Affiliation:
1. Unité des Rickettsies, IFR 48, CNRS UMR 6020, Faculté de Médecine, Université de la Méditerranée
2. Information Génomique et Structurale, CNRS UPR2589, Marseille, France
Abstract
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.
Publisher
American Society for Microbiology
Cited by
80 articles.
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