A novel Ancestral Beijing sublineage of Mycobacterium tuberculosis suggests the transition site to Modern Beijing sublineages

Mycobacterium tuberculosis Beijing in the State of Nuevo Leon, Mexico

Tuberculosis remains a serious threat to human health as an infectious disease in Mexico. Data about the genotypes of circulating Mycobacterium tuberculosis isolates (MTB) in the State of Nuevo Leon, Mexico are scarce. We aimed to determine the genotypes of circulating MTB belonging to the Beijing lineage recovered from patients in the State of Nuevo Leon, Mexico. A total of 406 MTB isolates from this state were genotyped using the spoligotyping method and 18-locus MIRU-VNTR. Lineage classification and MTB transmission analysis were performed. Based on the spoligotyping analysis, we found 24 strains belonging to the Beijing genotype that were characterized phylogenetically. The MIRUs showed greater discriminatory power than the standard RFLP-IS6110 method; therefore, the greatest allelic diversity among the Beijing strains was observed with MIRU10, MIRU31, MIRU39, MRU40, and MIRU 26. MVLA analysis showed a profile variation between Beijing and non-Beijing strains. The minimum spanning tree (MST) showed that 79% (19) of the strains are related. All Beijing strains exhibited the deletion of region TbD1, which is a characteristic of modern strains. The application of spoligotyping and MIRU-VNTR-18 methods together proved to be more sensitive, discriminatory, and rapid than the standard method for the epidemiological analysis of Mycobacterium Beijing isolates. This study is one of the first to describe the genomic diversity of M. Beijing in the State of Nuevo Leon, Mexico.

Genetic diversity, evolution and drug resistance of Mycobacterium tuberculosis lineage 2

Mycobacterium tuberculosis causes a chronic infectious disease called tuberculosis. Phylogenetic lineage 2 (L2) of M. tuberculosis, also known as the East Asian lineage, is associated with high virulence, increased transmissibility, and the spread of multidrug-resistant strains. This review article examines the genomic characteristics of the M. tuberculosis genome and M. tuberculosis lineage 2, such as the unique insertion sequence and spoligotype patterns, as well as MIRU-VNTR typing, and SNP-based barcoding. The review describes the geographical distribution of lineage 2 and its history of origin. In addition, the article discusses recent studies on drug resistance and compensatory mechanisms of M. tuberculosis lineage 2 and its impact on the pathogen's transmissibility and virulence. This review article discusses the importance of establishing a unified classification for lineage 2 to ensure consistency in terminology and criteria across different studies and settings.

The first insight into Mycobacterium tuberculosis complex isolates in the lower northern region in Thailand

BACKGROUND

Tuberculosis (TB) remains an important infectious disease and different genotypes have been reported. This study aimed to investigate the genetic diversity and molecular epidemiology of TB in the lower northern region of Thailand, where genotyping data are limited.

METHODS

A total of 159 Mycobacterium tuberculosis complex (MTBC) isolates from this region were genotyped by spoligotyping and the major spoligotypes were further subdivided by the mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) method.

RESULTS

Spoligotyping identified 34 types and classified them into 14 clusters. East African-Indian (EAI) groups were the most frequent (44.7%), followed by Beijing (36.5%), with a higher prevalence of drug resistance. By 15-loci MIRU-VNTR typing, the major groups of the Beijing and EAI2_NTB were further differentiated into 44 and 21 subtypes forming 9 and 5 subclusters with cluster rates of 0.26 and 0.44, respectively. The Hunter-Gaston Discriminatory Index among the Beijing and EAI2_NTB groups were 0.987 and 0.931, respectively, indicating high diversity.

CONCLUSIONS

This is the first look at the MTBC genotypes in the lower northern region of Thailand, which could aid in understanding the distribution and potential spread of MTBC and Mycobacterium bovis in the target region to support TB control in Thailand.

