Bacterial aggregates of Neisseria meningitidis flow inside blood vessels like a honey-like viscous liquid
Daria Bonazzi (Institut Pasteur, Paris)
During human meningococcal infections, bacteria accumulate and finally fill up blood vessels, causing severe diseases such as septicaemia and meningitis. However, the mechanisms governing formation of bacterial aggregates and their impact on infection remained elusive. In this multidisciplinary work we unravel that aggregates of Neisseria meningitidis behave as a viscous liquid similar to honey. This is due to type-IV pili, long adhesive filaments which are constantly extending and retracting at the bacterial surface. By these means, bacteria can find each other and transiently come into contact. Aggregation is therefore based on an intermittent process of attraction between bacteria, and gives rise to a new type of active material. Importantly, the unique physical properties of meningococcal aggregates allow them to gradually adapt to the complex geometry of the vascular network. As a consequence, these physical properties are essential for the progression of infection.