Jul 2026· Journal of Translational Medicine· 0 citations
Medicine
TL;DR
Heterologous boosting with Ad5-nCoV elicited more mature B cells with higher affinity and activated more abundant immune-related pathways compared to the homologous boosting with CoronaVac, which gives insights for elaborating the systemic immune landscape of heterologous-boosting COVID-19 immunization by the novel single B cell sorting platform and scRNA/V(D)J-seq technology.
Abstract
Background
Compared with homologous boosting, heterologous boosting with a different COVID-19 vaccine following priming generates stronger antibody responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as well as variants, particularly for inactivated COVID-19 vaccine(CoronaVac). However, it is still unclear about the potential immune enhancement mechanism underlying heterologous boosting.
Methods
In this study, we isolated spike protein binding-specific monoclonal antibodies at day 180 post a homologous booster with CoronaVac or a heterologous booster with Ad5-nCoV based on two-dose of CoronaVac using the single B cell sorting platform. Subsequently, we verified their neutralization activity to SARS-CoV-2 variants, germline gene sequences and affinity kinetics targeting SARS-CoV-2 NTD/RBD/S1. Additionally, we conducted an in-depth analysis of the immunological response characteristics, by integrating single-cell RNA/V(D)J sequencing(scRNA/ V(D)J-seq).
Results
Our study demonstrated that heterologous boosting with Ad5-nCoV elicited more mature B cells with higher affinity and activated more abundant immune-related pathways compared to the homologous boosting with CoronaVac. In addition, Ad5-nCoV boosting expanded unique clonal types of B and T cells, whereas CoronaVac boosting led to a small-sized clonal expansion. Furthermore, the utilization of germlines associated with neutralizing antibody were preferentially enriched in recipients with Ad5-nCoV boosting.
Conclusions
Above all, our study gives insights for elaborating the systemic immune landscape of heterologous-boosting COVID-19 immunization by the novel single B cell sorting platform and scRNA/V(D)J-seq technology.
TRIAL REGISTRATION NUMBER
NCT04892459.
Intranasal boosting promotes greater variant-specific response at both the serum and cellular levels than i.m.n. boosting, and ongoing B cell repertoire and mAb analyses will provide mechanistic insight into how vaccination route reshapes clonal selection and maturation, informing rational vaccination design.
Xinyi Liu, Chieh-Yu Liang, Michael S. Diamond· Journal of Immunology· 0 citations
Lower humoral immune responses with increasing time after heterologous mRNA booster vaccination in individuals primed with CoronaVac and may inform future booster strategies are suggested.
H. Harapan, A. P. Ayulinda, Qatrunnada Kamil et al.· Acta Tropica· 0 citations
Introduction Understanding how different COVID-19 vaccine combinations shape long-term immunity is essential for improving durability and guiding booster strategies. Despite extensive characterization of neutralizing antibodies, long-term memory B and T cell responses after homologous and heterologous vaccination regimens remain poorly understood. Methods In this study, peripheral blood mononuclear cells (PBMCs) from 50 individuals were analyzed 12 months after completion of a homologous two-dose primary COVID-19 vaccination series and had received a single booster dose (12-month follow-up). Participants initially received BNT162b2, ChAdOx1 nCoV-19, or CoronaVac as the primary vaccination series, followed by either a homologous booster or a heterologous BNT162b2 booster (ChAdOx1 nCoV-19/BNT162b2 and CoronaVac/BNT162b2). Unvaccinated individuals served as controls. B cell phenotypes were assessed using flow cytometry, while B and T cell recall responses were determined using ELISpot. IgG levels and cytokine/chemokine/growth factor profiles were evaluated using ELISA and Bio-Plex multiplex before and after in vitro stimulation. Results The homologous BNT162b2 vaccination regimen exhibited significantly higher frequencies of memory B cells recognizing the ancestral (Wuhan strain-derived) SARS-CoV-2 Spike protein compared to the ChAdOx1 nCoV-19, CoronaVac, and unvaccinated controls. The CoronaVac/BNT162b2 vaccination regimen demonstrated significantly elevated RBD-specific IgG+ memory B cells and higher stimulated IgG levels, together with the highest IFN-γ-producing T cell responses. Homologous CoronaVac and CoronaVac/BNT162b2 vaccination regimens showed broader cytokine activation, including IL-6, IL-9, IL-15, TNF-α, and other cytokines. IL-6 levels were positively associated with memory B cell frequencies, suggesting a potential association with memory B cell differentiation and maintenance. Discussion Different vaccination regimens were associated with distinct long-term cellular immune profiles under real-world conditions, with both homologous BNT162b2 and heterologous CoronaVac/BNT162b2 vaccination regimens maintaining robust memory B cell signatures and functional recall responses. The results highlight how priming combinations shape the durability and quality of immune memory, supporting the potential utility of mixed-platform booster strategies for sustaining long-term immunity.
