Submitted to: Anaerobe
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2004
Publication Date: 8/1/2004
Citation: Zuerner, R.L., Stanton, T.B., Minion, C., Li, C., Charon, N., Trott, D.J., Hampson, D. 2004. Genetic variation in Brachyspira: Chromosomal Rearrangements and Sequence Drift Distinguish B. pilosicoli from B. hyodysenteriae. Anaerobe 10 (2004): 229-237. Interpretive Summary: Brachyspira cause intestinal infections in livestock, leading to economic losses in the poultry and pork industries. Little is known about how these bacteria cause infections. To establish a basis to analyze two important species of Brachyspira we constructed maps of their chromosomes, and localized several genes that influence the ability to infect animals. Characterization of one region in particular led to the discovery of a toxin gene in both species. These data will lead to the analysis of this gene in disease.
Technical Abstract: Brachyspira pilosicoli causes intestinal spirochetosis in mammals and birds. Little is known about the size, organization, or content of the B. pilosicoli genome. In this study, we constructed a combined physical and genetic map of the B. pilosicoli genome and compared it to B. hyodysenteriae. The B. pilosicoli genome is smaller than the B. hyodysenteriae genome, and genetic organization in these bacteria is different. Differences in the size and organization of these two genomes may influence the ability of these bacteria to infect different hosts and cause disease. Therefore, we examined the B. pilosicoli genome for the presence of various genes thought to contribute to B. hyodysenteriae virulence. One example of this analysis is the bit locus, a cluster of iron regulated B. hyodysenteriae genes that were not detected in B. pilosicoli. Hybridization analysis was also used to localize putative hemolysin genes tlyA, tlyB, tlyC, and hlyA in B. pilosicoli. In both B. hyodysenteriae and B. pilosicoli, hlyA is flanked on both sides by genes encoding proteins associated with ACP processing, fabG, an ACP-reductase, and fabF, an ACP-synthase. Substantial sequence variation flanking hlyA may alter the expression of this gene in B. pilosicoli, thereby limiting the production of hemolytic activity.