Biology subjects

Durocher, Y.

Publications and source records attributed to Durocher, Y..

8 recordsLinked to original sources

bioRxiv2025

Durability of DNA-LNP and mRNA-LNP Vaccine-Induced Immunity Against SARS-CoV-2 XBB.1.5

mRNA-lipid nanoparticle (LNP) vaccines induce robust adaptive immune responses and have proven highly effective against SARS-CoV-2. However, their long-term effectiveness is limited by waning humoral responses, which decline substantially within the first six months post-boost vaccination. DNA-LNPs are being investigated as an alternative vaccine platform, offering prolonged antigen expression and robust immunity. Here, we present the first comparison of SARS-CoV-2 DNA- and mRNA-LNP vaccines in a long-term in vivo challenge model. Both nucleic acid platforms induced strong neutralizing antibody responses and conferred equivalent protection in Syrian hamsters challenged three weeks post-boost. Notably, DNA-LNP vaccination maintained high binding and neutralizing antibody titers six months post-boost, whereas mRNA-LNPs exhibited a marked decline. Correspondingly, while DNA-LNPs completely protected from weight loss, viral replication, and lung pathology at this late timepoint, mRNA-LNP vaccination conferred minimal protection. These findings demonstrate that DNA-LNPs can sustain durable immunity, highlighting their potential as a next-generation vaccine platform that could reduce the need for frequent boosters.

immunology↗

bioRxiv2023

GotGlycans: Role of N343 Glycosylation on the SARS-CoV-2 S RBD Structure and Co-Receptor Binding Across Variants of Concern

Glycosylation of the SARS-CoV-2 spike (S) protein represents a key target for viral evolution because it affects both viral evasion and fitness. Successful variations in the glycan shield are difficult to achieve though, as protein glycosylation is also critical to folding and to structural stability. Within this framework, the identification of glycosylation sites that are structurally dispensable can provide insight into the evolutionary mechanisms of the shield and inform immune surveillance. In this work we show through over 45 s of cumulative sampling from conventional and enhanced molecular dynamics (MD) simulations, how the structure of the immunodominant S receptor binding domain (RBD) is regulated by N-glycosylation at N343 and how this glycans structural role changes from WHu-1, alpha (B.1.1.7), and beta (B.1.351), to the delta (B.1.617.2) and omicron (BA.1 and BA.2.86) variants. More specifically, we find that the amphipathic nature of the N-glycan is instrumental to preserve the structural integrity of the RBD hydrophobic core and that loss of glycosylation at N343 triggers a specific and consistent conformational change. We show how this change allosterically regulates the conformation of the receptor binding motif (RBM) in the WHu-1, alpha and beta RBDs, but not in the delta and omicron variants, due to mutations that reinforce the RBD architecture. In support of these findings, we show that the binding of the RBD to monosialylated ganglioside co-receptors is highly dependent on N343 glycosylation in the WHu-1, but not in the delta RBD, and that affinity changes significantly across VoCs. Ultimately, the molecular and functional insight we provide in this work reinforces our understanding of the role of glycosylation in protein structure and function and it also allows us to identify the structural constraints within which the glycosylation site at N343 can become a hotspot for mutations in the SARS-CoV-2 S glycan shield.

biophysics↗

bioRxiv2023

Heterologous booster with a novel formulation containing glycosylated trimeric S protein is effective againstOmicron

In this study, we evaluated the efficacy of a heterologous three-dose vaccination schedule against the Omicron BA.1 SARS-CoV-2 variant infection using a mouse intranasal challenge model. The vaccination schedules tested in this study consisted of a primary series of 2 doses covered by two commercial vaccines: an mRNA-based vaccine (mRNA1273) or a non-replicative vector-based vaccine (AZD1222/ChAdOx1, hereafter referred to as AZD1222). These were followed by a heterologous booster dose using one of the two vaccine candidates previously designed by us: one containing the glycosylated and trimeric spike protein (S) from the ancestral virus (SW-Vac 2g), and the other from the Delta variant of SARS-CoV-2 (SD-Vac 2g), both formulated with Alhydrogel as an adjuvant. For comparison purposes, homologous three-dose schedules of the commercial vaccines were used. The mRNA-based vaccine, whether used in heterologous or homologous schedules, demonstrated the best performance, significantly increasing both humoral and cellular immune responses. In contrast, for the schedules that included the AZD1222 vaccine as the primary series, the heterologous schemes showed superior immunological outcomes compared to the homologous 3-dose AZD1222 regimen. For these schemes no differences were observed in the immune response obtained when SW-Vac 2g or SD-Vac 2g were used as a booster dose. Neutralizing antibody levels against Omicron BA.1 were low, especially for the schedules using AZD1222. However, a robust Th1 profile, known to be crucial for protection, was observed, particularly for the heterologous schemes that included AZD1222. All the tested schedules were capable of inducing populations of CD4 T effector, memory, and follicular helper T lymphocytes. It is important to highlight that all the evaluated schedules demonstrated a satisfactory safety profile and induced multiple immunological markers of protection. Although the levels of these markers were different among the tested schedules, they appear to complement each other in conferring protection against intranasal challenge with Omicron BA.1 in K18-hACE2 mice. In summary, the results highlight the potential of using the S protein (either ancestral Wuhan or Delta variant)-based vaccine formulation as heterologous boosters in the management of COVID-19, particularly for certain commercial vaccines currently in use.