N. Che-Kamaruddin, J. Johari, Hasmawati Yahaya et al.· Frontiers in Immunology· 0 citations
The COVID-19 pandemic highlighted the need for vaccines strategies that elicit broad T cell-mediated immunity against emerging viral families. BetaCoronaviruses - including severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome (MERS) and SARS-CoV-2 — pose significant pandemic risks due to their zoonotic potential and genetic diversity. In previous work, we identified conserved Spike T cell epitope regions (S-CTERs) within the ancestral Wuhan S protein sequence that demonstrated strong cross-reactive potential across diverse BetaCoronaviruses.
Here, we investigated whether bivalent vaccination (Beta + Omicron) preferentially enhances T cell responses targeting CTERs and improves cross-reactivity across Betacoronavirus subgenera. PBMC samples were collected at baseline (day 0) and post-vaccination (day 90) from a cohort of 60 adults receiving either the Pfizer or Moderna bivalent vaccine. Antigen-specific CD4+ and CD8+ T cell responses were assessed using a combined activation-induced marker (AIM) and intracellular cytokine (ICS) assay in a 25-colour-flow cytometry panel.
Overall, bivalent vaccination did not increase the response magnitude to spike or the relative fraction of S-CTER responses within total spike responses. A trend toward increased cytokine polyfunctionality was observed post-vaccination, but no significant differences were observed between pre- and post-vaccination samples across CTER pools derived from multiple BetaCoV isolates.
These findings suggest that spike-based bivalent vaccination alone cannot direct a T-cell focused response to achieve broad immunity across the BetaCoronaviruses family. Incorporation of additional protein sequences will likely be required to shift response toward the CTER approach. Understanding how bivalent vaccinations shape T cell recognition of CTER pools will be critical for advancing universal BetaCoronavirus vaccine design.
NIH
Vaccines and Immunotherapy (VAC)
Ziyin Wang, Nematullah Waseem, Naomi Peisajovich et al.· Journal of Immunology· 0 citations
It is shown that a Wuhan-lineage-based multi-antigen VLP vaccine can provide cross-protection against an antigenically divergent SARS-CoV-2 variant that is not fully explained by detectable serum neutralizing activity alone, suggesting the importance of integrated immune responses involving humoral, cellular, and local immune mechanisms.
Seung-Ji Kim, Howon Kim, Seung-Eun Son et al.· Vaccine· 0 citations
Background The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to the COVID-19 pandemic, which resulted in millions of deaths globally and had profound social, economic, and political consequences. Although effective vaccines and antiviral therapies have substantially reduced the global burden of COVID-19, the continued emergence of viral variants highlights the need for next-generation effective vaccine strategies capable of providing broader and more durable immune response. Methods In this work, we provide an immunoinformatic approach for multi-epitope vaccine (MEV) design and prediction. Based on the spike (S) and nucleocapsid (N) proteins of SARS-CoV-2, immunoinformatic methods were used to identify the epitopes for B cells, cytotoxic T lymphocytes (CTL), and helper T lymphocytes (HTL). The B cell, CTL, and HTL epitopes were conjugated with flexible linkers GSG, GSGG, and a Gb-1 peptide conjugated to the C-terminal of the MEV ccandidate. Results The final MEV candidate exhibited favorable predicted characteristics, with a molecular weight of approximately 55.47 kDa and a length of 498 amino acid residues. Computational analyses indicated that the designed construct was antigenic, non-toxic, non-allergenic, and possessed suitable physicochemical properties and predicted solubility, supporting its potential as a vaccine candidate for further investigation. Molecular docking analysis demonstrated favorable interactions between the MEV construct and selected Toll-like receptors (TLRs), while molecular dynamics (MD) simulations suggested the stability of the vaccine-receptor complexes throughout the simulation period. Furthermore, C-ImmSim-based immune simulation predicted the induction of both humoral and cellular immune responses following the proposed immunization schedule. Collectively, these findings highlight the potential of the designed MEV construct as a computationally optimized vaccine candidate and provide a framework for future experimental evaluation. Conclusion This study presents a computationally designed MEV candidate against SARS-CoV-2 by integrating immunoinformatics approaches, structural modeling, molecular docking, molecular dynamics simulations, and immune response prediction. The findings suggest that the proposed MEV construct may possess favorable immunogenic and structural properties; however, experimental validation through in vitro and in vivo studies remains essential to confirm its safety, immunogenicity, and protective efficacy. The proposed approach provides a valuable strategy for accelerating rational vaccine design and may serve as a foundation for future development of experimentally validated vaccine candidates.
