Genomic variability of Mycobacterium tuberculosis strains of the Euro-American lineage based on large sequence deletions and 15-locus MIRU-VNTR polymorphism.

A sample of 260 Mycobacterium tuberculosis strains assigned to the Euro-American family was studied to identify phylogenetically informative genomic regions of difference (RD). Mutually exclusive deletions of regions RD115, RD122, RD174, RD182, RD183, RD193, RD219, RD726 and RD761 were found in 202 strains; the RD(Rio) deletion was detected exclusively among the RD174-deleted strains. Although certain deletions were found more frequently in certain spoligotype families (i.e., deletion RD115 in T and LAM, RD174 in LAM, RD182 in Haarlem, RD219 in T and RD726 in the "Cameroon" family), the RD-defined sublineages did not specifically match with spoligotype-defined families, thus arguing against the use of spoligotyping for establishing exact phylogenetic relationships between strains. Notably, when tested for katG463/gyrA95 polymorphism, all the RD-defined sublineages belonged to Principal Genotypic Group (PGG) 2, except sublineage RD219 exclusively belonging to PGG3; the 58 Euro-American strains with no deletion were of either PGG2 or 3. A representative sample of 197 isolates was then analyzed by standard 15-locus MIRU-VNTR typing, a suitable approach to independently assess genetic relationships among the strains. Analysis of the MIRU-VNTR typing results by using a minimum spanning tree (MST) and a classical dendrogram showed groupings that were largely concordant with those obtained by RD-based analysis. Isolates of a given RD profile show, in addition to closely related MIRU-VNTR profiles, related spoligotype profiles that can serve as a basis for better spoligotype-based classification.

Genetic diversity of human isolates of Mycobacterium bovis assessed by spoligotyping and Variable Number Tandem Repeat genotyping.

A collection of clinical isolates including 9 Mycobacterium bovis bacille Calmette-Guérin (BCG), 37 M. bovis and 1 isolate identified as M. bovis/caprae intermediate, recovered from humans in Tuscany, Italy, from 1990 to 2009, was genotyped by spoligotyping and Variable Number Tandem Repeat (VNTR) typing. Spoligotyping detected 15 unique profiles; the "BCG-like" SIT482/SB0120 spoligotype was largely prevalent accounting for 63.8% of isolates. VNTR typing, based on the 15 VNTR loci commonly tested for Mycobacterium tuberculosis, detected 29 unique profiles; only 8 VNTR loci (VNTR 43, MIRU 04, QUB-11b, ETR-A, VNTR 47, MIRU 31, QUB-26 and VNTR 53) provided a satisfactory allelic diversity in the VNTR analysis. Combined together, spoligotyping and VNTR typing yielded 33 unique patterns and 5 clusters including a total of 19 isolates. Clustered isolates, further typed for additional 9 VNTR loci, finally yielded 3 distinct clusters including 3 M. bovis BCG isolates each, and 1 cluster of 6 M. bovis isolates. Minimum spanning tree analysis showed that, in spite of the many distinct VNTR profiles, most M. bovis isolates displayed a high phylogenetic proximity, due to the variation of a single VNTR allele, thus indicating that the population of human M. bovis isolates in our setting is relatively homogeneous and conserved.