Genome structure in the vole bacillus, Mycobacterium microti, a member of the Mycobacterium tuberculosis complex with a low virulence for humans

• Published in: Microbiology (Society for General Microbiology) 2004-05, Vol.150 (5), p.1519-1527
• Main Authors: Frota, Cristiane C, Hunt, Debbie M, Buxton, Roger S, Rickman, Lisa, Hinds, Jason, Kremer, Kristin, van Soolingen, Dick, Colston, M. Joseph
• Format: Article
• Language: English
• Subjects: Animals; Arvicolinae - microbiology; Bacillus; Bacterial Proteins - genetics; Gene Deletion; Genetic Variation; Genome, Bacterial; Genomics; Humans; Mycobacterium - chemistry; Mycobacterium - classification; Mycobacterium - genetics; Mycobacterium - pathogenicity; Mycobacterium bovis; Mycobacterium microti; Mycobacterium tuberculosis; Mycobacterium tuberculosis - classification; Mycobacterium tuberculosis - genetics; Oligonucleotide Array Sequence Analysis; Tuberculosis - microbiology; Virulence
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/mic.0.26660-0

1 Division of Mycobacterial Research, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK 2 Department of Medical Microbiology, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK 3 National Mycobacteria Reference Laboratory, National Institute of Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands Correspondence Roger S. Buxton rbuxton{at}nimr.mrc.ac.uk Mycobacterium microti , a member of the Mycobacterium tuberculosis complex, is phylogenetically closely related to M. tuberculosis , differing in a few biochemical properties. However, these species have different levels of virulence in different hosts; most notably M. microti shows lower virulence for humans than M. tuberculosis . This report presents genomic comparisons using DNA microarray analysis for an extensive study of the diversity of M. microti strains. Compared to M. tuberculosis H37Rv, 13 deletions were identified in 12 strains of M. microti , including the regions RD1 to RD10, which are also missing in Mycobacterium bovis BCG. In addition, four new deleted regions, named MiD1, RD1 , MiD2 and MiD3, were identified. DNA sequencing was used to define the extent of most of the deletions in one strain. Although RD1 of M. bovis BCG and M. microti is thought to be crucial for attenuation, in this study, three of the four M. microti strains that were isolated from immunocompetent patients had the RD1 deletion. In fact, only the RD3 deletion was present in all of the strains examined, although deletions RD7, RD8 and MiD1 were found in almost all the M. microti strains. These deletions might therefore have some relation to the different host range of M. microti . It was also noticeable that of the 12 strains studied, only three were identical; these strains were all isolated from immunocompetent humans, suggesting that they could have arisen from a single source. Thus, this study shows that it is difficult to ascribe virulence to any particular pattern of deletion in M. microti . Abbreviations: BCG, Mycobacterium bovis bacille Calmette-Guérin Deceased. Present address: Division of Medical Microbiology, Departamento de Patologia, Federal University of Ceara, Rua Monsenhor Furtado, S/N Rodolfo Teofilo, Fortaleza-Ceara, 60441-750, Brazil. Present address: The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK.