New mRNA Vaccine Against World’s Biggest Infectious Killer Shows Promise

The only vaccine we have for TB right now is the BCG (Bacillus Calmette-Guérin). If, like many people, you got a dose of this at school, you’ll most likely still have the scar to show for it. It’s over a century old, and although it is effective – and may even have other medical applications that are still being explored – the level of protection it offers against TB can be variable. 

The success of the Nobel Prize-winning mRNA technology that brought us COVID-19 vaccines led researchers to wonder whether that same principle might not also be applicable to the next generation of TB vaccines. But TB is caused by bacteria, not a virus like SARS-CoV-2, and it was unclear whether mRNA could provide lasting protection.

Now, new research from Australian scientists is demonstrating that it can. 

“The success of mRNA vaccines in the COVID-19 pandemic underscored their ability to generate strong immune responses. Our study provides the evidence that this platform can be harnessed for TB, potentially improving protection and durability of immunity in a way that traditional vaccines cannot,” said co-author Professor Colin Pouton of Monash University in a statement. 

The team’s liquid nanoparticle mRNA vaccine is called mRNA^CV2. It encodes a protein from the bacterium Mycobacterium tuberculosis – by far the most common cause of the disease in humans – called CysVac2, which the team has previously demonstrated elicits an immune response in mice when included in immunizations. 

For their latest study, they tested their mRNA vaccine preparation in mice. It triggered a strong immune response, with high levels of both specific T cells and antibodies. When vaccinated mice were infected with M. tuberculosis five weeks later, their immune systems were able to strongly reduce the bacterial load in their lungs when compared with control animals. 

An additional finding was that in mice that had previously received the BCG shot, the new mRNA vaccine worked well as a booster, significantly improving long-term protection. 

“Our findings demonstrate that an mRNA vaccine can induce potent, pathogen-specific immune responses that target TB, a disease that has long evaded effective vaccine development. This represents a major advance in TB vaccine research and provides a strong rationale for further clinical development,” commented senior author Professor Jamie Triccas from the Sydney Infectious Diseases Institute. 

These are only preclinical studies, and this particular vaccine is also not the only mRNA TB vaccine under investigation – but when facing a disease that kills over a million people annually, you can never have too many preventative options. The goal for this team, Professor Triccas explained, is to further refine their formula through additional animal trials, with the hope of moving to human trials soon. 

mRNA vaccines have faced opposition from some quarters, often based on fundamental misunderstandings of how the technology works. With mRNA-based medicines and vaccines being explored for many other diseases, including various cancers, this study helps demonstrate their incredible potential.

“mRNA vaccines offer a scalable, cost-effective, and adaptable platform that can be rapidly deployed against infectious diseases,” said co-lead author Dr Claudio Counoupas from the Centenary Institute’s Centre for Infection & Immunity. “This study is an important step in demonstrating that mRNA technology is not just for COVID-19 but could be a game-changer for bacterial diseases like TB.”

The study is published in the journal eBioMedicine.