Molecular determinants of multidrug-resistant tuberculosis in Sierra Leone

Multidrug-resistant tuberculosis (MDR-TB) management has become a serious global health challenge. Understanding its epidemic determinants on the regional level is crucial for developing effective control measures. We used whole genome sequencing data of 238 of Mycobacterium tuberculosis complex (MTBC) strains to determine drug resistance profiles, phylogeny, and transmission dynamics of MDR/rifampicin-resistant (RR) MTBC strains from Sierra Leone. Forty-two strains were classified as RR, 196 as MDR, 5 were resistant to bedaquiline (BDQ) and clofazimine (CFZ), but none was found to be resistant to fluoroquinolones. Sixty-one (26%) strains were resistant to all first-line drugs, three of which had additional resistance to BDQ/CFZ. The strains were classified into six major MTBC lineages (L), with strains of L4 being the most prevalent, 62% (n = 147), followed by L6 (Mycobacterium africanum) strains, (21%, n = 50). The overall clustering rate (using ≤d12 single-nucleotide polymorphism threshold) was 44%, stratified into 31 clusters ranging from 2 to 16 strains. The largest cluster (n = 16) was formed by sublineage 2.2.1 Beijing Ancestral 3 strains, which developed MDR several times. Meanwhile, 10 of the L6 strains had a primary MDR transmission. We observed a high diversity of drug resistance mutations, including borderline resistance mutations to isoniazid and rifampicin, and mutations were not detected by commercial assays. In conclusion, one in five strains investigated was resistant to all first-line drugs, three of which had evidence of BDQ/CFZ resistance. Implementation of interventions such as rapid diagnostics that prevent further resistance development and stop MDR-TB transmission chains in the country is urgently needed.

IMPORTANCE

A substantial proportion of MDR-TB strains in Sierra Leone were resistant against all first line drugs; however this makes the all-oral-six-month BPaLM regimen or other 6-9 months all oral regimens still viable, mainly because there was no FQ resistance.Resistance to BDQ was detected, as well as RR, due to mutations outside of the hotspot region. While the prevalence of those resistances was low, it is still cause for concern and needs to be closely monitored.

Parallel signatures of Mycobacterium tuberculosis and human Y-chromosome phylogeography support the Two Layer model of East Asian population history

The Two Layer hypothesis is fast becoming the favoured narrative describing East Asian population history. Under this model, hunter-gatherer groups who initially peopled East Asia via a route south of the Himalayas were assimilated by agriculturalist migrants who arrived via a northern route across Eurasia. A lack of ancient samples from tropical East Asia limits the resolution of this model. We consider insight afforded by patterns of variation within the human pathogen Mycobacterium tuberculosis (Mtb) by analysing its phylogeographic signatures jointly with the human Y-chromosome. We demonstrate the Y-chromosome lineages enriched in the traditionally hunter-gatherer groups associated with East Asia's first layer of peopling to display deep roots, low long-term effective population size, and diversity patterns consistent with a southern entry route. These characteristics mirror those of the evolutionarily ancient Mtb lineage 1. The remaining East Asian Y-chromosome lineage is almost entirely absent from traditionally hunter-gatherer groups and displays spatial and temporal characteristics which are incompatible with a southern entry route, and which link it to the development of agriculture in modern-day China. These characteristics mirror those of the evolutionarily modern Mtb lineage 2. This model paves the way for novel host-pathogen coevolutionary research hypotheses in East Asia.

The Global Success of Mycobacterium tuberculosis Modern Beijing Family Is Driven by a Few Recently Emerged Strains

