DNA origami vaccines could be the next leap beyond mRNA

The COVID-19 pandemic irrevocably propelled messenger RNA (mRNA) vaccine technology into the global scientific and public consciousness, demonstrating unprecedented speed and efficacy in combating a novel pathogen. Following a rapid development and clinical trial phase, the world witnessed a monumental achievement on December 8, 2020, with the administration of the first COVID-19 mRNA vaccine. The subsequent rollout of these innovative vaccines marked a turning point in the pandemic response, with researchers later estimating through sophisticated modeling that these interventions prevented a staggering minimum of 14.4 million deaths worldwide within their inaugural year alone. This profound impact underscored the transformative potential of mRNA technology, inspiring a global pivot in vaccine research.

The mRNA Revolution and Its Unforeseen Limitations

The success of COVID-19 mRNA vaccines spurred an ambitious wave of research, with scientists rapidly embarking on the development of mRNA-based vaccines for a diverse array of other infectious diseases. Clinical trials are currently underway, targeting pervasive threats such as influenza virus, Respiratory Syncytial Virus (RSV), HIV, Zika virus, Epstein-Barr virus, and even the challenging tuberculosis bacteria. The appeal of mRNA lies in its modularity and speed of development; once the genetic sequence of a target antigen is known, an mRNA vaccine can be designed and manufactured relatively quickly compared to traditional vaccine platforms. This inherent adaptability makes mRNA an attractive candidate for addressing emerging pathogens and rapidly evolving viruses.

However, despite their groundbreaking success and ongoing expansion, the intensive, real-world application and scrutiny of COVID-19 mRNA vaccines have simultaneously brought to light several important limitations. These challenges underscore the continuous need for diversified and innovative vaccine strategies to effectively prepare for and respond to future infectious disease threats.

One significant challenge identified is the variability in immune protection generated by COVID-19 mRNA vaccines, which can differ widely from person to person. Factors such as age, underlying health conditions, and individual immune system characteristics contribute to this heterogeneous response. Furthermore, the duration of protection afforded by these vaccines is not indefinite, often necessitating booster doses to maintain adequate immunity. This issue is compounded by the relentless evolutionary pressure on SARS-CoV-2, which continually produces new variants capable of partially evading existing immune defenses. Consequently, vaccines frequently require updating to target these emergent strains, leading to a perpetual cycle of adaptation and deployment.

Beyond immunological considerations, practical hurdles in the manufacturing and distribution of mRNA vaccines have also emerged. The production process for mRNA vaccines is inherently complex and expensive, involving intricate biochemical steps to synthesize and purify the mRNA molecules. A critical aspect of their formulation involves packaging the mRNA into lipid nanoparticles (LNPs), which protect the delicate mRNA from degradation and facilitate its delivery into cells. Controlling the precise number of mRNA molecules packaged into each LNP remains a technical challenge, impacting consistency and yield. Moreover, mRNA vaccines are notorious for their stringent cold storage requirements, typically demanding ultra-cold temperatures (e.g., -70°C to -20°C). This "cold chain" requirement poses substantial logistical and financial burdens, particularly in regions with limited infrastructure, hindering equitable global distribution. Concerns about potential unintended off-target effects, though rare, also necessitate ongoing vigilance and research into refining vaccine specificity. Overcoming these multifaceted limitations is paramount for enhancing global preparedness and response capabilities against future pandemics.

Introducing DoriVac: A DNA Origami Nanotechnology Platform

In pursuit of solutions to these challenges, a multidisciplinary research team comprising experts from the Wyss Institute at Harvard University, Dana-Farber Cancer Institute (DFCI), and collaborating institutions has explored a radically different approach. Their innovation centers around a novel DNA origami nanotechnology platform named DoriVac, which uniquely functions as both a vaccine and an intrinsic adjuvant. This dual functionality is a significant departure from many traditional vaccine designs that require separate adjuvant components to boost immune responses.

The researchers meticulously designed DoriVac vaccines to target a specific peptide region known as HR2. This conserved region is found within the critical spike proteins of multiple pathogenic viruses, including SARS-CoV-2, HIV, and Ebola. The strategic targeting of a conserved region like HR2 holds immense promise for developing broadly protective vaccines that could potentially offer immunity against multiple variants or even different species of viruses, a significant advantage over strain-specific vaccines.

Initial preclinical testing in mouse models yielded highly encouraging results. The SARS-CoV-2 HR2 DoriVac vaccine successfully triggered robust immune responses, encompassing both antibody-driven (humoral) activity and T cell-driven (cellular) activity. Humoral immunity, mediated by antibodies, is crucial for neutralizing viruses circulating in the bloodstream, while cellular immunity, driven by T cells, is vital for eliminating infected cells and providing long-term protection. The activation of both arms of the immune system suggests a comprehensive and durable protective response.

To further validate the platform’s potential in a more human-relevant context, the team leveraged the Wyss Institute’s cutting-edge microfluidic human Organ Chip technology. This innovative system simulates a human lymph node in vitro, providing a sophisticated preclinical model that bridges the gap between animal studies and human clinical trials. Within this advanced system, the SARS-CoV-2 HR2 DoriVac vaccine also generated strong antigen-specific immune responses in human cells, mirroring the promising results observed in mice.

A critical phase of the study involved a direct head-to-head comparison between a DoriVac vaccine carrying the same spike protein variant and established SARS-CoV-2 mRNA vaccines delivered through lipid nanoparticles. This rigorous comparison in human models revealed that the DoriVac vaccine produced a similarly potent immune activation. However, the DNA origami vaccine demonstrated clear advantages in terms of stability, and importantly, proved easier to store and manufacture. These seminal findings, highlighting DoriVac’s efficacy and superior practical attributes, were formally reported in the esteemed scientific journal Nature Biomedical Engineering.

Precision Engineering: The DoriVac Advantage

Dr. William Shih, a co-corresponding author and Core Faculty member at the Wyss Institute, whose group pioneered the foundational concept of this novel vaccine, articulated the platform’s transformative potential. "With the DoriVac platform, we have developed an extremely flexible chassis with a number of critical advantages, including an unprecedented control over vaccine composition, and the ability to program immune recognition in targeted immune cells on a molecular level to achieve better responses," stated Dr. Shih, who also holds professorships at Harvard Medical School and DFCI. He emphasized, "Our study demonstrates DoriVac’s versatility and potential by taking a close look at the immune changes that are required to fight infectious viruses." This statement underscores the core principle of DoriVac: a level of molecular precision in vaccine design previously unattainable.

The DoriVac platform was first introduced by Dr. Shih’s team at the Wyss Institute and Dana-Farber in 2024, initially envisioned as a DNA nanotechnology-based vaccine platform with broad applications, particularly in oncology. Dr. Yang (Claire) Zeng, M.D., Ph.D., who spearheaded this groundbreaking effort alongside collaborators, demonstrated DoriVac’s remarkable capability to precisely present immune-stimulating adjuvant molecules to cells at the nanoscale. This exquisite control over molecular arrangement is a hallmark of DNA origami technology, allowing researchers to engineer structures with atomic precision.

Earlier studies, conducted in tumor-bearing mice, compellingly illustrated that these DNA origami vaccines elicited significantly stronger immune responses compared to vaccine formulations lacking the sophisticated DNA origami structure. The architecture of DoriVac vaccines is elegant yet powerful: they are meticulously constructed from tiny, self-assembling square DNA nanostructures. One side of these nanostructures is engineered to display adjuvant molecules, arranged at carefully controlled nanometer distances, which is critical for optimal immune cell stimulation. The opposing side presents selected antigens, such as peptides or proteins derived from tumors or, in the case of the new study, from pathogens.

Dr. Zeng, who is also the first and co-corresponding author on the new study and now the cofounder and CEO/CTO of DoriNano, reflected on the platform’s evolution: "While we were developing the platform for cancer applications, the COVID-19 pandemic was still moving with full force. So, the question quickly arose whether DoriVac’s superior adjuvant activity could also be leveraged in infectious disease settings." This timely pivot highlights the responsiveness of scientific research to pressing global health crises. Dr. Zeng is now actively leading the translation of this promising technology into clinical applications.

To thoroughly explore this idea, Dr. Zeng and co-first author Dr. Olivia Young, a former graduate student in Dr. Shih’s group, initiated a crucial collaboration with Dr. Donald Ingber’s team at the Wyss Institute. Dr. Ingber’s group is renowned for its pioneering work in antiviral innovation, utilizing advanced AI-driven and multiomics approaches in conjunction with sophisticated microfluidic human Organ Chip systems. Working in concert with co-first author Dr. Longlong Si, a former postdoctoral researcher in Dr. Ingber’s lab, the researchers successfully developed DoriVac vaccines specifically targeting SARS-CoV-2, HIV, and Ebola. These vaccine candidates were designed to present the HR2 peptides, which serve as highly conserved antigens within the respective viral spike proteins, offering the potential for broad-spectrum protection.

