Meningitis causes inflammation in the fluid and membranes around the spinal cord and brain. The condition can take hold in the body via viral, parasitic, fungal, and bacterial infections. Those caused by bacteria are the most dangerous because they can enter the bloodstream, leading to severe complications resulting in a life-threatening condition within hours if left untreated.
The bacteria Neisseria meningitidis is one of the leading causes of bacterial meningitis. It induces infection in the upper respiratory tract; from there, it can enter the bloodstream to cause meningococcal meningitis. The body has a defense against this: the friendly bacteria Neisseria lactamica naturally prevents N. meningitidis from taking hold. N. lactamica can be found in the nose of some young people and infants.
University of Southampton scientists have been testing ways to leverage this natural barrier against infection. Their most recent work is a world-first trial demonstrating the potential of a new meningococcal meningitis vaccine that a medical professional can deliver via nose drops. The results provided long-lasting protection, and the method may be replicable to address other infections that work via similar mechanisms.
To make the vaccine extra-effective, the scientists engineered N. lactamica to have similar properties to N. meningitidis. The thing that makes N. meningitidis so threatening is its sticky surface protein used to fasten onto the cells lining the inner nose. So, the team copied the gene that codes for this protein into N. lactamica’s DNA, thus giving it the same capability.
A group of healthy subjects took the vaccine, and all carried the bacteria asymptomatically for at least 28 days; 86% of the participants still carried it after 90 days. Having the engineered N. lactamica stuck in their nose generated a solid natural immune response against N. meningitidis with no transmission to close contacts of the subjects and no adverse symptoms.
Professor Robert Read, who led the research, said:
This work has shown that it is possible to protect people from severe diseases by using nose drops containing genetically modified friendly bacteria. 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 team envisions the technology acting as a platform for tackling diseases that enter the body through the upper respiratory tract. The idea is simple but effective; adapt an engineered bacteria to carry an antigen that counters the infection and drop it into the nose.
A couple of other recent non-injection types of vaccines include the edible cholera vaccine made of rice and the dengue virus vaccine patch.