Strains of the Mycobacterium tuberculosis complex (MTBC) Beijing family aroused concern because they were often found in clusters and appeared to be exceptionally transmissible. However, it was later found that strains of the Beijing family were heterogeneous, and the transmission advantage was restricted to sublineage L2.3 or modern Beijing. In this study, we analyzed the previously published genome sequences of 7,896 L2.3 strains from 51 different countries. Using BEAST software to approximate the temporal emergence of L2.3, our calculations suggest that L2.3 initially emerged in northern East Asia during the early 15th century and subsequently diverged into six phylogenetic clades, identified as L2.3.1 through L2.3.6. Using terminal branch length and genomic clustering as proxies for transmissibility, we found that the six clades displayed distinct population dynamics, with the three recently emerged clades (L2.3.4 to L2.3.6) exhibiting significantly higher transmissibility than the older three clades (L2.3.1 to L2.3.3). Of the Beijing family strains isolated outside East Asia, 83.1% belonged to the clades L2.3.4 to L2.3.6, which were also associated with more cross-border transmission. This work reveals the heterogeneity in sublineage L2.3 and demonstrates that the global success of Beijing family strains is driven by the three recently emerged L2.3 clades. IMPORTANCE The recent population dynamics of the global tuberculosis epidemic are heavily shaped by Mycobacterium tuberculosis complex (MTBC) strains with enhanced transmissibility. The infamous Beijing family strain stands out because it has rapidly spread throughout the world. Identifying the strains responsible for the global expansion and tracing their evolution should help to understand the nature of high transmissibility and develop effective strategies to control transmission. In this study, we found that the L2.3 sublineage diversified into six phylogenetic clades (L2.3.1 to L2.3.6) with various transmission characteristics. Clades L2.3.4 to L2.3.6 exhibited significantly higher transmissibility than clades L2.3.1 to L2.3.3, which helps explain why more than 80% of Beijing family strains collected outside East Asia belong to these three clades. We conclude that the global success of L2.3 was not caused by the entire L2.3 sublineage but rather was due to the rapid expansion of L2.3.4 to L2.3.6. Tracking the transmission of L2.3.4 to L2.3.6 strains can help to formulate targeted TB prevention and control.

Analysis of whiB7 in Mycobacterium tuberculosis reveals novel AT-hook deletion mutations

Mutations in whiB7 have been associated with both hypersusceptibility and resistance to various antibiotics in Mycobacterium tuberculosis (Mtb). Unlocking the secrets of antibiotic resistance in the bacterium, we examined mutations in the coding sequences of whiB7 of over 40,000 diverse Mtb isolates. Our results unveil the dominant c.191delG (Gly64delG) mutation, present in all members of the lineage L1.2.2 and its impact on WhiB7's conserved GVWGG-motif, causing conformational changes and deletion of the C-terminal AT-hook. Excitingly, we discovered six unique mutations associated with partial or total deletion of the AT-hook, specific to certain sublineages. Our findings suggest the selective pressures driving these mutations, underlining the potential of genomics to advance our understanding of Mtb's antibiotic resistance. As tuberculosis remains a global health threat, our study offers valuable insights into the diverse nature and functional consequences of whiB7 mutations, paving the way for the development of novel therapeutic interventions.

An overview of tuberculosis outbreaks reported in the years 2011-2020

BACKGROUND

In many countries tuberculosis (TB) remains a highly prevalent disease and a major contributor to infectious disease mortality. The fight against TB requires surveillance of the population of strains circulating worldwide and the analysis of the prevalence of certain strains in populations. Nowadays, whole genome sequencing (WGS) allows for accurate tracking of TB transmission. Currently, there is a lack of a comprehensive summary of the characteristics of TB outbreaks.

METHODS

We systematically analyzed studies reporting TB outbreaks worldwide, monitored through WGS of Mycobacterium tuberculosis. We 1) mapped the reported outbreaks from 2011- 2020, 2) estimated the average size of the outbreaks, 3) indicated genetic lineages causing the outbreaks, and 4) determined drug-resistance patterns of M. tuberculosis strains involved in the outbreaks.

RESULTS

Most data originated from Europe, Asia, and North America. We found that TB outbreaks were reported throughout the globe, on all continents, and in countries with both high and low incidences. The detected outbreaks contained a median of five M. tuberculosis isolates. Most strains causing the outbreaks belonged to lineage four, more rarely to lineage two. Reported outbreak isolates were often drug resistant.

CONCLUSIONS

We conclude that more WGS surveillance of M. tuberculosis outbreaks is needed. Globally standardized procedures might improve the control of M. tuberculosis infections.

