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‘Good’ bacteria could offer protection in new meningitis vaccine

Southampton researchers are using a protective bacteria that naturally lives in our nose to develop a new meningitis vaccine.

Dr Adam Dale from the NIHR Southampton Biomedical Research Centre’s Microbiology, Immunology and Infection theme will lead a new study.

Preventing silent carriers

Meningitis is an infection of the protective membranes that surround the brain and spinal cord. If not treated quickly, it can cause life-threatening infection and result in permanent damage to the brain or nerves.

One bacterial species that causes meningitis is Neisseria meningitidis. This commonly lives in the nose and throat without causing symptoms. It transmits from person-to-person through close contact. Infections can be life threatening in those who do not have protective immunity. This most commonly occurs in babies and young children.

There are vaccines that can be used to prevent infections caused by N. meningitidis. The most effective vaccines offer protection against both disease and silent (asymptomatic) carriage in the nose and throat. Preventing silent carriage reduces person-to-person transmission and is the basis of so-called ‘herd immunity’.

However, not all N. meningitidis vaccines protect against silent carriage. This can reduce their effectiveness and limit herd immunity. To improve this, researchers need to develop new ways of preventing the silent carriage of N. meningitidis.

‘Good’ vs ‘bad’ bacteria

People with a type of ‘good’ bacteria in their nose are known to be protected against N. meningitidis. This good bacteria, Neisseria lactamica, is a cousin of the disease-causing bacteria. It is completely harmless.

Professor Robert Read’s research group has previously shown that people deliberately infected with the good bacteria are protected from silent carriage with N. meningitidis.

In a recent study, led by Dr Dale, researchers found this may be due to generation of immune responses towards N. meningitidis triggered by the ‘good’ bacteria. In a further study, led by Dr Jay Laver, these immune responses were enhanced. The researchers did this by engineering the good bacteria to harmlessly make components of N. meningitidis that are easily recognisable by the human immune system.

In planned work, Dr Dale’s team will study the body’s responses to contact with this modified ‘good’ bacteria in more detail. He hopes to tease out exactly how people who have the good bacteria in their nose are protected.

Dr Dale, NIHR Clinical Lecturer in Infectious Diseases & Medical Microbiology at the University of Southampton, said:

“This study could give us new insights to help answer the question of exactly how Neisseria lactamica protects people.

“It could pave the way to a new vaccine that would not only protect against life-threatening infection caused by N. meningitidis, but also prevent its silent spread to babies and children.”

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