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United States Department of Agriculture

Agricultural Research Service

Research Project: COUNTERMEASURES TO PREVENT THE PORCINE RESPIRATORY DISEASE COMPLEX (PRDC) Title: Virulence and Genome Evolution of Bordetella bronchiseptica

Authors
item Buboltz, Anne -
item Zhang, Xuqing -
item NICHOLSON, TRACY
item Sun, Yazhou -
item Zhang, F -
item Qi, Ji -
item Weyrich, Laura -
item Harvill, Eric -
item Schuster, Stephan -

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 7, 2009
Publication Date: N/A

Technical Abstract: The genetic changes that cause some isolates to be more pathogenic than others are generally not well understood. Bordetella bronchiseptica is a prime model to study the underlying factor(s) that cause some strains to be more pathogenic than others, as strains of this clonal species cause different severities of respiratory disease. Using a combination of a murine model of infection, transcriptomics, functional and mutational analyses, we previously determined that the type III secretion system (TTSS) was partially responsible for causing the increased virulence of B. bronchiseptica strain 1289, which was isolated from a host with B. bronchiseptica-induced disease. Additionally, these studies showed that another, unidentified factor was also responsible for the increased virulence strain 1289, as well as other strains in its lineage. Since other virulence factors were similarly expressed and genetic differences were not detected via comparative microarray analyses between an avirulent strain and this hypervirulent strain, we resequenced strain 1289 to identify the novel genetic factors that may contribute to this strain's increased virulence, as well as to gain a more precise understanding of B. bronchiseptica genome evolution. We utilized optical mapping to aid our bacterial genome sequence assembly and finishing steps, a tool that allowed us to rapidly disentangle contig misassembilies and identify differences in the genomic structure between our reference sequence (strain RB50) and strain 1289. More specifically, we identified five misassembles, two of which appeared to be caused by a 1.5MB genome inversion . This result was confirmed by completing an optical map of the reference genome, strain RB50, which showed that the genetic structure of this strain aligns with the published genome sequence . As far as we're aware, this is the largest single microbial genome inversion observed to date, and suggests that microbial inversions may be much larger than previously realized.

Last Modified: 9/10/2014