Risk for Prison-to-Community Tuberculosis Transmission, Thailand, 2017-2020

To determine contributions of previously incarcerated persons to tuberculosis (TB) transmission in the community, we performed a healthcare facility-based cohort study of TB patients in Thailand during 2017-2020. We used whole-genome sequencing of Mycobacterium tuberculosis isolates from patients to identify genotypic clusters and assess the association between previous incarceration and TB transmission in the community. We identified 4 large genotype clusters (>10 TB patients/cluster); 28% (14/50) of the patients in those clusters were formerly incarcerated. Formerly incarcerated TB patients were more likely than nonincarcerated patients to be included in large clusters. TB patients within the large genotype clusters were geographically dispersed throughout Chiang Rai Province. Community TB transmission in the community was associated with the presence of formerly incarcerated individuals in Thailand. To reduce the risk for prison-to-community transmission, we recommend TB screening at the time of entry and exit from prisons and follow-up screening in the community.

Distribution and origins of Mycobacterium tuberculosis L4 in Southeast Asia

Molecular and genomic studies have revealed that Mycobacterium tuberculosis Lineage 4 (L4, Euro-American lineage) emerged in Europe before becoming distributed around the globe by trade routes, colonial migration and other historical connections. Although L4 accounts for tens or hundreds of thousands of tuberculosis (TB) cases in multiple Southeast Asian countries, phylogeographical studies have either focused on a single country or just included Southeast Asia as part of a global analysis. Therefore, we interrogated public genomic data to investigate the historical patterns underlying the distribution of L4 in Southeast Asia and surrounding countries. We downloaded 6037 genomes associated with 29 published studies, focusing on global analyses of L4 and Asian studies of M. tuberculosis. We identified 2256 L4 genomes including 968 from Asia. We show that 81 % of L4 in Thailand, 51 % of L4 in Vietnam and 9 % of L4 in Indonesia belong to sub-lineages of L4 that are rarely seen outside East and Southeast Asia (L4.2.2, L4.4.2 and L4.5). These sub-lineages have spread between East and Southeast Asian countries, with no recent European ancestor. Although there is considerable uncertainty about the exact direction and order of intra-Asian M. tuberculosis dispersal, due to differing sampling frames between countries, our analysis suggests that China may be the intermediate location between Europe and Southeast Asia for two of the three predominantly East and Southeast Asian L4 sub-lineages (L4.2.2 and L4.5). This new perspective on L4 in Southeast Asia raises the possibility of investigating host population-specific evolution and highlights the need for more structured sampling from Southeast Asian countries to provide more certainty of the historical and current routes of dispersal.

Distribution of Mycobacterium tuberculosis Lineages and Drug Resistance in Upper Myanmar

Mycobacterium tuberculosis complex (MTBC) is divided into 9 whole genome sequencing (WGS) lineages. Among them, lineages 1−4 are widely distributed. Multi-drug resistant tuberculosis (MDR-TB) is a major public health threat. For effective TB control, there is a need to obtain genetic information on lineages of Mycobacterium tuberculosis (Mtb) and to understand distribution of lineages and drug resistance. This study aimed to describe the distribution of major lineages and drug resistance patterns of Mtb in Upper Myanmar. This was a cross-sectional study conducted with 506 sequenced isolates. We found that the most common lineage was lineage 2 (n = 223, 44.1%). The most common drug resistance mutation found was streptomycin (n = 44, 8.7%). Lineage 2 showed a higher number of MDR-TB compared to other lineages. There were significant associations between lineages of Mtb and drug resistance patterns, and between lineages and geographical locations of Upper Myanmar (p value < 0.001). This information on the distribution of Mtb lineages across the geographical areas will support a lot for the better understanding of TB transmission and control in Myanmar and other neighboring countries. Therefore, closer collaboration in cross border tuberculosis control is recommended.

Host cell transcriptomic response to the multidrug-resistant Mycobacterium tuberculosis clonal outbreak Beijing strain reveals its pathogenic features

