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Open Access Highly Accessed Research article

Mapping IS6110 in high-copy number Mycobacterium tuberculosis strains shows specific insertion points in the Beijing genotype

Henar Alonso134, Sofía Samper123, Carlos Martín123 and Isabel Otal13*

Author Affiliations

1 Grupo de Genética de Micobacterias. Departamento de Microbiología, Medicina Preventiva y Salud Pública, Universidad de Zaragoza, C/ Domingo Miral sn. 50009, Zaragoza, Spain

2 Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, IIS Aragón, Zaragoza, Spain

3 CIBER Enfermedades Respiratorias (CIBERES), Madrid, Spain

4 Institut de Pharmacologie et de Biologie Structurale, UMR5089 CNRS, 205 Route de Narbonne, BP 64182, 31077 Toulouse France

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BMC Genomics 2013, 14:422  doi:10.1186/1471-2164-14-422

Published: 25 June 2013

Abstract

Background

Mycobacterium tuberculosis Beijing strains are characterized by a large number of IS6110 copies, suggesting the potential implication of this element in the virulence and capacity for rapid dissemination characteristic of this family. This work studies the insetion points of IS6110 in high-copy clinical isolates specifically focusing on the Beijing genotype.

Results

In the present work we mapped the insertion points of IS6110 in all the Beijing strains available in the literature and in the DNA sequence databases. We generated a representative primer collection of the IS6110 locations, which was used to analyse 61 high-copy clinical isolates. A total of 440 points of insertion were identified and analysis of their flanking regions determined the exact location, the direct repeats (DRs), the orientation and the distance to neighboring genes of each copy of IS6110. We identified specific points of insertion in Beijing strains that enabled us to obtain a dendrogram that groups the Beijing genotype.

Conclusions

This work presents a detailed analysis of locations of IS6110 in high-copy clinical isolates, showing points of insertion present with high frequency in the Beijing family and absent in other strains.

Keywords:
IS6110; Insertion points; M. tuberculosis; Beijing genotype