Through a world-first trial, scientists in the UK have demonstrated the potential of a new vaccine to treat a life-threatening form of meningitis, and it can be delivered via nose drops. The researchers have developed a way of preventing meningococcal meningitis by borrowing a weapon used by the bacteria that causes it, resulting in long-lasting protection that might be replicated to address other infections that work via similar mechanisms.
As a condition that causes inflammation in the fluid and membranes around the brain and spinal cord, meningitis can take hold in the body through viral, fungal and parasitic infections, though those caused by bacteria are particularly dangerous. This is because bacterial meningitis has the capacity to enter the blood stream, resulting in serious complications and with the potential to become a life-threatening condition in hours if left untreated.
One of the leading causes of bacterial meningitis is Neisseria meningitidis, bacteria that causes an infection in the upper respiratory tract and can enter the bloodstream to cause meningococcal meningitis. The body has a defense against this in the form of the friendly bacteria Neisseria lactamica, which can be found in the nose of some infants and young people and naturally prevents N. meningitidis from taking hold.
Previously, scientists at the University of Southampton had looked to leverage this natural barrier against infection by administering N. lactamica to subjects via nose drops, and found that it prevented N. meningitidis from settling in 60 percent of participants. The same researchers have now built on these promising results to make N. lactamica an even more effective safeguard against N. meningitidis.
One of the things that makes N. meningitidis such a potent threat is a sticky surface protein that it uses to grip onto the cells lining the inside of the nose. The scientists were able to copy the gene that codes for this protein into the DNA of N. lactamica, in effect giving it the same capability.
This engineered N. lactamica was administered to a group of healthy subjects, who carried the bacteria asymptomatically for at least 28 days, with the majority, 86 percent, still carrying it at 90 days. This generated a strong immune response across this period to protect against N. meningitidis and led to no adverse symptoms or transmission to close contacts of the subjects.
The team concludes that the engineered bacteria could therefore prove a safe and effective vaccine vector in humans, and perhaps much more than that. The scientists hope the technology can act as a platform for tackling other diseases that enter the body via the upper respiratory tract, by simply adapting the engineered bacteria to carry antigens that counter other infections.
“This work has shown that it is possible to protect people from severe diseases by using nose drops containing genetically modified friendly bacteria," says Professor Robert Read, who led the research. "We think this is likely to be a very successful and popular way of protecting people against a range of diseases in the future.”
The research was published in the journal Science Translational Medicine.
Source: University of Southampton
