Are there differences in glycosylation or post-translational modifications of spike protein made by infected cells versus vaccine-expressing cells?
Executive summary
Cell type and production method change spike glycosylation and other post‑translational modifications (PTMs): published comparisons show recombinant spikes made in HEK293 or CHO cells differ in N‑glycan types across the 22 N‑glycosylation sites, and recombinant lab spikes can reproduce many viral glycan features but not always identically [1] [2] [3]. Reviews and experimental work stress that O‑glycosylation, site occupancy and complex vs. high‑mannose glycan composition vary with expression host and manufacturing process — factors that can alter antigenicity and immune focusing [4] [3] [5].
1. Different factories, different trims — how host cells change spike glycans
Cells install glycans using host enzymes; therefore spike produced in a virus‑infected airway epithelial cell, in HEK293 kidney cells, or in CHO ovary cells will bear different glycan mixtures. Direct analyses show HEK‑derived recombinant S1/RBD glycans are similar to one another but differ from virus‑derived spike produced in Vero cells, and a side‑by‑side study reported important differences in N‑glycan variety and types between HEK and CHO expression systems across the 22 N‑glycosylation sites [3] [1]. An international comparison of lab‑made recombinant spikes concluded many batches “mimic key features” of virion glycosylation, but that does not imply perfect identity [2].
2. Not just N‑glycans — O‑glycans and other PTMs matter and vary
Reviews and targeted studies emphasize O‑glycosylation is more variable and strongly dependent on the cell’s repertoire of transferases; this can change site usage and glycan cores, with potential consequences for immune recognition [4]. Authors also note that post‑translational processing (cleavage, furin processing, folding and potential ISGylation/ubiquitin‑related marks) differs between an infected cell producing virions and cells that only express spike after vaccination or in biomanufacturing — available sources discuss these possibilities but also highlight that data on vaccine‑produced spike glycosylation in vivo remain limited [6] [4].
3. Why glycan differences matter for immunity and vaccine design
Glycans shield or expose protein epitopes and can steer antibody specificity. Experimental manipulation of subunit vaccine glycosylation in mice altered humoral focusing and neutralizing antibody levels; the presence of complex glycans correlated with higher neutralizing responses in that model [5]. Glycosylation changes accompanying viral evolution also affect antigenicity and antibody binding, underlining that both sequence and PTMs shape immune outcomes [7].
4. Lab spikes can approximate the virus, but production choices leave fingerprints
Multiple laboratories produced recombinant spikes that recapitulated many of the authentic virus’s glycan signatures, a result useful for vaccine and therapeutic work — but the same reports caution that manufacturing host cells and secretion pathways introduce distinctive glycosylation and secretion patterns that may have immunological consequences [2] [8]. Analytical advances (mass spectrometry, I2MS, new glycan‑fingerprinting methods) have clarified heterogeneity and can detect differences between intact viral spike, cell‑derived whole‑virus spike and recombinant forms [9] [10].
5. What the literature does not settle — in vivo vaccine‑produced spike PTMs
Several commentary and review pieces point out that data on the precise structure, conformation and glycosylation of spike synthesized by human cells after mRNA vaccination are scarce; authors call for more direct structural and glycoproteomic studies of vaccine‑expressed spike in human tissues and circulation [6]. Claims about long‑term persistence of vaccine mRNA or circulating vaccine‑derived spike are discussed in the literature, but those are separate questions from site‑specific glycosylation patterns and require different datasets [11] [12].
6. Practical takeaways and competing perspectives
Consensus: host cell and production route cause measurable glycosylation and PTM differences that can affect antigenicity and immune focusing [1] [5] [3]. Some studies show recombinant spikes can closely mimic virion glycans [2]. Gaps remain: precise maps of vaccine‑expressed spike PTMs in human tissues are limited in current reporting, and reviews urge targeted in vivo glycoproteomics to resolve whether vaccine‑produced spike differs functionally from viral spike in people [6].
Limitations: this summary uses only the supplied sources; questions about clinical implications beyond antigenicity — for example, linkage to adverse events or persistence claims — are addressed in other literature and are only partially covered in the provided set [12] [11].