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1.  Mycobacterium tuberculosis Strains of the Modern Sublineage of the Beijing Family Are More Likely To Display Increased Virulence than Strains of the Ancient Sublineage 
Journal of Clinical Microbiology  2014;52(7):2615-2624.
Strains of the Beijing genotype family of Mycobacterium tuberculosis are a cause of particular concern because of their increasing dissemination in the world and their association with drug resistance. Phylogenetically, this family includes distinct ancient and modern sublineages. The modern strains, contrary to the ancestral counterparts, demonstrated increasing prevalence in many world regions that suggest an enhanced bacterial pathogenicity. We therefore evaluated virulence of modern versus ancient Beijing strains with similar epidemiological and genotype characteristics. For this, we selected six strains that had very similar 24-locus mycobacterial interspersed repetitive-unit–variable-number tandem-repeat (MIRU-VNTR) typing profiles and belonged to the region of difference 181 (RD181) subgroup but differed using markers (mutT2 and mutT4 genes and NTF locus) that discriminate between modern and ancient Beijing sublineages. The strains were isolated from native patients in Brazil and Mozambique, countries with a low prevalence of Beijing strains. The virulence levels of these strains were determined in models of pulmonary infection in mice and in vitro macrophage infection and compared with that of a strain from Russia, part of the epidemic and hypervirulent Beijing clone B0/W148, and of the laboratory strain H37Rv. The results showed that two of the three modern Beijing strains were highly pathogenic, exhibiting levels of virulence comparable with that of the epidemic Russian strain. In contrast, all isolates of the ancient sublineage displayed intermediate or low virulence. The data obtained demonstrate that the strains of the modern Beijing sublineage are more likely to exhibit highly virulent phenotypes than ancient strains and suggest that genetic alterations characteristic of the modern Beijing sublineage favor selection of highly virulent bacteria.
PMCID: PMC4097719  PMID: 24829250
2.  Mycobacterium tuberculosis Latin American-Mediterranean Family and Its Sublineages in the Light of Robust Evolutionary Markers 
Journal of Bacteriology  2014;196(10):1833-1841.
Mycobacterium tuberculosis has a clonal population structure, and the Latin American-Mediterranean (LAM) family is one of the largest and most widespread within this species, showing evidence for remarkable pathobiology and a confusing phylogeny. Here, we applied robust phylogenetic markers to study the evolution of the LAM family and its major sublineages circulating in Russia and neighboring countries. A total of 250 M. tuberculosis isolates were confirmed to belong to the LAM family based on the analysis of the LAM-specific single-nucleotide polymorphisms (SNPs) in the Rv3062 and Rv0129c genes. At this stage, the family status was rectified for 121 isolates misleadingly assigned by CRISPR spoligotyping to non-LAM families (T1- or T5-RUS1). Consequently, the reestimated LAM prevalence rate increased 2-fold in Russia and Kazakhstan and 4-fold in Belarus. The majority (91.8 to 98.7%) of the LAM isolates from all three countries belonged to the LAM-RUS sublineage. In contrast, the Ibero-American LAM RD-Rio sublineage was identified in only 7 Russian isolates. Taken together, our findings and further analyses suggest a monophyletic origin of LAM-RUS: at a historically distant time, in Russia, in a small founding bacterial/human population. Its dissemination pattern and high prevalence rate in Northern Eurasia may indicate a long-term coexistence of the LAM-RUS sublineage and local human populations hypothetically leading to coadaptation and reduced pathogenicity of the relatively more ancient clones, such as spoligotype international type 254 (SIT254), compared to the more recent SIT252 and SIT266 clones. In contrast, rare LAM RD-Rio isolates were likely brought to Russia through occasional human contact. The spread of RD-Rio strains is not as global as commonly claimed and is determined largely by human migration flows (rather than by pathobiological properties of these strains). Consequently, a host population factor appears to play a major role in shaping the in situ dissemination pattern of the imported strains in an autochthonous population.
PMCID: PMC4011003  PMID: 24584500
3.  Real-Time PCR Assay for Rapid Detection of Epidemiologically and Clinically Significant Mycobacterium tuberculosis Beijing Genotype Isolates 
Journal of Clinical Microbiology  2014;52(5):1691-1693.