immunology↗

bioRxiv2023

SARS-CoV-2 spike antigen-specific B cell and antibody responses in pre-vaccination period COVID-19 convalescent males and females with or without post-covid condition

BackgroundFollowing SARS-CoV-2 infection a significant proportion of convalescent individuals develop the post-COVID condition (PCC) that is characterized by wide spectrum of symptoms encompassing various organs. Even though the underlying pathophysiology of PCC is not known, detection of viral transcripts and antigens in tissues other than lungs raise the possibility that PCC may be a consequence of aberrant immune response to the viral antigens. To test this hypothesis, we evaluated B cell and antibody responses to the SARS-CoV-2 antigens in PCC patients who experienced mild COVID-19 disease during the pre-vaccination period of COVID-19 pandemic. MethodsThe study subjects included unvaccinated male and female subjects who developed PCC or not (No-PCC) after clearing RT-PCR confirmed mild COVID-19 infection. SARS-CoV-2 D614G and omicron RBD specific B cell subsets in peripheral circulation were assessed by flow cytometry. IgG, IgG3 and IgA antibody titers toward RBD, spike and nucleocapsid antigens in the plasma were evaluated by ELISA. ResultsThe frequency of the B cells specific to D614G-RBD were comparable in convalescent groups with and without PCC in both males and females. Notably, in females with PCC, the anti-D614G RBD specific double negative (IgD-CD27-) B cells showed significant correlation with the number of symptoms at acute of infection. Anti-spike antibody responses were also higher at 3 months post-infection in females who developed PCC, but not in the male PCC group. On the other hand, the male PCC group also showed consistently high anti-RBD IgG responses compared to all other groups. ConclusionsThe antibody responses to the spike protein, but not the RBD-specific B cell responses diverge between convalescent males and females, and those who develop PCC or not. Our findings suggest that sex-related factors may also be involved in the development of PCC via modulating antibody responses to the SARS-CoV-2 antigens. Short SummaryPost-COVID Condition (PCC) is lingering illness that afflicts a significant proportion of COVID-19 patients from three months after clearing SARS-CoV-2 infection. Therapy for PCC is only palliative and the underlying disease mechanisms are unclear. The wide spectrum of PCC symptoms that can affect different organs and the detection of viral components in tissues distant from lungs raise the possibility that PCC may be associated with aberrant immune response due to presence of viral antigens. Therefore, we studied B cell and antibody responses to the spike and nucleoprotein antigens in PCC patients who cleared mild SARS-CoV-2 infection during the pre-vaccination COVID-19 pandemic period. We observed divergent patterns of immune reactivity to the spike protein in PCC males and females at different times post-infection, suggesting that the immune responses in PCC may also be influenced by sex-related factors.

immunology↗

bioRxiv2023

BCG administration promotes the long-term protection afforded by a single-dose intranasal adenovirus-based SARS-CoV-2 vaccine

Despite medical interventions and several approved vaccines, the COVID-19 pandemic is continuing into its third year. Recent publications have explored single-dose intranasal (i.n.) adenovirus-based vaccines as an effective strategy for curbing SARS-CoV-2 in naive animal models. However, the effects of prior immunizations and infections have yet to be considered within these models. Here, we investigate the immunomodulatory effects of Mycobacterium bovis BCG pre-immunization on a subsequent S-protein expressing i.n. Ad vaccination, termed Ad(Spike). We found that Ad(Spike) alone conferred long-term protection from severe SARS-CoV-2 pathology within a mouse model, yet it was unable to limit initial infection 6 months post-vaccination. While i.n. Ad(Spike) retains some protective effect after 6 months, a single administration of BCG-Danish prior to Ad(Spike) vaccination potentiates its ability to control viral replication of the B.1.351 SARS-CoV-2 variant within the respiratory tract. Though BCG-Danish had no effect on the ability of Ad(Spike) to generate and maintain humoral immunity, it promoted the generation of cytotoxic and Th1 responses over suppressive FoxP3+ TREG cells in the lungs of infected mice. These data demonstrate a novel vaccination strategy that may prove useful in limiting future viral pandemics by potentiating the long-term efficacy of next generation mucosal vaccines within the context of the safe and widely distributed BCG vaccine. One sentence summaryBCG enhances anti-SARS-CoV-2 immunity and protection afforded by a novel adenovirus-vectored vaccine.

