In a recent study, researchers from the University of Southampton in the UK inserted a gene into a harmless bacteria that allowed it to stay in the nose for a long time and trigger an immune response. They then introduced the bacteria into the noses of healthy volunteers through nasal drops. The results show that this approach can produce a strong immune response against the bacterium that causes meningitis, Neisseria meningitidis, and provide lasting protection. The results were published in the July 7, 2021 in the Science Translational Medicine journal entitled “A recombinant commensal bacteria elicits heterologous antigen-specific immune responses during pharyngeal carriage”. The correspondent is Dr. Jay Laver from the University of Southampton.
Meningitis occurs in all ages, but mainly affects infants, young children, and the elderly, which is a bacterial disease, with 1,500 cases a year in the UK. It can lead to death within four hours of the onset of symptoms. About 10% of adults carry Neisseria meningitidis on the back of their noses and throats without any signs or symptoms. However, in some people, it can invade the blood to cause life-threatening symptoms, including meningitis and blood poisoning (septicemia).
A friendly bacterium called Neisseria lactamica lives naturally in some people’s noses. It can protect people from severe types of meningitis.
The new data are based on previous research by the Laver team, which took advantage of this natural phenomenon, showing that lactose Neisseria nasal drops prevented Neisseria meningitidis from colonizing in 60% of participants. For these people, Neisseria lactamica has shut out this deadly bacterium. This finding has prompted research to make Neisseria lactamica more effective in replacing Neisseria meningitidis.
The researchers did this by supplying Neisseria meningitidis with one of its key weapons-a “sticky” surface protein that grabs cells in the nasal wall, known as Neisseria Adhesin A (NadA). By inserting a copy of the gene that encodes the NadA into the DNA of Neisseria lactamica, the role of Neisseria lactamica can be replaced to level the competition.
In addition to inducing a stronger immune response, these genetically modified bacteria stay longer. It existed for at least 28 days, and most participants (86%) still carried it for 90 days, which did not cause any adverse effects. The results suggest that this new method of preventing life-threatening infections without the use of drugs is promising, which may be a crucial approach in the face of growing antimicrobial resistance.
Dr. Jay Laver, a senior researcher in Molecular Microbiology at the University of Southampton, commented, “although this study confirms the potential of our recombinant Neisseria lactamica technology in protecting people from meningococcal disease, it has a wider range of applications. In theory, it is possible to express any antigen in our bacteria, which means that it is possible to genetically modify them to combat multiple infections that invade the body through the upper respiratory tract. In addition to delivering vaccine antigens, advances in synthetic biology mean that we may also use genetically modified bacteria to make and deliver therapeutic molecules in the near future.”