Bordetella pertussis Can Be Motile and Express Flagellum-Like Structures.

encodes and expresses a flagellar apparatus. In contrast, , the causative agent of whooping cough, has historically been described as a nonmotile and nonflagellated organism. The previous statements that was a nonmotile organism were consistent with a stop codon located in the flagellar biosynthesis gene, , discovered when the Tohama I genome was sequenced and analyzed by Parkhill et al. in 2003 (J. Parkhill, M. Sebaihia, A. Preston, L. D. Murphy, et al., Nat Genet, 35:32-40, 2003, https://doi.org/10.1038/ng1227). The stop codon has subsequently been found in all annotated genomes. Parkhill et al. also showed, however, that contains all genetic material required for flagellar synthesis and function. We and others have determined by various transcriptomic analyses that these flagellar genes are differentially regulated under a variety of growth conditions. In light of these data, we tested for motility and found that both laboratory-adapted strains and clinical isolates can be motile. Upon isolation of motile , we discovered flagellum-like structures on the surface of the bacteria. motility appears to occur primarily in the Bvg(-) phase, consistent with regulation present in Motility can also be induced by the presence of fetal bovine serum. These observations demonstrate that can express flagellum-like structures, and although it remains to be determined if expresses flagella during infection or if motility and/or flagella play roles during the cycle of infection and transmission, it is clear that these data warrant further investigation. This report provides evidence for motility and expression of flagella by , a bacterium that has been reported as nonmotile since it was first isolated and studied. As with , cells can express and assemble a flagellum-like structure on their surface, which in other organisms has been implicated in several important processes that occur The discovery that is motile raises many questions, including those regarding the mechanisms of regulation for flagellar gene and protein expression and, importantly, the role of flagella during infection. This novel observation provides a foundation for further study of flagella and motility in the contexts of infection and transmission.