Bioinformatics describes novel Loci for high resolution discrimination of leptospira isolates.
BACKGROUND
Leptospirosis is one of the most widespread zoonoses in the world and with over 260 pathogenic serovars there is an urgent need for a molecular system of classification. The development of multilocus sequence typing (MLST) schemes for Leptospira spp. is addressing this issue. The aim of this study was to identify loci with potential to enhance Leptospira strain discrimination by sequencing-based methods.


RESULTS
We used bioinformatics to evaluate pre-existing loci with the potential to increase the discrimination of outbreak strains. Previously deposited sequence data were evaluated by phylogenetic analyses using either single or concatenated sequences. We identified and evaluated the applicability of the ligB, secY, rpoB and lipL41 loci, individually and in combination, to discriminate between 38 pathogenic Leptospira strains and to cluster them according to the species they belonged to. Pairwise identity among the loci ranged from 82.0-92.0%, while interspecies identity was 97.7-98.5%. Using the ligB-secY-rpoB-lipL41 superlocus it was possible to discriminate 34/38 strains, which belong to six pathogenic Leptospira species. In addition, the sequences were concatenated with the superloci from 16 sequence types from a previous MLST scheme employed to study the association of a leptospiral clone with an outbreak of human leptospirosis in Thailand. Their use enhanced the discriminative power of the existing scheme. The lipL41 and rpoB loci raised the resolution from 81.0-100%, but the enhanced scheme still remains limited to the L. interrogans and L. kirschneri species.


CONCLUSIONS
As the first aim of our study, the ligB-secY-rpoB-lipL41 superlocus demonstrated a satisfactory level of discrimination among the strains evaluated. Second, the inclusion of the rpoB and lipL41 loci to a MLST scheme provided high resolution for discrimination of strains within L. interrogans and L. kirschneri and might be useful in future epidemiological studies.
Centro de Biotecnologia, Instituto Butantan, São Paulo, Brazil. cerqueiragm@yahoo.com.br
Gustavo M
GM
Cerqueira
Alan J A
AJ
McBride
Rudy A
RA
Hartskeerl
Niyaz
N
Ahmed
Odir A
OA
Dellagostin
Marcus R
MR
Eslabão
Ana L T O
AL
Nascimento
D001483:Base Sequence; D017931:DNA Primers; D007919:Leptospira / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D013045:Species Specificity
D017931:DNA Primers