Dr. Zeng elaborated on the significant immunological findings from the mouse studies: "Our analysis of the immune responses provoked by these first DoriVac vaccines in mice led to several encouraging observations, including significantly greater and broader activation of humoral and cellular immunity across a range of relevant immune cell types than what the origami-free antigens and adjuvants could produce." She further explained, "We found that the numbers of antibody-producing B cells, activated antigen-presenting dendritic cells (DCs), and antigen-specific memory and cytotoxic T cell types that are vital for long-term protection were all increased, especially in the case of the SARS-CoV-2 HR2." These detailed immunological insights underscore DoriVac’s capacity to induce a robust and comprehensive immune response, crucial for effective and enduring protection against viral pathogens.

Bridging the Translational Gap: From Mouse to Human Models

A perennial challenge in the complex landscape of vaccine development lies in the inherent differences between species. Immune responses observed in murine models, while informative, often do not fully recapitulate the intricate biological processes occurring in humans. This translational gap has historically been a major bottleneck, leading to the failure of many promising treatments during subsequent human clinical trials. To mitigate this risk and enhance the predictive power of their preclinical findings, the DoriVac team ingeniously employed a human lymph node-on-a-chip (human LN Chip). This sophisticated in vitro system is engineered to mimic critical aspects of the human immune system, providing a more relevant testing ground than traditional animal models.

This advanced human LN Chip system, significantly refined and advanced by co-first author Min Wen Ku and co-corresponding author Dr. Girija Goyal, Director of Bioinspired Therapeutics at the Wyss Institute, proved instrumental in validating DoriVac’s potential. The system demonstrated that the SARS-CoV-2-HR2 DoriVac vaccine effectively activated human dendritic cells (DCs) and significantly boosted their production of inflammatory cytokines when compared to origami-free vaccine components. Furthermore, the DoriVac vaccine led to an increased proliferation of both CD4+ and CD8+ T cells, cell types critical for orchestrating and executing protective immune functions. These findings in a human-relevant model further strengthen the platform’s potential for successful translation into human clinical applications.

Dr. Donald Ingber, a co-corresponding author and the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, as well as the Hansjörg Wyss Professor of Biologically Inspired Engineering at Harvard John A. Paulson School of Engineering and Applied Sciences, highlighted the profound impact of this innovative testing approach. "The predictive capabilities of human LN Chips gave us an ideal testing ground for DoriVac vaccines and the induced, antigen-specific immune cell profiles and activities very likely reflect those that would occur in human recipients of the vaccines," he stated. Dr. Ingber further emphasized, "This convergence of technologies enabled us to dramatically raise the chances of success for a new class of vaccines and create a new testbed for future vaccine developments." This synergistic approach of advanced nanotechnology and cutting-edge human organ-on-a-chip technology represents a significant leap forward in preclinical vaccine evaluation.

DoriVac Versus mRNA: A Head-to-Head Comparison

To provide a comprehensive assessment of DoriVac’s capabilities, the researchers undertook a direct comparison with the currently dominant mRNA vaccine technology. Led by Dr. Zeng and co-author Qiancheng Xiong, the team evaluated a DoriVac vaccine engineered to present the full SARS-CoV-2 spike protein. This DoriVac formulation was then directly pitted against commercially available mRNA lipid nanoparticle (LNP) vaccines from Moderna and Pfizer/BioNTech, which encode the identical spike protein antigen.

Using a standard booster immunization approach in mice, both the DoriVac platform and the mRNA-LNP vaccines produced remarkably similar antiviral T cell and antibody-producing B cell responses. This equivalency in immune activation is a crucial finding, demonstrating that DoriVac can achieve the same level of immunological potency as the established mRNA vaccines, a testament to its robust design and mechanism of action.

