mRNA vaccines have played a pivotal role in curbing the COVID-19 pandemic. However, mRNA molecules are inherently unstable and prone to degradation—a feature that, while beneficial for safety, can limit their duration of action and reduce vaccine efficacy.
The poly(A) tail, located at the 3′ end of mRNA, is crucial for mRNA stability and protein production. Although the metabolic impact of vaccines on poly(A) tails remains understudied, it is widely assumed that the stability of therapeutic mRNA largely depends on the rate of deadenylation (poly(A) tail shortening).
Groundbreaking Discovery in Nature
On April 17, 2025, a groundbreaking study published in Nature by researchers from the International Institute of Molecular and Cell Biology in Warsaw, the University of Warsaw, the Medical University of Warsaw, and the Institute of Biochemistry and Biophysics of the Polish Academy of Sciences revealed a surprising discovery. In their paper, “Re-adenylation by TENT5A enhances efficacy of SARS-CoV-2 mRNA vaccines,” the team demonstrated that BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) vaccines induce TENT5A poly(A) polymerase to extend poly(A) tails, thereby stabilizing in vitro-transcribed (IVT) mRNA encoding secreted proteins and enhancing immunogenicity. Unlike the previously assumed deadenylation mechanism, TENT5A-mediated re-adenylation represents a universal mRNA stabilization mechanism with vast medical potential.
Deadenylation: The Shortening of mRNA Lifespan
Using nanopore sequencing, researchers first examined the poly(A) tails of Moderna’s mRNA-1273 and Pfizer-BioNTech’s BNT162b2. They found that:
- mRNA-1273 has a ~100-nt poly(A) tail followed by an mΨCmΨAG sequence.
- BNT162b2 has a composite poly(A) tail, with all uridines replaced by N1-methylpseudouridine (mΨ).
In HEK293T and A549 cell lines, mRNA-1273 underwent rapid deadenylation when the mΨCmΨAG sequence was absent, leading to significant poly(A) tail shortening and reduced vaccine expression over time. In contrast, BNT162b2 exhibited slower deadenylation and greater stability. Further experiments confirmed that deadenylation-driven poly(A) shortening limits mRNA lifespan.
Re-adenylation: Extending mRNA Stability
When mRNA-1273 was injected into mice, the median poly(A) tail length increased from 100 nt to 114 nt within 24 hours. Enhanced direct RNA sequencing (eDRS) at the injection site confirmed poly(A) elongation, particularly in F4/80+CD64+ macrophages—but not in dendritic cells (DCs), where deadenylation dominated, leading to rapid mRNA decay.
Interestingly, BNT162b2 induced only minor poly(A) tail extension, suggesting differences in re-adenylation efficiency between the two vaccines.
Figure 1: mRNA-1273 poly(A) tail extension in vivo and in macrophages1,2
TENT5A: The Key Poly(A) Polymerase
In mRNA-1273-treated mouse bone marrow-derived macrophages (mBMDMs), not only the vaccine mRNA but also 124 endogenous transcripts showed poly(A) tail elongation (average +20 nt in 24 h)—particularly those related to immune responses.
Strikingly, TENT5A, a cytoplasmic poly(A) polymerase, was upregulated in macrophages post-vaccination, while other non-canonical poly(A) polymerases remained unchanged. This led researchers to hypothesize that TENT5A mediates re-adenylation.
To test this, they used TENT5A-knockout mice:
- mRNA-1273 poly(A) tails shortened, reducing stability.
- Anti-spike IgG levels dropped significantly after vaccination.
- BNT162b2 showed a milder IgG reduction, suggesting its re-adenylation is less TENT5A-dependent.
These findings confirm that TENT5A is essential for mRNA-1273 re-adenylation and vaccine efficacy. Notably, re-adenylation efficiency depends on capping methods, coding sequences, and UTRs, but not poly(A) tail composition itself.
Figure 2: mRNA-1273 induces innate immunity and TENT5A expression2,3
Implications for mRNA Therapeutics
This study reveals for the first time that:
- TENT5A-mediated re-adenylation extends poly(A) tails (up to 200 nt) in macrophages, boosting mRNA stability and antigen production.
- Re-adenylation efficiency varies between vaccines—BNT162b2 exhibits weaker effects, possibly due to lower membrane-associated protein content.
- This mechanism applies broadly to ER-targeted secretory proteins (e.g., ovalbumin, Zika virus, and malaria antigens).
These insights open new avenues for optimizing mRNA vaccine design and developing next-generation mRNA therapeutics. Additionally, the study highlights macrophages as key players in mRNA vaccine potency, offering new directions for future research.
Practical Applications — How to Enhance Your mRNA Project
If you are developing mRNA vaccines or therapeutics, improving stability starts with high-quality mRNA cap structures and optimized poly(A) tails.
Our lab-grade reagents are designed for maximum stability, efficient translation, and regulatory compliance:
- Premium mRNA Cap Analog Products — ensuring strong ribosome recruitment and translation efficiency.
- High-Purity Poly(A) Tail Reagents — engineered for extended half-life and enhanced protein yield.
- Modified Nucleosides — Including N1-methylpseudouridine (m1Ψ), pseudouridine (Ψ), and other modifications to reduce innate immune activation and increase mRNA translation efficiency.
- High-Purity Nucleotides — GMP-compliant ATP, GTP, CTP, and UTP for reliable in vitro transcription, ensuring high yield and superior mRNA quality.
Contact us for free technical consultation on mRNA design and stability optimization.
References
- Image retrieved from Figure 2 “The poly(A) tail of mRNA-1273 is extended in macrophages in vivo and in vitro.,” Krawczyk, Paweł S., et al., 2025, used under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). The original image was modified by extracting and using only part a, and the title was changed to ” mRNA-1273 poly(A) tail extension in vivo and in macrophages”
- Krawczyk, Paweł S., et al. “Re-adenylation by TENT5A enhances efficacy of SARS-CoV-2 mRNA vaccines.” Nature (2025): 1-9.
- Image retrieved from Figure 3 “mRNA-1273 induces the innate immune response and the expression of TENT5A.,” Krawczyk, Paweł S., et al., 2025, used under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). The original image was modified by extracting and using only part a, and the title was changed to “mRNA-1273 induces innate immunity and TENT5A expression”