Mycobacterium tuberculosis Beijing genotype strains are rapidly disseminating, frequently hypervirulent, and multidrug resistant. Here, we describe a method for their rapid detection by real-time PCR that targets the specific IS6110 insertion in the dnaA-dnaN genome region. The method was evaluated with a geographically and genetically diverse collection representing areas in East Asia and the former Soviet Union in which the Beijing genotype is endemic and epidemic (i.e., major foci of its global propagation) and with clinical specimens.
PMCID: PMC3993684  PMID: 24523461
4.  Resolution Threshold of Current Molecular Epidemiology of Diphtheria 
Emerging Infectious Diseases  2014;20(11):1937-1938.
PMCID: PMC4214297  PMID: 25340886
diphtheria; Corynebacterium diphtheriae; bacteria; genotyping; genomics; molecular epidemiology; clusters; whole-genome sequencing; pulsed-field gel electrophoresis; multilocus sequence typing; regularly interspaced short palindromic repeats
5.  Proposal of a Consensus Set of Hypervariable Mycobacterial Interspersed Repetitive-Unit–Variable-Number Tandem-Repeat Loci for Subtyping of Mycobacterium tuberculosis Beijing Isolates 
Journal of Clinical Microbiology  2014;52(1):164-172.
Mycobacterium tuberculosis Beijing strains represent targets of special importance for molecular surveillance of tuberculosis (TB), especially because they are associated with spread of multidrug resistance in some world regions. Standard 24-locus mycobacterial interspersed repetitive-unit–variable-number tandem-repeat (MIRU-VNTR) typing lacks resolution power for accurately discriminating closely related clones that often compose Beijing strain populations. Therefore, we evaluated a set of 7 additional, hypervariable MIRU-VNTR loci for better resolution and tracing of such strains, using a collection of 535 Beijing isolates from six world regions where these strains are known to be prevalent. The typeability and interlaboratory reproducibility of these hypervariable loci were lower than those of the 24 standard loci. Three loci (2163a, 3155, and 3336) were excluded because of their redundant variability and/or more frequent noninterpretable results compared to the 4 other markers. The use of the remaining 4-locus set (1982, 3232, 3820, and 4120) increased the number of types by 52% (from 223 to 340) and reduced the clustering rate from 58.3 to 36.6%, when combined with the use of the standard 24-locus set. Known major clonal complexes/24-locus-based clusters were all subdivided, although the degree of subdivision varied depending on the complex. Only five single-locus variations were detected among the hypervariable loci of an additional panel of 92 isolates, representing 15 years of clonal spread of a single Beijing strain in a geographically restricted setting. On this calibrated basis, we propose this 4-locus set as a consensus for subtyping Beijing clonal complexes and clusters, after standard typing.
PMCID: PMC3911419  PMID: 24172154
6.  Genome-wide Mycobacterium tuberculosis variation (GMTV) database: a new tool for integrating sequence variations and epidemiology 
BMC Genomics  2014;15:308.
Tuberculosis (TB) poses a worldwide threat due to advancing multidrug-resistant strains and deadly co-infections with Human immunodeficiency virus. Today large amounts of Mycobacterium tuberculosis whole genome sequencing data are being assessed broadly and yet there exists no comprehensive online resource that connects M. tuberculosis genome variants with geographic origin, with drug resistance or with clinical outcome.
Here we describe a broadly inclusive unifying Genome-wide Mycobacterium tuberculosis Variation (GMTV) database, ( that catalogues genome variations of M. tuberculosis strains collected across Russia. GMTV contains a broad spectrum of data derived from different sources and related to M. tuberculosis molecular biology, epidemiology, TB clinical outcome, year and place of isolation, drug resistance profiles and displays the variants across the genome using a dedicated genome browser. GMTV database, which includes 1084 genomes and over 69,000 SNP or Indel variants, can be queried about M. tuberculosis genome variation and putative associations with drug resistance, geographical origin, and clinical stages and outcomes.
