Researchers at Johns Hopkins Medicine and the Johns Hopkins Bloomberg School of Public Health have developed an experimental therapeutic DNA vaccine for tuberculosis (TB) that is delivered through the nose. The vaccine is designed to help the immune system identify and attack drug-tolerant TB bacteria known as “persisters,” which can survive lengthy antibiotic treatment and later trigger a relapse of the disease.
The findings were published in the Journal of Clinical Investigation.
Tuberculosis has afflicted humans for at least 6,000 years and remains one of the world’s deadliest infectious diseases. According to the World Health Organization (WHO), roughly one-quarter of the global population, about 2 billion people, carry latent TB infections without symptoms. In 2024, more than 10 million people developed active TB, and 1.2 million died from the disease, making it the leading cause of death from a single infectious pathogen.
New Approaches Needed for Tuberculosis Treatment
WHO has emphasized the need for therapeutic vaccines that can complement existing drug treatments. Such vaccines could potentially shorten lengthy treatment regimens and improve outcomes, especially as multidrug therapies can be difficult for patients to complete and drug-resistant forms of TB continue to spread.
Results from the new Johns Hopkins study suggest this vaccine approach could help address those challenges.
“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.”
How the Experimental TB Vaccine Works
According to Karanika, the vaccine combines two genes, relMtb and Mip3α, and is administered through the nose to take advantage of several biological mechanisms that may strengthen immunity against TB.
“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.”
The vaccine is also designed to focus immune activity where TB infections begin.
“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.
Strong Immune Responses in Animal Studies
By combining these mechanisms, the researchers sought to strengthen immune defenses directly within the respiratory tract. In mouse experiments, the vaccine increased recruitment and activation of dendritic cells, improved the organization of dendritic cells and T cells within lung tissue, and generated durable, antigen-stimulated T-cell responses — both locally and systemically — from CD4 (also known as helper T cells) and CD8 (also known as killer T-cells).
The team also evaluated the vaccine in rhesus macaques. The nose-delivered DNA vaccine generated measurable TB-specific immune responses in both the bloodstream and airways. These responses resembled those associated with reduced bacterial levels in the lungs of vaccinated mice.
Researchers observed that the immune responses lasted for at least six months, suggesting the vaccine may provide durable protection. However, Karanika notes that the primate study assessed immune activation only and did not test how the animals responded to an actual TB infection.
She says additional research will be required before the vaccine can advance to human clinical trials.
“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.”
Targeting TB Persisters With Immunotherapy
The researchers believe their results support a broader treatment strategy that focuses on eliminating TB persisters through immunotherapy rather than relying exclusively on antibiotics to kill actively growing bacteria.
Because DNA vaccines are generally stable and can be produced efficiently, the approach could offer practical advantages if future studies demonstrate similar benefits 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 support came from 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. The authors reported no conflicts of interest.
