title: Comparative genomic analysis of Tropheryma whipplei strains reveals that diversity among clinical isolates is mainly related to the WiSP proteins.
abstract: BACKGROUND
  The aim of this study was to analyze the genomic diversity of several Tropheryma whipplei strains by microarray-based comparative genomic hybridization. Fifteen clinical isolates originating from biopsy samples recovered from different countries were compared with the T. whipplei Twist strain. For each isolate, the genes were defined as either present or absent/divergent using the GACK analysis software. Genomic changes were then further characterized by PCR and sequencing.
  
  
  RESULTS
  The results revealed a limited genetic variation among the T. whipplei isolates, with at most 2.24% of the probes exhibiting differential hybridization against the Twist strain. The main variation was found in genes encoding the WiSP membrane protein family. This work also demonstrated a 19.2 kb-pair deletion within the T. whipplei DIG15 strain. This deletion occurs in the same region as the previously described large genomic rearrangement between Twist and TW08/27. Thus, this can be considered as a major hot-spot for intra-specific T. whipplei differentiation. Analysis of this deleted region confirmed the role of WND domains in generating T. whipplei diversity.
  
  
  CONCLUSIONS
  This work provides the first comprehensive genomic comparison of several T. whipplei isolates. It reveals that clinical isolates originating from various geographic and biological sources exhibit a high conservation rate, indicating that T. whipplei rarely interacts with exogenous DNA. Remarkably, frequent inter-strain variations were dicovered that affected members of the WiSP family.
authors.affiliation: Unité des Rickettsies, CNRS-UMR6020, IFR48, Faculté de Médecine, 27 Bd Jean Moulin, Marseille, F13385, France. my-van.la@medecine.univ-mrs.fr
authors.forename: My-Van
authors.initials: MV
authors.lastname: La
authors.forename: Nicolas
authors.initials: N
authors.lastname: Crapoulet
authors.forename: Pascal
authors.initials: P
authors.lastname: Barbry
authors.forename: Didier
authors.initials: D
authors.lastname: Raoult
authors.forename: Patricia
authors.initials: P
authors.lastname: Renesto
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D013045:Species Specificity; D054851:Tropheryma / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial