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Bordetella bronchiseptica responses to physiological reactive nitrogen and oxygen stresses

Omsland, Anders, Miranda, Katrina M., Friedman, Richard L., Boitano, Scott
FEMS microbiology letters 2008 v.284 no.1 pp. 92-101
Bordetella bronchiseptica, antibacterial properties, dose response, hydrogen peroxide, immune response, innate immunity, mammals, mucosa, nitric oxide, nitrogen, oxygen, pathogens, respiratory system
Bordetella bronchiseptica can establish prolonged airway infection consistent with a highly developed ability to evade mammalian host immune responses. Upon initial interaction with the host upper respiratory tract mucosa, B. bronchiseptica are subjected to antimicrobial reactive nitrogen species (RNS) and reactive oxygen species (ROS), effector molecules of the innate immune system. However, the responses of B. bronchiseptica to redox species at physiologically relevant concentrations (nM-μM) have not been investigated. Using predicted physiological concentrations of nitric oxide (NO), superoxide and hydrogen peroxide (H₂O₂) on low numbers of CFU of B. bronchiseptica, all redox active species displayed dose-dependent antimicrobial activity. Susceptibility to individual redox active species was significantly increased upon introduction of a second species at subantimicrobial concentrations. An increased bacteriostatic activity of NO was observed relative to H₂O₂. The understanding of Bordetella responses to physiologically relevant levels of exogenous RNS and ROS will aid in defining the role of endogenous production of these molecules in host innate immunity against Bordetella and other respiratory pathogens.