Bacteriophage Makes Harmless Neisseria Bacteria Deadly

Bacterial meningitis is brought about when a virus invades otherwise-harmless Neisseria meningitidis bacteria, French researchers believe. Their research indicates that infection of the Neisseria bacteria by a bacteriophage turns the bacteria "hyperinvasive" and pathogenic, leading to brain infections when the bacteria cross the host's blood-brain barrier.

More general info at Reuters; hard-core details at JEM.