By Hendra Lukman 
The unprecedented success of messenger RNA (mRNA) vaccines in combating the COVID-19 pandemic, marked by the first global administration on December 8, 2020, catapulted this revolutionary technology into the scientific and public consciousness. Modeling studies later revealed a staggering impact, estimating that these vaccines prevented at least 14.4 million deaths worldwide within their inaugural year. This remarkable achievement spurred a surge of research into expanding mRNA technology for a diverse array of infectious diseases, with ongoing clinical trials targeting influenza, Respiratory Syncytial Virus (RSV), HIV, Zika, Epstein-Barr virus, and even tuberculosis. However, the very successes of COVID-19 mRNA vaccines also illuminated critical limitations, underscoring the persistent need for innovative vaccine strategies that address performance variability, logistical challenges, and the ever-evolving nature of pathogens.
Navigating the Hurdles of mRNA Vaccine Technology
Despite their monumental contributions, current mRNA vaccine platforms face several significant challenges. One primary concern is the inherent variability in immune protection elicited by these vaccines, which can differ substantially from person to person. Furthermore, the duration of this immunity is not indefinite, necessitating booster shots. This limitation is exacerbated by the rapid evolution of viruses like SARS-CoV-2, which continuously generate new variants capable of partially evading established immune defenses, thus requiring frequent vaccine updates.
Beyond performance, practical hurdles present substantial obstacles. The manufacturing process for mRNA vaccines is inherently complex and costly. Precisely controlling the quantity of mRNA molecules encapsulated within lipid nanoparticles, a critical step for effective delivery, remains a technical challenge. These vaccines also have stringent cold-chain requirements for storage and transportation, limiting their accessibility in resource-limited settings. Moreover, there is an ongoing need to thoroughly assess and mitigate potential unintended off-target effects. Overcoming these multifaceted limitations is crucial for enhancing global preparedness and response capabilities to future infectious disease threats.
Introducing DoriVac: A DNA Origami Nanotechnology Breakthrough
In response to these pressing challenges, a multidisciplinary team from the Wyss Institute at Harvard University, the Dana-Farber Cancer Institute (DFCI), and collaborating institutions has explored a fundamentally different approach: the DoriVac platform. This innovative DNA origami nanotechnology platform functions as a dual-purpose vaccine and adjuvant, offering a compelling alternative to existing technologies.
The DoriVac vaccines are ingeniously designed to target a conserved peptide region, known as HR2, found within the spike proteins of a broad spectrum of viruses, including SARS-CoV-2, HIV, and Ebola. This conserved region is less prone to mutation, offering the potential for broader and more durable protection. In preclinical studies conducted in mice, a SARS-CoV-2 HR2 DoriVac vaccine elicited robust immune responses, characterized by both potent antibody-driven (humoral) immunity and vigorous T cell-driven (cellular) activity.
To bridge the gap between animal models and human physiology, the researchers employed the Wyss Institute’s sophisticated microfluidic human Organ Chip technology. This in vitro system meticulously simulates a human lymph node, providing a more accurate preclinical model of human immune responses. Within this advanced human lymph node-on-a-chip system, the SARS-CoV-2 HR2 DoriVac vaccine demonstrated its capacity to generate strong antigen-specific immune responses in human cells, mirroring the promising results observed in mice.
In a pivotal direct comparison against established SARS-CoV-2 mRNA vaccines delivered via lipid nanoparticles, a DoriVac vaccine encoding the same spike protein variant induced similarly potent immune activation in human models. Crucially, the DNA origami-based vaccine exhibited distinct advantages in terms of stability and demonstrated greater ease of storage and manufacturing. These groundbreaking findings were recently published in the esteemed journal Nature Biomedical Engineering, signaling a significant advancement in vaccine development.
William Shih, Ph.D., a co-corresponding author on the study and a Core Faculty member at the Wyss Institute, highlighted the platform’s transformative potential. "With the DoriVac platform, we have developed an extremely flexible chassis with a number of critical advantages, including 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. "Our study demonstrates DoriVac’s versatility and potential by taking a close look at the immune changes that are required to fight infectious viruses."
The Architecture of DNA Origami Vaccines: Precision at the Nanoscale
The genesis of the DoriVac platform traces back to 2024, when Dr. Shih’s team at the Wyss Institute and DFCI introduced it as a versatile DNA nanotechnology-based vaccine solution with broad applicability. Yang (Claire) Zeng, M.D., Ph.D., who spearheaded this pioneering effort alongside collaborators, demonstrated DoriVac’s ability to precisely present immune-stimulating adjuvant molecules to cells at the nanoscale, a level of control previously unattainable.
Earlier investigations in tumor-bearing mice had already established DoriVac’s superiority in eliciting stronger immune responses compared to vaccine versions lacking the DNA origami structure. The construction of DoriVac vaccines involves minuscule, self-assembling square DNA nanostructures. One facet of these nanostructures is meticulously engineered to display adjuvant molecules at precisely controlled nanometer distances, while the opposing facet presents carefully selected antigens, such as peptides or proteins derived from tumors or pathogens.
"While we were developing the platform for cancer applications, the COVID-19 pandemic was still moving with full force," explained Dr. Zeng, the first and co-corresponding author on the new study and now co-founder and CEO/CTO of DoriNano, a company dedicated to translating this technology into clinical applications. "So, the question quickly arose whether DoriVac’s superior adjuvant activity could also be leveraged in infectious disease settings."
To explore this exciting possibility, Dr. Zeng and co-first author Olivia Young, Ph.D., a former graduate student in Dr. Shih’s group, collaborated with the laboratory of Donald Ingber at the Wyss Institute. Dr. Ingber’s team specializes in antiviral innovation, leveraging artificial intelligence-driven and multiomics approaches, complemented by microfluidic human Organ Chip systems. Working in tandem with co-first author Longlong Si, Ph.D., a former postdoctoral researcher in Dr. Ingber’s lab, the researchers successfully developed DoriVac vaccines targeting SARS-CoV-2, HIV, and Ebola. These vaccines strategically present HR2 peptides, which function as conserved antigens within the highly variable viral spike proteins.
"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," stated Dr. Zeng. "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," she elaborated.
From Preclinical Mouse Models to Predictive Human Systems
A persistent challenge in vaccine development is the frequent disconnect between immune responses observed in mice and their predictability in humans. This translational gap has historically led to the failure of numerous promising therapeutic candidates during clinical trials. To enhance the predictive accuracy of their findings, the research team rigorously tested DoriVac vaccines using a human lymph node-on-a-chip (human LN Chip) system. This advanced technology is designed to closely mimic crucial aspects of the human immune system.
This sophisticated microfluidic system, further advanced by co-first author Min Wen Ku and co-corresponding author Girija Goyal, Ph.D., Director of Bioinspired Therapeutics at the Wyss Institute, demonstrated that the SARS-CoV-2-HR2 DoriVac vaccine effectively activated human dendritic cells. It also significantly amplified their production of inflammatory cytokines when compared to non-origami formulations. Furthermore, the vaccine increased the population of CD4+ and CD8+ T cells exhibiting multiple protective functions, providing robust support for the platform’s considerable potential for human application.
"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," remarked co-corresponding author Donald Ingber, M.D., Ph.D. Dr. Ingber, who also holds distinguished professorships at Harvard Medical School, Boston Children’s Hospital, and the Harvard John A. Paulson School of Engineering and Applied Sciences, emphasized the synergistic impact of this technological convergence. "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."
A Direct Confrontation: DoriVac Versus mRNA Vaccines
In a crucial head-to-head evaluation, the researchers assessed a DoriVac vaccine engineered to present the full SARS-CoV-2 spike protein. Spearheaded by Dr. Zeng and co-author Qiancheng Xiong, the team conducted a direct comparison with Moderna and Pfizer/BioNTech mRNA lipid nanoparticle (LNP) vaccines that encode the identical spike protein. This comparison was performed using a standard booster regimen in mice.
The results of this rigorous comparison revealed that both vaccine types elicited comparable antiviral T cell and antibody-producing B cell responses. This finding underscores DoriVac’s significant potential as a self-adjuvanted vaccine platform powered by DNA nanotechnology.
"This underscored DoriVac’s potential as a DNA nanotechnology-enabled, self-adjuvanted vaccine platform," Dr. Shih reiterated. "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." Preliminary safety studies conducted by DoriNano have further indicated a promising safety profile for DoriVac vaccines.
The foundational research team included 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. This comprehensive study was made possible through substantial funding from various prestigious sources, 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 collective efforts and financial backing represent a significant investment in the future of vaccine technology, with DoriVac poised to play a pivotal role in addressing global health challenges.