New Plague Vaccine Offers Powerful Protection across Deadly Strains

The Black Death is often seen as a relic of the past. Many believe plague no longer affects modern people or communities. But plague still causes illness and death around the world today. In July 2025, Coconino County, Arizona reported its first pneumonic plague death in 18 years.

Nearly 1000 years after the first major outbreak, a new vaccine emerged. Researchers have created an mRNA-based vaccine against Yersinia pestis. This bacterium causes both bubonic and pneumonic plague. The vaccine marks the first mRNA vaccine to target a bacterial pathogen. The research was published in Advanced Science.

The vaccine was conceived by Tel Aviv University and Israel’s Biological Research Institute. It uses lipid nanoparticles to deliver modified bacterial protein instructions. These help human cells produce plague antigens to train the immune system. Tests in animal models showed strong protection against deadly plague strains.

This breakthrough offers hope beyond plague prevention. The technology could lead to vaccines for antibiotic-resistant bacteria. These bacteria cause hard-to-treat infections and kill thousands each year. Drug-resistant infections are expected to worsen in coming decades.

How Researchers Developed a New Plague Vaccine

Researchers developed the vaccine using two mRNA constructs targeting LcrV protein. LcrV is a key factor that helps Yersinia pestis cause disease. The study tested two LcrV variants, both alone and with F1. F1 is another plague antigen that boosts immune protection.

The combined vaccine used mRNA for both LcrV and F1 antigens. This approach triggered strong immunity in mice exposed to Y. pestis. Mice were protected even after lethal bacterial challenge. The vaccine worked against multiple strains, including wild and unencapsulated types.

Protection remained strong against highly virulent plague exposures. These results show mRNA vaccines can fight bacteria, not just viruses. Lipid nanoparticles carried the mRNA into host cells for processing. Inside, cells made plague proteins that trained the immune system.

This response helped strengthen immunity before any real infection occurred. The vaccine successfully primed the body to recognize and fight plague. These findings show mRNA’s potential to combat other deadly bacteria.

How Researchers Tested the Vaccine’s Effectiveness

Researchers tested the vaccine by vaccinating mice three times, two weeks apart. They tracked antibody levels after each dose to measure immune response. After three doses, mice showed strong protection and high antibody levels. All mice that received the full vaccine survived infection.

Even two doses gave full protection in some test groups. Imaging showed unvaccinated mice had fast bacterial spread in their lungs. In contrast, vaccinated mice showed no sign of infection at all. This confirmed the vaccine blocked bacterial growth inside the body.

Next, researchers tested the vaccine against a stronger bacterial challenge. Mice were given two or three doses, then exposed to 100 times the lethal amount of Y. pestis. All mice survived after three doses, across all strains tested. After two doses, survival remained high but varied by strain.

Researchers then tested the vaccine on an unencapsulated plague strain. This version of Y. pestis does not produce the F1 capsule. That means the F1 antigen offers no protection in this case. As expected, all mice given F1 alone died after exposure.

Mice vaccinated with the bivalent vaccine showed high survival rates. Those given LcrV-only mRNA also survived at similar levels. This proves that LcrV is the key protective factor in unencapsulated strains. It plays a critical role in defending against pneumonic plague.

What Future Developments Could Stem from this New Vaccine?

The mRNA vaccine protected against multiple strains of plague bacteria. It worked against both Orientalis and Medievalis forms of Y. pestis. This shows the vaccine could help stop future outbreaks or bioterror threats. It also protected against an F1-negative strain, which lacks the capsule.

Researchers believe future vaccines could include more bacterial antigens. Adding new targets may improve protection and expand coverage. The mRNA platform supports multivalent vaccines with two or more antigens. This flexibility allows for fast updates as threats evolve.

Multivalent mRNA vaccines may reduce antibiotic use worldwide. They could help fight antimicrobial resistance by preventing bacterial infections. The platform is fast, customizable, and effective across disease types. Other mRNA studies show similar success against different bacterial pathogens.

More research is still needed before human use. Mouse data may not fully predict human immune responses. Future studies must include more models like non-human primates. Long-term immunity also needs testing to see how long protection lasts.

Rapid protection is helpful, but lasting defense is essential. Researchers say understanding vaccine durability will guide next development steps. The findings show promise, but human trials remain a critical future goal.

Conclusion

A new mRNA vaccine platform offers fast, flexible protection against plague pathogens. With further testing, it could help prevent future outbreaks and global health threats.

Have an upcoming trip? Passport Health offers a wide variety of options to help keep you safe from disease, including vaccines. Call or book online to schedule your appointment today.

Logan Hamilton is a health and wellness freelance writer for hire. He’s passionate about crafting crystal-clear, captivating, and credible content that elevates brands and establishes trust. When not writing, Logan can be found hiking, sticking his nose in bizarre books, or playing drums in a local rock band. Find him at loganjameshamilton.com.