Study of French B.pertussis isolates non producing a vaccine antigen. PRN- and FHA- french B.pertussis isolates

The introduction of vaccination against Pertussis applied a selective pressure to the circulating B. pertussis populations. They first had to evolve in response to whole cell vaccines (wP) vaccines world-wide and now to acellulare vaccines (aP) in high income countries only. Changes in B. pertussis populations under vaccine pressure were already described during the wP era. Allelic variations were observed in genetic regions of antigenic relevance. However, these changes did not impact the effectiveness of efficacious wP vaccines. Use of aP vaccines against Pertussis led to an increased circulation of clinical isolates not producing PRN in different countries immunizing with aP vaccines with a high incidence in some of them. Some rare isolates no more producing FHA were also reported in some countries. In this project, we analyzed PRN-deficient and FHA-deficient B. pertussis isolates in order to better understand the causes and the consequences of their presence at such a high level in some aP vaccinated areas. We selected recent French clinical isolates (producing or not PRN and/or FHA) to determine their genome characteristics. We also analysed their virulence factor gene transcription profile and finally evaluated their invasive phenotype in a Human Tracheal Epithelial (HTE) cellular model of infection.