Dr. Shih underscored the broader implications of this comparison: "This underscored DoriVac’s potential as a DNA nanotechnology-enabled, self-adjuvanted vaccine platform." He then elaborated on DoriVac’s distinct advantages that could address the logistical and manufacturing hurdles associated with mRNA vaccines. "But DoriVac vaccines have a number of other advantages: they don’t have the same cold-chain requirements as mRNA-LNP vaccines do and thus could be distributed much more effectively, especially in under-resourced regions; and they could overcome some of the enormous manufacturing complexities of LNP-formulated vaccines, to name two major ones." The elimination of ultra-cold storage requirements would revolutionize vaccine distribution, particularly in low-income countries where such infrastructure is scarce or non-existent, thereby fostering greater global vaccine equity. Furthermore, the inherent stability and potentially simpler manufacturing process of DNA origami structures could significantly reduce production costs and increase accessibility. Recent studies conducted at DoriNano have also provided promising evidence regarding DoriVac’s safety profile, a critical consideration for any new vaccine platform.

Broader Impact and Future Implications

The emergence of the DoriVac platform represents a significant stride in vaccine innovation, offering a compelling alternative to existing technologies and addressing several critical limitations. Its ability to generate robust immune responses comparable to mRNA vaccines while offering superior stability, simplified storage, and potentially easier manufacturing could redefine global vaccine preparedness and response strategies.

• Global Health Equity: The most immediate and profound impact of DoriVac’s reduced cold-chain requirements lies in its potential to democratize vaccine access. Eliminating the need for ultra-cold freezers would enable far wider distribution in remote and under-resourced areas, accelerating vaccination campaigns during pandemics and routine immunization efforts. This could bridge significant gaps in global health equity, ensuring that life-saving vaccines reach every corner of the world.
• Enhanced Pandemic Preparedness: A vaccine platform that is stable at ambient temperatures and easier to produce could drastically cut down the time from pathogen identification to widespread vaccine deployment. This agility would be invaluable in containing future outbreaks more swiftly and effectively, minimizing economic disruption and saving countless lives.
• Universal Vaccine Development: The strategic targeting of conserved viral regions like HR2 opens avenues for developing "universal" vaccines. Such vaccines could offer protection against multiple variants of a single virus (e.g., SARS-CoV-2 variants) or even against entire families of viruses (e.g., pan-influenza, pan-coronavirus). This broad-spectrum immunity would reduce the need for constant vaccine updates, simplifying public health campaigns and offering more durable protection.
• Cost-Effectiveness and Scalability: While still in preclinical stages, the promise of simpler manufacturing processes for DoriVac could translate into lower production costs. Combined with reduced logistical expenses from cold chain elimination, this could make vaccines more affordable and scalable, particularly for diseases requiring mass immunization.
• Precision Medicine in Vaccinology: The unparalleled control over vaccine composition and molecular presentation offered by DNA origami nanotechnology heralds a new era of precision vaccinology. Researchers can meticulously engineer vaccine structures to elicit specific types of immune responses, tailoring interventions to specific pathogens or patient populations.

While the findings are exceptionally promising, it is crucial to recognize that DoriVac is currently in preclinical development. The next critical steps will involve rigorous testing in human clinical trials to confirm its safety, immunogenicity, and efficacy in diverse populations. If successful, DoriVac could usher in a new generation of vaccines, complementing and potentially surpassing existing technologies, thereby bolstering humanity’s defenses against current and future infectious disease threats.

The extensive collaborative research was made possible through funding from various prestigious organizations, including the Director’s Fund and Validation Project program of the Wyss Institute; the Claudia Adams Barr Program at DFCI; the National Institutes of Health (U54 grant CA244726-01); the US-Japan CRDF global fund (grant R-202105-67765); the National Research Foundation of Korea (grants MSIT, RS-2024-00463774, RS-2023-00275456); the Intramural Research Program of the Korea Institute of Science and Technology (KIST); and the Bill and Melinda Gates Foundation (INV-002274). The study’s authorship includes Sylvie Bernier, Hawa Dembele, Giorgia Isinelli, Tal Gilboa, Zoe Swank, Su Hyun Seok, Anjali Rajwar, Amanda Jiang, Yunhao Zhai, LaTonya Williams, Caleb Hellman, Chris Wintersinger, Amanda Graveline, Andyna Vernet, Melinda Sanchez, Sarai Bardales, Georgia Tomaras, Ju Hee Ryu, and Ick Chan Kwon, reflecting the broad expertise and collaborative spirit driving this innovative scientific endeavor.