The Bordetella species, B. pertussis, B. parapertussis, and B. bronchiseptica, the so-called classical bordetellae cause respiratory infections in diverse mammals.

We have shown recently that the type III secretion system effector BteA of the exclusively human-adapted pathogen B. pertussis exhibits a significantly reduced specific cytotoxic activity compared to its homolog of the animal pathogen B. bronchiseptica. We further showed that this difference is due to the insertion of a single alanine residue at position 503 of the BteA of B. pertussis. Moreover, we revealed that this functional adaptation reduced the capacity of B. pertussis to suppress host inflammatory response, which might contribute to an acute course human pertussis.