Bordetella pertussis, the causative agent of whooping cough, is an extracellular, strictly human pathogen. However, it has been shown that B. pertussis cells can escape phagocytic killing and survive in macrophages upon internalization. Our time-resolved RNA-seq data suggest that B. pertussis efficiently adapts to the intramacrophage environment and responds to host bactericidal activities. We show that this adaptive response is multifaceted and, surprisingly, related to the BvgAS two-component system, a master regulator of virulence. Our results show that the expression of this regulatory circuit is downregulated upon internalization. Moreover, we demonstrate that the switch to the avirulent Bvg- phase augments a very complex process based on the adjustment of central and energy metabolism, cell wall reinforcement, maintenance of appropriate redox and metal homeostasis, and repair of damaged macromolecules. Nevertheless, not all observed effects could be simply attributed to the transition to Bvg- phase, suggesting that additional regulators are involved in the adaptation to the intramacrophage environment. Interestingly, a large number of genes required for the metabolism of sulphur were strongly modulated within macrophages. In particular, the mutant lacking two genes encoding cysteine dioxygenases displayed strongly attenuated cytotoxicity toward THP-1 cells. Collectively, our results suggest that intracellular B. pertussis cells have adopted the Bvg- mode to acclimate to the intramacrophage environment and respond to antimicrobial activities elicited by THP-1 cells. Therefore, we hypothesize that the avirulent phase represents an authentic phenotype of internalized B. pertussis cells.

• Klíčová slova
• Bordetella pertussis, BvgAS, adaptation to stress, avirulent phase, cysteine toxicity, intramacrophage environment,
• MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• Bordetella pertussis * metabolismus   MeSH
• fenotyp MeSH
• lidé MeSH
• makrofágy metabolismus   MeSH
• pertuse * MeSH
• regulace genové exprese u bakterií MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny MeSH

The ability of bacterial pathogens to acquire essential micronutrients is critical for their survival in the host environment. Manganese plays a complex role in the virulence of a variety of pathogens due to its function as an antioxidant and enzymatic cofactor. Therefore, host cells deprive pathogens of manganese to prevent or attenuate infection. Here, we show that evolution of the human-restricted pathogen Bordetella pertussis has selected for an inhibitory duplication within a manganese exporter of the calcium:cation antiporter superfamily. Intriguingly, upon exposure to toxic levels of manganese, the nonfunctional exporter becomes operative in resister cells due to a unique reverse adaptation mechanism. However, compared with wild-type (wt) cells, the resisters carrying a functional copy of the exporter displayed strongly reduced intracellular levels of manganese and impaired growth under oxidative stress. Apparently, inactivation of the manganese exporter and the resulting accumulation of manganese in the cytosol benefited the pathogen by improving its survival under stress conditions. The inhibitory duplication within the exporter gene is highly conserved among B. pertussis strains, absent from all other Bordetella species and from a vast majority of organisms across all kingdoms of life. Therefore, we conclude that inactivation of the exporter gene represents an exceptional example of a flexible genome decay strategy employed by a human pathogen to adapt to its exclusive host. IMPORTANCE Bordetella pertussis, a respiratory pathogen restricted to humans, continuously adapts its genome to its exclusive host. We show that speciation of this reemerging pathogen was accompanied by loss of function of the manganese exporter. Intriguingly, the functionality of the exporter can be restored in the presence of toxic levels of manganese by a unique genetic modification. However, compared with the wt strain, the strain carrying the functional exporter failed to resist the oxidative stress in vitro. Thus, our data demonstrate that inactivation of the exporter resulting in manganese accumulation assists B. pertussis in adaptation to oxidative stress. We conclude that this sophisticated process of reverse adaptation enables B. pertussis to adjust to rapidly changing environments by facilitating its resistance to both manganese toxicity and manganese scarcity.

• Klíčová slova
• Bordetella, Bordetella pertussis, genome decay, manganese, oxidative stress, pathogen adaptation,
• MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• Bordetella pertussis účinky léků   genetika   patogenita   MeSH
• faktory virulence genetika   MeSH
• lidé MeSH
• mangan toxicita   MeSH
• oxidační stres MeSH
• pertuse prevence a kontrola   MeSH
• regulace genové exprese u bakterií účinky léků   MeSH
• virulence účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• faktory virulence MeSH
• mangan MeSH