The upsurge of multidrug-resistant infections has rendered tuberculosis the principal cause of death among infectious diseases. A clonal outbreak multidrug-resistant triggering strain of Mycobacterium tuberculosis was identified in Kanchanaburi Province, labelled "MKR superspreader," which was found to subsequently spread to other regions, as revealed by prior epidemiological reports in Thailand. Herein, we showed that the MKR displayed a higher growth rate upon infection into host macrophages in comparison with the H37Rv reference strain. To further elucidate MKR's biology, we utilized RNA-Seq and differential gene expression analyses to identify host factors involved in the intracellular viability of the MKR. A set of host genes function in the cellular response to lipid pathway was found to be uniquely up-regulated in host macrophages infected with the MKR, but not those infected with H37Rv. Within this set of genes, the IL-36 cytokines which regulate host cell cholesterol metabolism and resistance against mycobacteria attracted our interest, as our previous study revealed that the MKR elevated genes associated with cholesterol breakdown during its growth inside host macrophages. Indeed, when comparing macrophages infected with the MKR to H37Rv-infected cells, our RNA-Seq data showed that the expression ratio of IL-36RN, the negative regulator of the IL-36 pathway, to that of IL-36G was greater in macrophages infected with the MKR. Furthermore, the MKR's intracellular survival and increased intracellular cholesterol level in the MKR-infected macrophages were diminished with decreased IL-36RN expression. Overall, our results indicated that IL-36RN could serve as a new target against this emerging multidrug-resistant M. tuberculosis strain.

Genome-Wide Study of Drug Resistant Mycobacterium tuberculosis and Its Intra-Host Evolution during Treatment

The emergence of drug resistant Mycobacterium tuberculosis (MTB) strains has become a global public health problem, while, at the same time, there has been development of new antimicrobial agents. The main goals of this study were to determine new variants associated with drug resistance in MTB and to observe which polymorphisms emerge in MTB genomes after anti-tuberculosis treatment. We performed whole-genome sequencing of 152 MTB isolates including 70 isolates as 32 series of pre- and post-treatment MTB. Based on genotypes and phenotypic drug susceptibility, we conducted phylogenetic convergence-based genome-wide association study (GWAS) with streptomycin-, isoniazid-, rifampicin-, ethambutol-, fluoroquinolones-, and aminoglycosides-resistant MTB against susceptible ones. GWAS revealed statistically significant associations of SNPs within Rv2820c, cyp123 and indels in Rv1269c, Rv1907c, Rv1883c, Rv2407, Rv3785 genes with resistant MTB phenotypes. Comparisons of serial isolates showed that treatment induced different patterns of intra-host evolution. We found indels within Rv1435c and ppsA that were not lineage-specific. In addition, Beijing-specific polymorphisms within Rv0036c, Rv0678, Rv3433c, and dop genes were detected in post-treatment isolates. The appearance of Rv3785 frameshift insertion in 2 post-treatment strains compared to pre-treatment was also observed. We propose that the insertion within Rv3785, which was a GWAS hit, might affect cell wall biosynthesis and probably mediates a compensatory mechanism in response to treatment. These results may shed light on the mechanisms of MTB adaptation to chemotherapy and drug resistance formation.

Emergence of multi-drug-resistant Mycobacterium tuberculosis in Niger: A snapshot based on whole-genome sequencing

Background

Among other West African countries experiencing the high endemicity of deadly tuberculosis, the situation in Niger is poorly evidenced by microbiological investigations.

Methodology/Principal findings

The study of 42 isolates of Mycobacterium tuberculosis from Niger by whole genome sequencing using Illumina iSeq technology yielded four M. tuberculosis lineages: Indo-Oceanic L1 (n = 1) (2.3%), East-Asian (n = 1) (2.3%), East-African Indian L3 (n = 2) (4.7%) and Euro-American L4 (n = 38) (90.4%). The sub-lineage L4.1.3 comprising 18 isolates (47.3%) was predominant, followed by the L4.6.2.2 sub-lineage (Cameroon genotype, n = 13 isolates) (34.2%). Investigating drug resistance profile for 12 antibiotics found 8/42 (19%) pan-susceptible isolates and 34/42 (81%) resistant isolates; with 40/42 (95.2%) isolates being susceptible to clofazimine-bedaquiline.

Conclusions/Significance

These unprecedented data from Niger highlight the dynamics of tuberculosis transmission and drug resistance in Niger and may assist tuberculosis control in this country which continues to support a high burden of tuberculosis.

