Functional Bacterial Amyloid is Present in Bordetella Species

Amyloid, any protein defined by a fibrillar cross β-sheet quaternary structure, is associated with neurodegenerative diseases, such as Alzheimer’s and Parkinson’s disease and is a functional component in humans, invertebrates, fungi, and bacteria. Many species of both Gram-positive and Gram-negative bacteria express amyloid either on the cell surface or inside the cell envelope. Extracellular functional bacterial amyloid contributes to biofilm formation, adhesion, and host cell invasion. Bordetella pertussis, the causative agent of whooping cough in humans, and Bordetella bronchiseptica, the causative agent of respiratory disease in four-legged mammals, form biofilms but have not been previously addressed to contain functional bacterial amyloid. Through the use of Congo red, an amyloid-specific dye, several strains of B bronchiseptica and B.pertussis were tested. We found the strain RB50, a wild type of B.bronchiseptica, as well as mutants RB53 and RB53i, make amyloid on the extracellular matrix. Both species of the Bordetella genus have virulence factors regulated by a two component system known as bvgAS. In efforts to identify whether or not the amyloid is also regulated by bvgAS modulation was implemented. Modulation included variance in temperature and the addition of compounds known to suppress bvgAS to the plates containing Congo red.  From modulation we found the amyloid positive strains to be bvg regulated. The discovery of extracellular amyloid on Bordetella bronchiseptica provides a gateway for the development of more effective therapeutics against pathogenesis as we examine amyloid and its relationship to bvgAS.