immunology↗

bioRxiv2022

Intranasal Immunization with a Proteosome-Adjuvanted SARS-CoV2 Spike Protein-Based Vaccine is Immunogenic and Efficacious in Mice & Hamsters

With the persistence of the SARS-CoV-2 pandemic and the emergence of novel variants, the development of novel vaccine formulations with enhanced immunogenicity profiles could help reduce disease burden in the future. Intranasally delivered vaccines offer a new modality to prevent SARS-CoV-2 infections through the induction of protective immune responses at the mucosal surface where viral entry occurs. Herein, we evaluated a novel protein subunit vaccine formulation containing a resistin-trimerized prefusion Spike antigen (SmT1v3) and a proteosome-based mucosal adjuvant (BDX301) formulated to enable intranasal immunization. In mice, the formulation induced robust antigen-specific IgG and IgA titers, in the blood and lungs, respectively. In addition, the formulations were highly efficacious in a hamster challenge model, reducing viral load and body weight loss. In both models, the serum antibodies had strong neutralizing activity, preventing the cellular binding of the viral Spike protein based on the ancestral reference strain, the Beta (B.1.351) and Delta (B.1.617.2) variants of concern. As such, this intranasal vaccine formulation warrants further development as a novel SARS-CoV-2 vaccine.

immunology↗

bioRxiv2021

Arsenal of Nanobodies for Broad-Spectrum Countermeasures against Current and Future SARS-CoV-2 Variants of Concerns

Nanobodies offer several potential advantages over mAbs for the control of SARS-CoV-2. Their ability to access cryptic epitopes conserved across SARS-CoV-2 variants of concern (VoCs) and feasibility to engineer modular, multimeric designs, make these antibody fragments ideal candidates for developing broad-spectrum therapeutics against current and continually emerging SARS-CoV-2 VoCs. Here we describe a diverse collection of 37 anti-SARS-CoV-2 spike glycoprotein nanobodies extensively characterized as both monovalent and IgG Fc-fused bivalent modalities. The panel of nanobodies were shown to have high intrinsic affinity; high thermal, thermodynamic and aerosolization stability; broad subunit/domain specificity and cross-reactivity across many VoCs; wide-ranging epitopic and mechanistic diversity; high and broad in vitro neutralization potencies; and high neutralization efficacies in hamster models of SARS-CoV-2 infection, reducing viral burden by up to six orders of magnitude to below detectable levels. In vivo protection was demonstrated with anti-RBD and previously unreported anti-NTD and anti-S2 nanobodies. This collection of nanobodies provides a therapeutic toolbox from which various cocktails or multi-paratopic formats could be built to tackle current and future SARS-CoV-2 variants and SARS-related viruses. Furthermore, the high aerosol-ability of nanobodies provides the option for effective needle-free delivery through inhalation.

bioengineering↗

bioRxiv2020

Rapid, high-yield production of full-length SARS-CoV-2 spike ectodomain by transient gene expression in CHO cells

Recombinant forms of the spike protein of SARS-CoV-2 and related viruses have proven difficult to produce with good yields in mammalian cells. Given the panoply of potential COVID-19 diagnostic tools and therapeutic candidates that require purified spike protein and its importance for ongoing SARS-CoV-2 research, we have explored new approaches for spike production and purification. Three transient gene expression methods based on PEI-mediated transfection of CHO or HEK293 cells in suspension culture in chemically-defined media were compared for rapid production of full-length SARS-CoV-2 ectodomain. A high-cell-density protocol using DXB11-derived CHOBRI/rcTA cells gave substantially better yields than the other methods. Different forms of the spike were expressed, including the wild-type SARS-CoV-2 sequence and a mutated/stabilized form (to favor expression of the full-length spike in prefusion conformation), with and without fusion to putative trimerization domains. An efficient two-step affinity purification method was also developed. Ultimately, we have been able to produce highly homogenous preparations of full-length spike, both monomeric and trimeric, with yields of 100-150 mg/L. The speed and productivity of this method support further development of CHO-based approaches for recombinant spike protein manufacturing.

bioengineering↗