Implementation of GMTV tracks the pattern of changes of M. tuberculosis strains in different geographical areas, facilitates disease gene discoveries associated with drug resistance or different clinical sequelae, and automates comparative genomic analyses among M. tuberculosis strains.
PMCID: PMC4234438  PMID: 24767249
Mycobacterium tuberculosis; Genome variations; Mutation; Genetic diversity; Whole genome sequencing; Database
7.  Insights into the Origin, Emergence, and Current Spread of a Successful Russian Clone of Mycobacterium tuberculosis 
Clinical Microbiology Reviews  2013;26(2):342-360.
Mycobacterium tuberculosis variant Beijing B0/W148 is regarded as a successful clone of M. tuberculosis that is widespread in the former Soviet Union and respective immigrant communities. Understanding the pathobiology and phylogeography of this notorious strain may help to clarify its origin and evolutionary history and the driving forces behind its emergence and current dissemination. I present the first review and analysis of all available data on the subject. In spite of the common perception of the omnipresence of B0/W148 across post-Soviet countries, its geographic distribution shows a peculiar clinal gradient. Its frequency peaks in Siberian Russia and, to a lesser extent, in the European part of the former Soviet Union. In contrast, the frequency of B0/W148 is sharply decreased in the Asian part of the former Soviet Union, and it is absent in autochthonous populations elsewhere in the world. Placing the molecular, clinical, and epidemiological features in a broad historical, demographic, and ecological context, I put forward two interdependent hypotheses. First, B0/W148 likely originated in Siberia, and its primary dispersal was driven by a massive population outflow from Siberia to European Russia in the 1960s to 1980s. Second, a historically recent, phylogenetically demonstrated successful dissemination of the Beijing B0/W148 strain was triggered by the advent and wide use of modern antituberculosis (anti-TB) drugs and was due to the remarkable capacity of this strain to acquire drug resistance. In contrast, there is some indication, but not yet systematic proof, of an enhanced virulence of this strain.
PMCID: PMC3623382  PMID: 23554420
8.  Tuberculosis Epidemiology and Selection in an Autochthonous Siberian Population from the 16th-19th Century 
PLoS ONE  2014;9(2):e89877.
Tuberculosis is one of most ancient diseases affecting human populations. Although numerous studies have tried to detect pathogenic DNA in ancient skeletons, the successful identification of ancient tuberculosis strains remains rare. Here, we describe a study of 140 ancient subjects inhumed in Yakutia (Eastern Siberia) during a tuberculosis outbreak, dating from the 16th–19th century. For a long time, Yakut populations had remained isolated from European populations, and it was not until the beginning of the 17th century that first contacts were made with European settlers. Subsequently, tuberculosis spread throughout Yakutia, and the evolution of tuberculosis frequencies can be tracked until the 19th century. This study took a multidisciplinary approach, examining historical and paleo-epidemiological data to understand the impact of tuberculosis on ancient Yakut population. In addition, molecular identification of the ancient tuberculosis strain was realized to elucidate the natural history and host-pathogen co-evolution of human tuberculosis that was present in this population. This was achieved by the molecular detection of the IS6110 sequence and SNP genotyping by the SNaPshot technique. Results demonstrated that the strain belongs to cluster PGG2-SCG-5, evocating a European origin. Our study suggests that the Yakut population may have been shaped by selection pressures, exerted by several illnesses, including tuberculosis, over several centuries. This confirms the validity and necessity of using a multidisciplinary approach to understand the natural history of Mycobacterium tuberculosis infection and disease.
PMCID: PMC3935942  PMID: 24587092
9.  Unusual Large-Scale Chromosomal Rearrangements in Mycobacterium tuberculosis Beijing B0/W148 Cluster Isolates 
PLoS ONE  2014;9(1):e84971.
