Neisseria meningitidis undergoes PilC phase variation and PilE sequence variation during invasive disease.

Neisseria meningitidis colonizes the upper respiratory tract (URT), enters the blood stream, and reaches the cerebrospinal fluid (CSF). In the present study, we show that bacteria isolated from the URT adhere better to human epithelial cells, compared with bacteria from blood or CSF, which suggests that important changes of virulence-associated proteins take place during bacterial dissemination. Phase variation in the pilus adhesin PilC and sequence variation in the pilus subunit PilE occurred among strains from 1 patient. Changes were not found in the invasion-associated opacity proteins or in lipooligosaccharides. PilC was frequently expressed in serogroup B strains and in URT strains but was often switched off in other serogroups and in CSF strains. Strains lacking PilC showed impaired adhesion to epithelial cells. These data argue that N. meningitidis undergoes PilC phase variation and PilE sequence variation during invasive disease.