This study developed a high-affinity DNA aptamer, NApt8-3, targeting the coronavirus nucleocapsid (N) protein, which exhibits broad-spectrum anti-inflammatory activity. The researchers further constructed an inhalable cyclic trivalent aptamer-antisense oligonucleotide chimera, circSASON, that significantly suppressed SARS-CoV-2 replication and lung inflammation in mouse models, providing an innovative therapeutic framework to combat future coronavirus pandemics.
Literature Overview
This article, 'Targeting Coronaviral Inflammation: Aptamer-Based Broad-Spectrum Anti-Inflammatory Strategy,' published in Signal Transduction and Targeted Therapy, reviews and summarizes how researchers identified a single-stranded DNA aptamer, NApt8-3, capable of specifically binding the N proteins of multiple coronaviruses through screening. This molecule effectively blocks the interaction between the N protein and the NLRP3 inflammasome, thereby inhibiting virus-induced inflammatory responses. Building on this, the research team further designed a circular trivalent chimera, circSASON, integrating a spike protein-targeting aptamer, an antisense oligonucleotide targeting the N gene, and NApt8-3, enabling infection-dependent delivery. It demonstrated potent dual antiviral and anti-inflammatory effects both in vitro and in vivo. The study validated its therapeutic potential in mouse models, offering a novel strategy for developing rapid-response therapies against future coronavirus variants.Background Knowledge
Coronaviruses such as SARS-CoV, MERS-CoV, and SARS-CoV-2 have triggered multiple global public health crises, with the SARS-CoV-2 pandemic causing a substantial disease burden. Although vaccines and antiviral drugs are available, the virus’s high mutation rate frequently leads to immune escape and drug resistance, particularly undermining spike protein-targeted therapies. Additionally, excessive post-infection inflammatory responses and 'cytokine storms' are key mechanisms driving severe illness and mortality. Current immunomodulators, such as glucocorticoids or IL-6 receptor antagonists, lack specificity and carry risks of secondary infections. Therefore, there is an urgent need to develop broad-spectrum therapies that combine antiviral and anti-inflammatory functions while targeting highly conserved viral regions. The nucleocapsid (N) protein—one of the most conserved structural proteins in coronaviruses—plays critical roles in viral genome packaging and replication, and directly activates the host NLRP3 inflammasome pathway, triggering the release of pro-inflammatory cytokines such as IL-1β and IL-18, making it an ideal target for broad-spectrum intervention. Aptamers, as single-stranded DNA or RNA molecules, can be rapidly selected via SELEX technology and offer advantages including high affinity, low immunogenicity, and ease of modification. They have recently been explored for viral detection and neutralization. However, efficient and targeted in vivo delivery of aptamers remains a major bottleneck for their clinical development. This study addresses this challenge by proposing a novel strategy that leverages the virus’s own infection mechanism for drug delivery, combining antisense oligonucleotides with aptamer functionality to create multifunctional chimeras designed to synergistically inhibit viral replication and inflammatory pathways, offering a rapidly deployable therapeutic solution against future coronavirus threats.
Research Methods and Experiments
The research team first employed microplate-based SELEX technology, using the full-length N protein of SARS-CoV-2 as the target, to screen candidate aptamer NApt8 from a random single-stranded DNA library, and obtained the high-affinity variant NApt8-3 through truncation optimization. ELISA, bio-layer interferometry (BLI), and molecular docking simulations were used to validate its binding capacity and structural basis to N proteins from multiple coronaviruses. Co-immunoprecipitation (Co-IP) and mass spectrometry analysis were performed to elucidate the mechanism by which NApt8-3 inhibits the interaction between the N protein and the NLRP3 inflammasome complex. To achieve functional delivery, the researchers constructed the circular trivalent chimera circSASON, incorporating a spike protein-targeting aptamer (SApt), NApt8-3, and an antisense oligonucleotide targeting the N gene (NASO2), circularized using T4 ligase to enhance stability. Fluorescence labeling experiments verified its specific delivery efficiency in cells infected with SARS-CoV-2 pseudovirus. The inhibitory effects of circSASON on viral replication and inflammatory factor expression were evaluated in Vero E6, Calu-3, and A549 cells, with mechanisms analyzed via qRT-PCR, immunofluorescence, and Western blot. Finally, in a BALB/c mouse model, intranasal administration of circSASON was used to assess its impact on viral load, lung pathological damage, and inflammatory cytokine levels following SARS-CoV-2 Beta variant infection, along with evaluation of its in vivo distribution and immunogenicity.Key Conclusions and Perspectives
Research Significance and Prospects
circSASON represents an innovative multifunctional antiviral-anti-inflammatory chimera whose design cleverly exploits the virus’s own infection mechanism for targeted drug delivery, enhancing therapeutic specificity and reducing off-target effects. NApt8-3, as the first N protein-targeting aptamer validated to have broad anti-inflammatory function in an animal model, expands the application frontier of aptamers in antiviral therapy and provides a rapid-response drug development platform against future high-pathogenicity coronaviruses.
This study not only validates the feasibility of targeting the N protein–NLRP3 pathway to control inflammation associated with coronavirus infection but also offers new insights for developing broad-spectrum anti-inflammatory therapies against other RNA viruses. The circular structure of circSASON enhances nuclease resistance and prolongs its duration of action, although its in vivo half-life remains short. Future chemical modifications could further improve its stability and systemic exposure, facilitating clinical translation. Moreover, this platform can be rapidly adapted to emerging coronavirus variants, demonstrating high modularity and scalability, making it a strong candidate strategy against future pandemic threats.
Conclusion
This study developed a high-affinity DNA aptamer, NApt8-3, targeting the coronavirus nucleocapsid (N) protein, capable of broadly binding N proteins from multiple coronaviruses and blocking their interaction with the NLRP3 inflammasome, thereby effectively suppressing virus-induced inflammatory responses. Based on this, the research team constructed a circular trivalent chimera, circSASON, integrating viral targeting, gene silencing, and anti-inflammatory functions, which, when administered intranasally, significantly reduced SARS-CoV-2 viral load and alleviated lung inflammation in mouse models, demonstrating excellent therapeutic potential. This strategy not only provides a broad-spectrum candidate drug with dual antiviral and anti-inflammatory functions but also establishes a modular platform capable of rapid response to emerging coronavirus variants. Although the current molecule’s metabolic stability requires improvement, its low immunogenicity and efficient targeted delivery lay a solid foundation for future optimization. This work offers innovative insights for addressing future coronavirus pandemics, emphasizing the importance of co-targeting conserved viral proteins and host inflammatory pathways, and holds significant translational medical value.
