title: Use of highly variable intergenic spacer sequences for multispacer typing of Rickettsia conorii strains.
abstract: By use of the nearly perfectly colinear genomes of Rickettsia conorii and Rickettsia prowazekii, we compared the usefulness of three types of sequences for typing of R. conorii isolates: (i) 5 variable coding genes comprising the 16S ribosomal DNA, gltA, ompB, and sca4 (gene D) genes, which are present in both genomes, and the ompA gene, which is degraded in R. prowazekii; (ii) 28 genes degraded in R. conorii but intact in R. prowazekii, including 23 split and 5 remnant genes; and (iii) 27 conserved and 25 variable intergenic spacers. The 4 conserved and 23 split genes as well as the 27 conserved intergenic spacers each had identical sequences in 34 human and 5 tick isolates of R. conorii. Analysis of the ompA sequences identified three genotypes of R. conorii. The variable intergenic spacers were significantly more variable than conserved genes, split genes, remnant genes, and conserved spacers (P < 10(-2) in all cases). Four of the variable intergenic spacers (dksA-xerC, mppA-purC, rpmE-tRNA(fMet), and tRNA(Gly)-tRNA(Tyr)) had highly variable sequences; when they were combined for typing, multispacer typing (MST) identified 27 different genotypes in the 39 R. conorii isolates. Two batches from the same R. conorii strain, Malish (Seven), with different culture passage histories were found to exhibit the same MST type. MST was more discriminatory for strain genotyping than multiple gene sequencing (P < 10(-2)). Phylogenetic analysis based on MST sequences was concordant with the geographic origins of R. conorii isolates. Our study supports the usefulness of MST for strain genotyping. This tool may be useful for tracing a strain and identifying its source during outbreaks, including those resulting from bioterrorism.
authors.affiliation: Unité des Rickettsies, IFR 48, CNRS UMR 6020, Faculté de Médecine, Université de la Mediterranée, 27 Blvd. Jean Moulin, 13385 Marseille Cedex 5, France.
authors.forename: Pierre-Edouard
authors.initials: PE
authors.lastname: Fournier
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhu
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ogata
authors.forename: Didier
authors.initials: D
authors.lastname: Raoult
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D001483:Base Sequence; D001907:Boutonneuse Fever / Q000382:microbiology; D004269:DNA, Bacterial / Q000032:analysis; D021903:DNA, Ribosomal Spacer / Q000032:analysis*; D014644:Genetic Variation; D016680:Genome, Bacterial; D005838:Genotype; D006801:Humans; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012282:Rickettsia Infections / Q000382:microbiology; D020114:Rickettsia conorii / Q000145:classification* / Q000235:genetics / Q000254:growth & development; D012283:Rickettsia prowazekii / Q000145:classification / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S