Tuberculosis is a major public health problem in Niger, in West Africa. Niger has an emerging problem with multidrug-resistant tuberculosis (MDR-TB). Whole genome sequencing was used to understand the epidemiology of tuberculosis and genetics of multi-drug resistance among patients from the regions in Niger. In this study, most isolates of M. tuberculosis from this dataset belonged to the L4.6.2.2 sub-lineage and L4.1.3 sub-lineage within the Euro-American lineage. Thirty-four out of 42 (81%) isolates were detected as resistant isolates. Our study highlights the need for epidemiological surveillance and more concerted efforts to ensure that patients are put through treatment.

Snapshot of Mycobacterium tuberculosis Phylogenetics from an Indian State of Arunachal Pradesh Bordering China

Uncontrolled transmission of Mycobacterium tuberculosis (M. tuberculosis, MTB) drug resistant strains is a challenge to control efforts of the global tuberculosis program. Due to increasing multi-drug resistant (MDR) cases in Arunachal Pradesh, a northeastern state of India, the tracking and tracing of these resistant MTB strains is crucial for infection control and spread of drug resistance. This study aims to correlate the phenotypic DST, genomic DST (gDST) and phylogenetic analysis of MDR-MTB strains in the region. Of the total 200 samples 22 (11%) patients suspected of MDR-TB and 160 (80%) previously treated MDR-TB cases, 125 (62.5%) were identified as MTB. MGIT-960 SIRE DST detected 71/125 (56.8%) isolates as MDR/RR-MTB of which 22 (30.9%) were detected resistant to second-line drugs. Whole-genome sequencing of 65 isolates and their gDST found Ser315Thr mutation in katG (35/45; 77.8%) and Ser531Leu mutation in rpoB (21/41; 51.2%) associated with drug resistance. SNP barcoding categorized the dataset with Lineage2 (41; 63.1%) being predominant followed by Lineage3 (10; 15.4%), Lineage1 (8; 12.3%) and Lineage4 (6; 9.2%) respectively. Phylogenetic assignment by cgMLST gave insights of two Beijing sub-lineages viz; 2.2.1 (SNP difference < 19) and 2.2.1.2 (SNP difference < 9) associated with recent ongoing transmission in Arunachal Pradesh. This study provides insights in identifying two virulent Beijing sub-lineages (sub-lineage 2.2.1 and 2.2.1.2) with ongoing transmission of TB drug resistance in Arunachal Pradesh.

Snapshot of Mycobacterium tuberculosis Phylogenetics from an Indian State of Arunachal Pradesh Bordering China

Uncontrolled transmission of Mycobacterium tuberculosis (M. tuberculosis, MTB) drug resistant strains is a challenge to control efforts of the global tuberculosis program. Due to increasing multi-drug resistant (MDR) cases in Arunachal Pradesh, a northeastern state of India, the tracking and tracing of these resistant MTB strains is crucial for infection control and spread of drug resistance. This study aims to correlate the phenotypic DST, genomic DST (gDST) and phylogenetic analysis of MDR-MTB strains in the region. Of the total 200 samples 22 (11%) patients suspected of MDR-TB and 160 (80%) previously treated MDR-TB cases, 125 (62.5%) were identified as MTB. MGIT-960 SIRE DST detected 71/125 (56.8%) isolates as MDR/RR-MTB of which 22 (30.9%) were detected resistant to second-line drugs. Whole-genome sequencing of 65 isolates and their gDST found Ser315Thr mutation in katG (35/45; 77.8%) and Ser531Leu mutation in rpoB (21/41; 51.2%) associated with drug resistance. SNP barcoding categorized the dataset with Lineage2 (41; 63.1%) being predominant followed by Lineage3 (10; 15.4%), Lineage1 (8; 12.3%) and Lineage4 (6; 9.2%) respectively. Phylogenetic assignment by cgMLST gave insights of two Beijing sub-lineages viz; 2.2.1 (SNP difference < 19) and 2.2.1.2 (SNP difference < 9) associated with recent ongoing transmission in Arunachal Pradesh. This study provides insights in identifying two virulent Beijing sub-lineages (sub-lineage 2.2.1 and 2.2.1.2) with ongoing transmission of TB drug resistance in Arunachal Pradesh.