The Mycobacterium tuberculosis (MTB) Beijing family isolates are geographically widespread, and there are examples of Beijing isolates that are hypervirulent and associated with drug resistance. One-fourth of Beijing genotype isolates found in Russia belong to the B0/W148 group. The aim of the present study was to investigate features of these endemic strains on a genomic level. Four Russian clinical isolates of this group were sequenced, and the data obtained was compared with published sequences of various MTB strain genomes, including genome of strain W-148 of the same B0/W148 group. The comparison of the W-148 and H37Rv genomes revealed two independent inversions of large segments of the chromosome. The same inversions were found in one of the studied strains after deep sequencing using both the fragment and mate-paired libraries. Additionally, inversions were confirmed by RFLP hybridization analysis. The discovered rearrangements were verified by PCR in all four newly sequenced strains in the study and in four additional strains of the same Beijing B0/W148 group. The other 32 MTB strains from different phylogenetic lineages were tested and revealed no inversions. We suggest that the initial largest inversion changed the orientation of the three megabase (Mb) segment of the chromosome, and the second one occurred in the previously inverted region and partly restored the orientation of the 2.1 Mb inner segment of the region. This is another remarkable example of genomic rearrangements in the MTB in addition to the recently published of large-scale duplications. The described cases suggest that large-scale genomic rearrangements in the currently circulating MTB isolates may occur more frequently than previously considered, and we hope that further studies will help to determine the exact mechanism of such events.
PMCID: PMC3885621  PMID: 24416324
10.  Russian “Successful” Clone B0/W148 of Mycobacterium tuberculosis Beijing Genotype: a Multiplex PCR Assay for Rapid Detection and Global Screening 
Journal of Clinical Microbiology  2012;50(11):3757-3759.
We describe a multiplex PCR assay to detect the Mycobacterium tuberculosis Beijing genotype variant B0/W148, which is considered a “successful” clone of M. tuberculosis, widespread in Russia. Specificity and sensitivity of the assay were 100% based on the analysis of a collection of 516 M. tuberculosis isolates of different genotypes and origins. This assay may be used for accurate and simple detection and surveillance of this clinically and epidemiologically important variant of M. tuberculosis.
PMCID: PMC3486266  PMID: 22933595
13.  Correction: Tag SNP Polymorphism of CCL2 and Its Role in Clinical Tuberculosis in Han Chinese Pediatric Population 
PLoS ONE  2011;6(4):10.1371/annotation/675f01a0-0f6e-4eb5-8cb1-ee8c5b5cbfe3.
PMCID: PMC3071857
14.  Tag SNP Polymorphism of CCL2 and Its Role in Clinical Tuberculosis in Han Chinese Pediatric Population 
PLoS ONE  2011;6(2):e14652.
Chemokine (C-C motif) ligand 2 CCL2/MCP-1 is among the key signaling molecules of innate immunity; in particular, it is involved in recruitment of mononuclear and other cells in response to infection, including tuberculosis (TB) and is essential for granuloma formation.
Methodology/Principal Findings
We identified a tag SNP for the CCL2/MCP-1 gene (rs4586 C/T). In order to understand whether this SNP may serve to evaluate the contribution of the CCL2 gene to the expression of TB disease, we further analysed distribution of its alleles and genotypes in 301 TB cases versus 338 non-infected controls (all BCG vaccinated) representing a high-risk pediatric population of North China. In the male TB subgroup, the C allele was identified in a higher rate (P = 0.045), and, acting dominantly, was found to be a risk factor for clinical TB (P = 0.029). Homozygous TT genotype was significantly associated with lower CSF mononuclear leukocyte (ML) counts in patients with tuberculous meningitis (TBM) (P = 0.001).
The present study found an association of the CCL2 tag SNP rs4586 C allele and pediatric TB disease in males, suggesting that gender may affect the susceptibility to TB even in children. The association of homozygous TT genotype with decreased CSF mononuclear leukocyte (ML) count not only suggests a clinical significance of this SNP, but indicates its potential to assist in the clinical assessment of suspected TBM, where delay is critical and diagnosis is difficult.
PMCID: PMC3084193  PMID: 21556333
16.  Mycobacterium tuberculosis Beijing Genotype in Russia: in Search of Informative Variable-Number Tandem-Repeat Loci▿ † 
Journal of Clinical Microbiology  2008;46(11):3576-3584.
