[S11-5] Bordetella toxins: adenylyl cyclase toxin, dermonecrotic toxin, pertussis toxin, and one more thing
Bordetella pertussis (Bp), B. bronchiseptica (Bb), and B. parapertussis (Bpp), which are collectively called “classical Bordetella,” are respiratory pathogens for mammals and produce various toxins such as adenylate cyclase toxin (ACT), dermonecrotic toxin (DNT), and pertussis toxin (PT). ACT and DNT are shared by these three species, and PT is specific to Bp. The molecular actions of these toxins have been extensively studied; however, their roles in the pathogenesis of each Bordetella-induced disease remain elusive. In this talk, I will introduce our recent results correlating the function of the toxins to the pathogenesis of the diseases as follows. ACT and DNT had been believed to be functionally identical among classical Bordetella and, therefore, the role of each toxin in the respiratory diseases was also presumed to be the same; however, our results demonstrate that the role of each toxin in Bp infection and Bb infection is different. It had long been argued whether PT is a causative agent for paroxysmal coughing in Bp infection. Recently, we showed that PT does not cause coughing by itself, but only by cooperative action with other virulence factors. Bb and Bpp, which also cause coughing in host animals, do not produce PT. We demonstrate that they produce a novel toxin that functions in place of PT to cause coughing.