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Whole-genome sequencing of Leptospira interrogans from southern Brazil: genetic features of a highly virulent strain

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      BACKGROUNDLeptospirosis is the most widespread zoonotic disease. It is caused by infection with pathogenic Leptospira species, of which over 300 serovars have been described. The accurate identification of the causative Leptospira spp. is required to ascertain the pathogenic status of the local isolates.OBJECTIVESThis study aimed to obtain the complete genome sequence of a virulent Leptospira interrogans strain isolated from southern Brazil and to describe its genetic features.METHODSThe whole genome was sequenced by next-generation sequencing (Ion Torrent). The genome was assembled, scaffolded, annotated, and manually reviewed. Mutations were identified based on a variant calling analysis using the genome of L. interrogans strain Fiocruz L1-130 as a reference.FINDINGSThe entire genome had an average GC content of 35%. The variant calling analysis identified 119 single nucleotide polymorphisms (SNPs), from which 30 led to a missense mutation. The structural analyses identified potential evidence of genomic inversions, translocations, and deletions in both the chromosomes.MAIN CONCLUSIONSThe genome properties provide comprehensive information about the local isolates of Leptospira spp., and thereby, could facilitate the identification of new targets for the development of diagnostic kits and vaccines.

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      Most cited references 34

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      SPAdes: a new genome assembly algorithm and its applications to single-cell sequencing.

      The lion's share of bacteria in various environments cannot be cloned in the laboratory and thus cannot be sequenced using existing technologies. A major goal of single-cell genomics is to complement gene-centric metagenomic data with whole-genome assemblies of uncultivated organisms. Assembly of single-cell data is challenging because of highly non-uniform read coverage as well as elevated levels of sequencing errors and chimeric reads. We describe SPAdes, a new assembler for both single-cell and standard (multicell) assembly, and demonstrate that it improves on the recently released E+V-SC assembler (specialized for single-cell data) and on popular assemblers Velvet and SoapDeNovo (for multicell data). SPAdes generates single-cell assemblies, providing information about genomes of uncultivatable bacteria that vastly exceeds what may be obtained via traditional metagenomics studies. SPAdes is available online ( ). It is distributed as open source software.
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        A program for annotating and predicting the effects of single nucleotide polymorphisms, SnpEff: SNPs in the genome of Drosophila melanogaster strain w1118; iso-2; iso-3.

        We describe a new computer program, SnpEff, for rapidly categorizing the effects of variants in genome sequences. Once a genome is sequenced, SnpEff annotates variants based on their genomic locations and predicts coding effects. Annotated genomic locations include intronic, untranslated region, upstream, downstream, splice site, or intergenic regions. Coding effects such as synonymous or non-synonymous amino acid replacement, start codon gains or losses, stop codon gains or losses, or frame shifts can be predicted. Here the use of SnpEff is illustrated by annotating ~356,660 candidate SNPs in ~117 Mb unique sequences, representing a substitution rate of ~1/305 nucleotides, between the Drosophila melanogaster w(1118); iso-2; iso-3 strain and the reference y(1); cn(1) bw(1) sp(1) strain. We show that ~15,842 SNPs are synonymous and ~4,467 SNPs are non-synonymous (N/S ~0.28). The remaining SNPs are in other categories, such as stop codon gains (38 SNPs), stop codon losses (8 SNPs), and start codon gains (297 SNPs) in the 5'UTR. We found, as expected, that the SNP frequency is proportional to the recombination frequency (i.e., highest in the middle of chromosome arms). We also found that start-gain or stop-lost SNPs in Drosophila melanogaster often result in additions of N-terminal or C-terminal amino acids that are conserved in other Drosophila species. It appears that the 5' and 3' UTRs are reservoirs for genetic variations that changes the termini of proteins during evolution of the Drosophila genus. As genome sequencing is becoming inexpensive and routine, SnpEff enables rapid analyses of whole-genome sequencing data to be performed by an individual laboratory.
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          Artemis: sequence visualization and annotation.

          Artemis is a DNA sequence visualization and annotation tool that allows the results of any analysis or sets of analyses to be viewed in the context of the sequence and its six-frame translation. Artemis is especially useful in analysing the compact genomes of bacteria, archaea and lower eukaryotes, and will cope with sequences of any size from small genes to whole genomes. It is implemented in Java, and can be run on any suitable platform. Sequences and annotation can be read and written directly in EMBL, GenBank and GFF format. AVAILABITLTY: Artemis is available under the GNU General Public License from

            Author and article information

            Universidade Federal de Pelotas, Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Pelotas, RS, Brasil
            Author notes
            [+ ] Corresponding author: sergiojorgevet@


            SJ, FSK, NRO, VFC, LSP and OAD designed the study and wrote the manuscript; SJ and NRO performed the sequencing experiment; FSK, GOSVN, AMG, CDS and RDSW performed the bioinformatics analysis and created the figures and tables; KFR isolated the Piscina strain. All authors contributed to and revised the manuscript.

            The authors certify that they have no potential conflicts of interest.

            Mem Inst Oswaldo Cruz
            Mem. Inst. Oswaldo Cruz
            Memórias do Instituto Oswaldo Cruz
            Instituto Oswaldo Cruz, Ministério da Saúde
            February 2018
            February 2018
            : 113
            : 2
            : 80-86

            This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

            Figures: 2, Tables: 2, Equations: 0, References: 30, Pages: 7


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