Snapshot of Mycobacterium tuberculosis Phylogenetics from an Indian State of Arunachal Pradesh Bordering China

Uncontrolled transmission of Mycobacterium tuberculosis (M. tuberculosis, MTB) drug resistant strains is a challenge to control efforts of the global tuberculosis program. Due to increasing multi-drug resistant (MDR) cases in Arunachal Pradesh, a northeastern state of India, the tracking and tracing of these resistant MTB strains is crucial for infection control and spread of drug resistance. This study aims to correlate the phenotypic DST, genomic DST (gDST) and phylogenetic analysis of MDR-MTB strains in the region. Of the total 200 samples 22 (11%) patients suspected of MDR-TB and 160 (80%) previously treated MDR-TB cases, 125 (62.5%) were identified as MTB. MGIT-960 SIRE DST detected 71/125 (56.8%) isolates as MDR/RR-MTB of which 22 (30.9%) were detected resistant to second-line drugs. Whole-genome sequencing of 65 isolates and their gDST found Ser315Thr mutation in katG (35/45; 77.8%) and Ser531Leu mutation in rpoB (21/41; 51.2%) associated with drug resistance. SNP barcoding categorized the dataset with Lineage2 (41; 63.1%) being predominant followed by Lineage3 (10; 15.4%), Lineage1 (8; 12.3%) and Lineage4 (6; 9.2%) respectively. Phylogenetic assignment by cgMLST gave insights of two Beijing sub-lineages viz; 2.2.1 (SNP difference < 19) and 2.2.1.2 (SNP difference < 9) associated with recent ongoing transmission in Arunachal Pradesh. This study provides insights in identifying two virulent Beijing sub-lineages (sub-lineage 2.2.1 and 2.2.1.2) with ongoing transmission of TB drug resistance in Arunachal Pradesh.

Whole-genome single nucleotide variant phylogenetic analysis of Mycobacterium tuberculosis Lineage 1 in endemic regions of Asia and Africa

Mycobacterium tuberculosis (Mtb) lineage 1 (L1) contributes considerably to the disease morbidity. While whole genome sequencing (WGS) is increasingly used for studying Mtb, our understanding of genetic diversity of L1 remains limited. Using phylogenetic analysis of WGS data from endemic range in Asia and Africa, we provide an improved genotyping scheme for L1. Mapping deletion patterns of the 68 direct variable repeats (DVRs) in the CRISPR region of the genome onto the phylogeny provided supporting evidence that the CRISPR region evolves primarily by deletion, and hinted at a possible Southeast Asian origin of L1. Both phylogeny and DVR patterns clarified some relationships between different spoligotypes, and highlighted the limited resolution of spoligotyping. We identified a diverse repertoire of drug resistance mutations. Altogether, this study demonstrates the usefulness of WGS data for understanding the genetic diversity of L1, with implications for public health surveillance and TB control. It also highlights the need for more WGS studies in high-burden but underexplored regions.

Connection between two historical tuberculosis outbreak sites in Japan, Honshu, by a new ancestral Mycobacterium tuberculosis L2 sublineage

By gathering 680 publicly available Sequence Read Archives from isolates of Mycobacterium tuberculosis complex (MTBC) including 190 belonging to the lineage 2 Beijing , and using an in-house bioinformatical pipeline, the TB-Annotator , that analyses more than 50 000 characters, we describe herein a new L2 sublineage from 20 isolates found in the Tochigi province, (Japan), that we designate as asia ancestral 5 (AAnc5). These isolates harbour a number of specific criteria (42 SNPs) and their intra-cluster pairwise distance suggests historical and not epidemiological transmission. These isolates harbour a mutation in rpoC , and do not fulfil, any of the modern Beijing lineage criteria, nor any of the other ancestral Beijing lineages described so far. Asia ancestral 5 isolates do not possess mutT2 58 and ogt 12 characteristics of modern Beijing , but possess ancestral Beijing SNPs characteristics. By looking into the literature, we found a reference isolate ID381, described in Kobe and Osaka belonging to the ‘G3’ group, sharing 36 out of the 42 specific SNPs found in AAnc5. We also assessed the intermediate position of the asia ancestral 4 (AAnc4) sublineage recently described in Thailand and propose an improved classification of the L2 that now includes AAnc4 and AAnc5. By increasing the recruitment into TB-Annotator to around 3000 genomes (including 642 belonging to L2), we confirmed our results and discovered additional historical ancestral L2 branches that remain to be investigated in more detail. We also present, in addition, some anthropological and historical data from Chinese and Japan history of tuberculosis, as well as from Korea, that could support our results on L2 evolution. This study shows that the reconstruction of the early history of tuberculosis in Asia is likely to reveal complex patterns since its emergence.