The Beijing genotype is a globally spread lineage of Mycobacterium tuberculosis. In Russia, these strains constitute half of the local population of M. tuberculosis; they are associated with multidrug resistance and show increased transmissibility. Here, we analyzed traditional and new markers for the rapid and simple genotyping of the Beijing strains. A representative sample of 120 Beijing genotype strains was selected from a local IS6110-restriction fragment length (RFLP) database at the St. Petersburg Pasteur Institute. These strains were subjected to variable-number tandem-repeat (VNTR) typing using 24 loci of a newly proposed format and three hypervariable (HV) loci (QUB-3232, VNTR-3820, and VNTR-4120). Ten of the 27 VNTR loci were monomorphic, while five loci, MIRU26, QUB-26, QUB-3232, VNTR-3820, and VNTR-4120, were the most polymorphic (Hunter Gaston index, >0.5). VNTR typing allowed us to differentiate between two large IS6110-RFLP clusters known to be prevalent across the entire country (clusters B0/W148 and A0) and identified in 27 and 23% of strains, respectively, in the Beijing genotype database. The B0/W148 strains were grouped closely in the VNTR dendrogram and could be distinguished by a characteristic signature of the loci MIRU26 and QUB-26. Consequently, this clinically important IS6110-RFLP variant, B0/W148, likely presents a successful clonal group within the M. tuberculosis Beijing lineage that is widespread in Russia. To conclude, the IS6110-RFLP method and VNTR typing using a reduced set of the most polymorphic loci complement each other for the high-resolution epidemiological typing of the M. tuberculosis Beijing genotype strains circulating in or imported from Russia.
PMCID: PMC2576596  PMID: 18753356
17.  Utility of New 24-Locus Variable-Number Tandem-Repeat Typing for Discriminating Mycobacterium tuberculosis Clinical Isolates Collected in Bulgaria▿ † 
Journal of Clinical Microbiology  2008;46(9):3005-3011.
The present study evaluated new markers for molecular typing of Mycobacterium tuberculosis with a collection of strains circulating in Bulgaria. A study sample included 133 strains from epidemiologically unlinked patients from different regions of the country. Spoligotyping was used as a primary typing tool; it subdivided these strains into 37 types, including 15 clusters and 22 singletons. Traditional IS6110-restriction fragment length polymorphism (RFLP) typing and novel 24-locus variable number tandem-repeat (VNTR) typing methods were applied to the selection of 73 strains. Discriminatory power (Hunter-Gaston index [HGI]) of these methods was found to be 0.983 and 0.997, respectively. The 73 strains were subdivided into 66 types by a 24-locus mycobacterial interspersed repetitive unit (MIRU)-VNTR scheme, 62 types by a classical 12-locus MIRU-VNTR scheme, 51 types by IS6110-RFLP typing, and 31 types by spoligotyping. A combination of the five most polymorphic loci (MIRU40, Mtub04, Mtub21, QUB-11b, and QUB-26) was shown to achieve a high discrimination (HGI = 0.984). To conclude, a complete 24-locus scheme excellently differentiated strains in our study, whereas a reduced 5-locus set provided a sufficiently high differentiation and may be preliminarily suggested for the first-line typing of M. tuberculosis isolates in Bulgaria.
PMCID: PMC2546716  PMID: 18614651
18.  Molecular Characterization of Ofloxacin-Resistant Mycobacterium tuberculosis Strains from Russia▿ †  
In this work, we studied the variation in the gyrA and gyrB genes in ofloxacin- and multidrug-resistant Mycobacterium tuberculosis strains circulating in northwest Russia. Comparison with spoligotyping data suggested that similar to the spread of multidrug-resistant tuberculosis, the spread of fluoroquinolone-resistant tuberculosis in Russia may be due, at least partly, to the prevalence of the Beijing genotype in a local population of M. tuberculosis.
PMCID: PMC2493099  PMID: 18559646
19.  Evaluation of New Variable-Number Tandem-Repeat Systems for Typing Mycobacterium tuberculosis with Beijing Genotype Isolates from Beijing, China▿  
Journal of Clinical Microbiology  2008;46(3):1045-1049.
