In a paper published today in the Journal of Clinical Investigation, a research team at Johns Hopkins Medicine and the Johns Hopkins Bloomberg School of Public Health reports developing a therapeutic intranasal (nose-delivered) DNA vaccine against tuberculosis (TB) that fuses two genes with the goal of directing the immune system to fight drug-tolerant bacterial "persisters" that can survive prolonged antibiotic therapy and contribute to disease relapse.
A scourge for at least the past 6,000 years, TB is estimated by the World Health Organization (WHO) to be a latent, symptom-free infection in about one-quarter of the world's population, approximately 2 billion people. In 2024 alone, WHO reported that more than 10 million people worldwide developed active TB disease, with 1.2 million deaths recorded. This makes TB the leading cause of death from a single infectious disease.
In recent years, WHO has called for therapeutic vaccines that can be used alongside drug therapies to shorten TB treatment regimens and improve outcomes, particularly because long multidrug courses are difficult to complete, and drug-resistant TB strains continue to emerge. The vaccine described in the new Johns Hopkins study shows promise for meeting that need.
"Administered together with first-line TB drug therapy, our intranasal DNA fusion vaccine helped infected mice clear the disease bacteria faster, reduced lung inflammation and prevented relapse after treatment ended," says study lead author Styliani Karanika, M.D., a faculty member of the Johns Hopkins Center for Tuberculosis Research and assistant professor of medicine at the Johns Hopkins University School of Medicine. "The vaccine also helped the powerful TB drug combination of bedaquiline, pretomanid and linezolid work better, suggesting it could be used with treatments against drug-resistant TB to help the body fight the disease, even hard-to-treat cases."
The new Johns Hopkins vaccine, says Karanika, fuses two genes, relMtb and Mip3α, and is given through the nose to take advantage of three beneficial biological activities.
"First, TB bacteria possess a gene, relMtb, that produces a protein, RelMtb, to help the microbes survive hostile conditions such as antibiotic exposure, low oxygen and nutrient limitation by entering a drug-tolerant persistent state," she says. "Fusing relMtb with the Mip3α gene produces a signal that attracts immature dendritic cells — key cells that pick up TB proteins and 'present' them to T cells, the immune cells that help coordinate a targeted attack on the TB bacteria."
"Finally, intranasal delivery focuses vaccination on the respiratory mucosa in the lungs where TB infection occurs, helping generate long-lasting localized T-cell immunity in the airways and lungs, along with systemic immune responses," says Karanika.
By combining these strategies, the investigators aimed to strengthen immune activity directly in the respiratory tract. In the mouse studies, this approach increased dendritic cell recruitment and activation, improved how closely dendritic cells and T cells were organized in the lungs, and generated durable, antigen‑stimulated T-cell responses — both locally and systemically — from two types of T cells, CD4 (also known as helper T cells) and CD8 (also known as killer T‑cells).
In rhesus macaques, the researchers found that their nose-delivered DNA vaccine prompted measurable TB‑focused immune responses in blood and in the airways similar to what led to lower bacterial counts in the lungs of mice they studied. These responses persisted for at least six months, suggesting durability for the vaccine's action. However, says Karanika, this primate work only measured immune activation and not response to a TB challenge.
She says more studies are needed before any human clinical trials can be approved.
"These nonhuman primate data are encouraging because they show that the Mip3α/relMtb vaccine can generate durable, antigen-stimulated immune responses in an animal model whose immune system more closely resembles that of humans," says Karanika. "That gives us an important translational bridge between the mouse efficacy studies and the additional preclinical work needed before human trials."
The authors say their findings support a broader strategy of targeting TB persisters with immunotherapy, rather than relying solely on antibiotics to eliminate actively replicating bacteria. Because DNA vaccines are relatively stable and can be manufactured efficiently, they may offer practical advantages if this approach ultimately proves effective in humans.
Along with Karanika, the Johns Hopkins research team included Tianyin Wang, Addis Yilma, Jennie Ruelas Castillo, James Gordy, Hannah Bailey, Darla Quijada, Kaitlyn Fessler, Rokeya Tasneen, Elisa M. Rouse Salcido, Farah Shamma, Harley Harris, Fengyixin Chen, Rowan Bates, Heemee Ton, Jacob Meza, Yangchen Li, Alannah Taylor, Jean Zheng, Jiaqi Zhang, Theodoros Karantanos, Amanda Maxwell, Eric Nuermberger, J. David Peske, Richard Markham and Petros Karakousis.
Federal funding for the study came from National Institutes of Health grants R01AI148710, K24AI143447, P30AI18436, K08AI174959 and P30CA006973.
Additional funding was provided by a Gilead HIV Research Scholar Award, a Johns Hopkins University Tuberculosis Research Advancement Center Developmental Award, a Center for HIV/AIDS Developmental Award from the Johns Hopkins University Center for AIDS Research, a Willowcraft Foundation Award, a Johns Hopkins University Clinician Scientist Award and the Potts Memorial Foundation.
Karanika, Gordy, Markham and Karakousis are inventors on patent PCT/US2023/065584 for the Mip3α/relMtb vaccine. None of the authors have any conflict-of-interest disclosures to report.
