve protection against severe disease from SARS-CoV-2 infection. With primary vaccinations involving various adenoviral vector and mRNA-based formulations, it remains unclear if these differentially ...

    Abstract Background: Booster vaccinations are recommended to improve protection against severe disease from SARS-CoV-2 infection. With primary vaccinations involving various adenoviral vector and mRNA-based formulations, it remains unclear if these differentially affect the immune response to booster doses. We here examined the effects of homologous (mRNA/mRNA) and heterologous (adenoviral vector/mRNA) vaccination on antibody and memory B cell (Bmem) responses against ancestral and Omicron subvariants. Methods: Healthy adults who received primary BNT162b2 (mRNA) (n=18) or ChAdOx1 (vector) (n=25) vaccination were sampled 1-month and 6-months after their 2nd and 3rd dose (homologous or heterologous) vaccination. Recombinant spike receptor-binding domain (RBD) proteins from ancestral, Omicron BA.2 and BA.5 variants were produced for ELISA-based serology, and tetramerized for immunophenotyping of RBD-specific Bmem. Results: Dose 3 boosters significantly increased ancestral RBD-specific plasma IgG and Bmem in both cohorts. Up to 80% of ancestral RBD-specific Bmem expressed IgG1+. IgG4+ Bmem were detectable after primary mRNA vaccination, and expanded significantly to 5-20% after dose 3, whereas heterologous boosting did not elicit IgG4+ Bmem. Recognition of Omicron BA.2 and BA.5 by ancestral RBD-specific plasma IgG increased from 20% to 60% after the 3rd dose in both cohorts. Reactivity of ancestral RBD-specific Bmem to Omicron BA.2 and BA.5 increased following a homologous booster from 40% to 60%, but not after a heterologous booster. Conclusion: A 3rd mRNA dose generates similarly robust serological and Bmem responses in homologous and heterologous vaccination groups. The expansion of IgG4+ Bmem after mRNA priming might result from the unique vaccine formulation or dosing schedule affecting the Bmem response duration and antibody maturation.
    Keywords covid19
    Language English
    Publishing date 2023-09-19
    Publisher Cold Spring Harbor Laboratory
    Document type Article ; Online
    DOI 10.1101/2023.09.15.557929
    Database COVID19

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