The newly proposed variable-number tandem-repeat (VNTR) typing system, which includes a basic 15-locus set and a high-resolution 24-locus set (P. Supply et al., J. Clin. Microbiol. 44:4498-4510, 2006), demonstrated a high power for the discrimination of Mycobacterium tuberculosis isolates collected worldwide. To evaluate its ability to differentiate the Beijing genotype strains from the Beijing area in China, 72 isolates with typical Beijing or Beijing-like spacer oligonucleotide typing profiles were subjected to typing with the VNTR system (24 loci) and typing by restriction fragment polymorphism analysis with IS6110 (IS6110-RFLP). Compared to the “old” 12-locus VNTR typing method, use of the 15- and 24-locus systems had a dramatically improved power to discriminate the Beijing genotype strains. A subtle difference in the Hunter-Gaston discriminatory index (HGI) between the 15-locus and the 24-locus systems resulted from only one locus, Mtub29. However, the VNTR-based clusters could be further differentiated by IS6110-RFLP (HGI by IS6110 RFLP, 0.999), although in one case an IS6110 cluster was subdivided by the 15-locus VNTR system. In this sense, use of the newly proposed 15-locus VNTR system along with the Mtub29 locus can serve as a first-line typing method for the epidemiological study of M. tuberculosis isolates in Beijing, while secondary typing of clustered strains by IS6110-RFLP is still required.
PMCID: PMC2268385  PMID: 18199785
20.  Molecular Characterization of Mycobacterium tuberculosis Isolates from Different Regions of Bulgaria▿  
Journal of Clinical Microbiology  2008;46(3):1014-1018.
Mycobacterium tuberculosis isolates from different regions of Bulgaria were studied by a variety of molecular typing tools. Based on spacer oligonucleotide typing (spoligotyping), the 113 strains were subdivided into 35 spoligotypes: 5 unique profiles and 15 profiles shared by two to 29 strains; the Hunter-Gaston diversity index (HGI) was 0.9. Comparison with the international database SITVIT2 at the Institut Pasteur de Guadeloupe showed the presence of two globally distributed shared types, ST53 (25.7%) and ST47 (6.2%). Nineteen (16.8%) and six (5.3%) strains belonged to the ST125 (LAM/S subfamily) and ST41 (LAM7_TUR subfamily) types described in SITVIT2 as ubiquitous/rare and ubiquitous/common types, respectively. Seven spoligoprofiles (12 strains) were not found in the database; two of them constituted new shared types. The Beijing genotype strains were not found in the studied collection in spite of close contacts with Russia in the recent and historical past. Additional subtyping by IS6110-restriction fragment length polymorphism (RFLP) and 12-locus mycobacterial interspersed repetitive unit (MIRU)-variable number of tandem repeat analyses were performed within selected spoligotypes. In particular, MIRU typing showed better discrimination within ST125 than IS6110-RFLP typing (HGI = 0.83 versus 0.39). A high gradient for ST125 in Bulgaria compared to its negligible presence in the global database and neighboring countries leads us to suggest a Bulgarian phylogeographic specificity of this spoligotype. To conclude, this first study of the Bulgarian M. tuberculosis population demonstrated its heterogeneity and predominance of several worldwide-distributed and Balkan-specific spoligotypes.
PMCID: PMC2268356  PMID: 18199794
22.  Rapid Detection of the Mycobacterium tuberculosis Beijing Genotype and Its Ancient and Modern Sublineages by IS6110-Based Inverse PCR 
Journal of Clinical Microbiology  2006;44(8):2851-2856.
