S10-spc-α is a 17.5 kb cluster of 32 genes encoding ribosomal proteins. This locus has an unusual composition and organization in
Leptospira interrogans. We demonstrate the highly conserved nature of this region among diverse
Leptospira and show its utility as a phylogenetically informative region. Comparative analyses were performed by PCR using primer sets covering the whole locus. Correctly sized fragments were obtained by PCR from all
L. interrogans strains tested for each primer set indicating that this locus is well conserved in this species. Few differences were detected in amplification profiles between different pathogenic species, indicating that the
S10-spc-α locus is conserved among pathogenic
Leptospira. In contrast, PCR analysis of this locus using DNA from saprophytic
Leptospira species and species with an intermediate pathogenic capacity generated varied results. Sequence alignment of the
S10-spc-α locus from two pathogenic species,
L. interrogans and
L. borgpetersenii, with the corresponding locus from the saprophyte
L. biflexa serovar Patoc showed that genetic organization of this locus is well conserved within
Leptospira. Multilocus sequence typing (MLST) of four conserved regions resulted in the construction of well-defined phylogenetic trees that help resolve questions about the interrelationships of pathogenic
Leptospira. Based on the results of
secY sequence analysis, we found that reliable species identification of pathogenic
Leptospira is possible by comparative analysis of a 245 bp region commonly used as a target for diagnostic PCR for leptospirosis. Comparative analysis of
Leptospira strains revealed that strain H6 previously classified as
L. inadai actually belongs to the pathogenic species
L. interrogans and that
L. meyeri strain ICF phylogenetically co-localized with the pathogenic clusters. These findings demonstrate that the
S10-spc-α locus is highly conserved throughout the genus and may be more useful in comparing evolution of the genus than loci studied previously.
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