People with “friendly” bacteria in the nose drops protected from meningitis

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Gram stain of meningococci from a culture showing Gram-negative (pink) bacteria, often in pairs. Credit: public domain

Led by Professor Robert Read and Dr Jay Laver of the NIHR Southampton Biomedical Research Center and the University of Southampton, the new research in immunology is the first of its kind.

Together they inserted a gene into a harmless type of , which allows it to stay in the nose and elicit an immune response. They then introduced these bacteria into the noses of healthy volunteers using nasal drops.

The results, published in the journal Scientific translational medicine, showed a strong immune response against meningitis-causing bacteria. These data also show lasting protection.

Meningitis occurs in people of all age groups, but mainly affects infants, young children, and the elderly. Meningococcal meningitis is a bacterial form of the disease, which causes 1,500 cases a year in the UK. It can lead to death in just four hours after symptoms begin.

About 10% of adults carry N. meningitidis on the back of their nose and throat with no signs or symptoms. However, in some people it can invade the bloodstream. This can lead to life-threatening situations, such as meningitis and blood poisoning (sepsis).

The “friendly” bacterium Neisseria lactamica (N. lactamica) also lives in some people’s noses naturally. Occupying the nose, it protects against a severe type of meningitis. He does so by denying a step to his cousin Neisseria meningitidis (N. meningitidis).

The new data is based on the previous work of the team with the aim of exploiting this natural phenomenon. This study showed that N. lactamica nasal drops prevented N. meningitidis from settling in 60% of participants.

For these people, N. lactamica had shut down her deadly cousin. This spurred work to make N. lactamica even more effective in displacing N. meningitidis.

The team did so by handing him one of the key weapons of N. meningitidis, a “sticky” surface protein that catches the cells lining the nose. By inserting a copy of the gene for this protein into N. lactamica DNA, it could also displace it, equalizing the playing field.

In addition to inducing a stronger immune response, these modified bacteria remained longer. Present for at least 28 days, with the majority of participants (86%) wearing it at 90 days, causing no adverse symptoms.

The results of the study, funded by the Medical Research Council, are promising for this new way to prevent life-threatening infections without drugs. It is an approach that could be critical 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 has identified the potential of our recombinant N. lactamica technology to protect people from meningococcal disease, the technology of underlying platform has wider applications.

“Theoretically it is possible to express any antigen in our bacteria, which means we can potentially adapt them to fight a multitude of infections that enter the body through the upper respiratory tract. In addition to the delivery of vaccine antigens, advances in synthetic biology they also mean we could use genetically modified bacteria to make and deliver therapeutic molecules in the near future. “

Professor Read, director of the NIHR Southampton Biomedical Research Center, said: “This work has shown that it is possible to protect people from serious diseases by using drops containing genetically modified friendly bacteria. We believe it will probably be a popular and successful way to protect people from a number of diseases in the future. ”


Doctors are developing a pioneering nasal drop to help fight meningitis


More information:
Jay R. Laver et al, A recombinant commensal bacterium elicits specific immune responses of heterologous antigens during pharyngeal transport, Scientific translational medicine (2021). DOI: 10.1126 / scitranslmed.abe8573

Citation: People with “friendly” bacteria in meningitis-protected nasal drops (2021, July 12) recovered on July 13, 2021 at https://medicalxpress.com/news/2021-07-people-friendly-bacteria- nose-meningitis.html

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