The Mycobacterium tuberculosis Beijing genotype strains appear to be hypervirulent and associated with multidrug-resistant tuberculosis. Therefore, the development of a both rapid and simple method to detect the M. tuberculosis Beijing genotype is of clinical interest per se. Previously, we described a simple and fast approach to detect the Beijing genotype based on IS6110 inverse-PCR typing. Here, we evaluated this method against a large, diverse, and recent collection of strains. The study sample included 866 M. tuberculosis strains representing but not limited to the regions in Russia, Europe, and East Asia where the Beijing genotype is endemic. Based on a spoligotyping method, 408 strains were identified as Beijing genotypes; they were additionally subdivided into ancient and modern sublineages based on the analysis of the NTF locus. All strains were further subjected to the IS6110-based inverse PCR. All of the Beijing genotype strains were found to have identical two-band (ancient sublineage) or three-band (modern sublineage) profiles that were easily recognizable and distinct from the profiles of the non-Beijing strains. Therefore, we suggest using IS6110-based inverse-PCR typing for the correct identification of the Beijing genotype and its major sublineages. The method is fast and inexpensive and does not require additional experiments but instead is implemented in the routine typing method of M. tuberculosis.
PMCID: PMC1594662  PMID: 16891502
23.  Evolution of Drug Resistance in Different Sublineages of Mycobacterium tuberculosis Beijing Genotype 
We compared the population structure and drug resistance patterns of the Mycobacterium tuberculosis strains currently circulating in the Beijing area of China. One hundred thirteen of 123 strains belonged to the Beijing family genotypes defined by spoligotyping. The Beijing genotype strains were further subdivided into old and modern sublineages on the basis of NTF locus analysis. A stronger association with resistance to the more recently introduced antituberculosis drugs has been observed for old versus modern strains of the Beijing genotype, suggesting that its different sublineages may differ in their mechanisms of adaptation to drug selective pressure.
PMCID: PMC1538659  PMID: 16870777
24.  Mycobacterium tuberculosis Beijing Genotype and Mycobacterial Interspersed Repetitive Unit Typing 
Journal of Clinical Microbiology  2006;44(4):1614-1615.
PMCID: PMC1448646  PMID: 16597915
25.  Mycobacterium tuberculosis complex genetic diversity: mining the fourth international spoligotyping database (SpolDB4) for classification, population genetics and epidemiology 
BMC Microbiology  2006;6:23.
The Direct Repeat locus of the Mycobacterium tuberculosis complex (MTC) is a member of the CRISPR (Clustered regularly interspaced short palindromic repeats) sequences family. Spoligotyping is the widely used PCR-based reverse-hybridization blotting technique that assays the genetic diversity of this locus and is useful both for clinical laboratory, molecular epidemiology, evolutionary and population genetics. It is easy, robust, cheap, and produces highly diverse portable numerical results, as the result of the combination of (1) Unique Events Polymorphism (UEP) (2) Insertion-Sequence-mediated genetic recombination. Genetic convergence, although rare, was also previously demonstrated. Three previous international spoligotype databases had partly revealed the global and local geographical structures of MTC bacilli populations, however, there was a need for the release of a new, more representative and extended, international spoligotyping database.
The fourth international spoligotyping database, SpolDB4, describes 1939 shared-types (STs) representative of a total of 39,295 strains from 122 countries, which are tentatively classified into 62 clades/lineages using a mixed expert-based and bioinformatical approach. The SpolDB4 update adds 26 new potentially phylogeographically-specific MTC genotype families. It provides a clearer picture of the current MTC genomes diversity as well as on the relationships between the genetic attributes investigated (spoligotypes) and the infra-species classification and evolutionary history of the species. Indeed, an independent Naïve-Bayes mixture-model analysis has validated main of the previous supervised SpolDB3 classification results, confirming the usefulness of both supervised and unsupervised models as an approach to understand MTC population structure. Updated results on the epidemiological status of spoligotypes, as well as genetic prevalence maps on six main lineages are also shown. Our results suggests the existence of fine geographical genetic clines within MTC populations, that could mirror the passed and present Homo sapiens sapiens demographical and mycobacterial co-evolutionary history whose structure could be further reconstructed and modelled, thereby providing a large-scale conceptual framework of the global TB Epidemiologic Network.
Our results broaden the knowledge of the global phylogeography of the MTC complex. SpolDB4 should be a very useful tool to better define the identity of a given MTC clinical isolate, and to better analyze the links between its current spreading and previous evolutionary history. The building and mining of extended MTC polymorphic genetic databases is in progress.
PMCID: PMC1468417  PMID: 16519816

Results 1-25 (37)