Genomic signatures of pre-resistance in Mycobacterium tuberculosis

Recent advances in bacterial whole-genome sequencing have resulted in a comprehensive catalog of antibiotic resistance genomic signatures in Mycobacterium tuberculosis. With a view to pre-empt the emergence of resistance, we hypothesized that pre-existing polymorphisms in susceptible genotypes (pre-resistance mutations) could increase the risk of becoming resistant in the future. We sequenced whole genomes from 3135 isolates sampled over a 17-year period. After reconstructing ancestral genomes on time-calibrated phylogenetic trees, we developed and applied a genome-wide survival analysis to determine the hazard of resistance acquisition. We demonstrate that M. tuberculosis lineage 2 has a higher risk of acquiring resistance than lineage 4, and estimate a higher hazard of rifampicin resistance evolution following isoniazid mono-resistance. Furthermore, we describe loci and genomic polymorphisms associated with a higher risk of resistance acquisition. Identifying markers of future antibiotic resistance could enable targeted therapy to prevent resistance emergence in M. tuberculosis and other pathogens.

Revised nomenclature and SNP barcode for Mycobacterium tuberculosis lineage 2

Mycobacterium tuberculosis (Mtb) lineage 2 (L2) strains are present globally, contributing to a widespread tuberculosis (TB) burden, particularly in Asia where both prevalence of TB and numbers of drug resistant TB are highest. The increasing availability of whole-genome sequencing (WGS) data worldwide provides an opportunity to improve our understanding of the global genetic diversity of Mtb L2 and its association with the disease epidemiology and pathogenesis. However, existing L2 sublineage classification schemes leave >20 % of the Modern Beijing isolates unclassified. Here, we present a revised SNP-based classification scheme of L2 in a genomic framework based on phylogenetic analysis of >4000 L2 isolates from 34 countries in Asia, Eastern Europe, Oceania and Africa. Our scheme consists of over 30 genotypes, many of which have not been described before. In particular, we propose six main genotypes of Modern Beijing strains, denoted L2.2.M1–L2.2.M6. We also provide SNP markers for genotyping L2 strains from WGS data. This fine-scale genotyping scheme, which can classify >98 % of the studied isolates, serves as a basis for more effective monitoring and reporting of transmission and outbreaks, as well as improving genotype-phenotype associations such as disease severity and drug resistance. This article contains data hosted by Microreact.

Whole-genome comparative analysis at the lineage/sublineage level discloses relationships between Mycobacterium tuberculosis genotype and clinical phenotype

Background

Human tuberculosis (TB) caused by members of the Mycobacterium tuberculosis complex (MTBC) is the main cause of death among infectious diseases worldwide. Pulmonary TB (PTB) is the most common clinical phenotype of the disease, but some patients develop an extrapulmonary (EPTB) phenotype in which any organ or tissue can be affected. MTBC species include nine phylogenetic lineages, with some appearing globally and others being geographically restricted. EPTB can or not have pulmonary involvement, challenging its diagnosis when lungs are not implicated, thus causing an inadequate treatment. Finding evidence of a specific M. tuberculosis genetic background associated with EPTB is epidemiologically relevant due to the virulent and multidrug-resistant strains isolated from such cases. Until now, the studies conducted to establish associations between M. tuberculosis lineages and PTB/EPTB phenotypes have shown inconsistent results, which are attributed to the strain predominance from specific M. tuberculosis lineages/sublineages in the samples analyzed and the use of low-resolution phylogenetic tools that have impaired sublineage discrimination abilities. The present work elucidates the relationships between the MTBC strain lineages/sublineages and the clinical phenotypes of the disease as well as the antibiotic resistance of the strains.

Methods

To avoid biases, we retrieved the raw genomic reads (RGRs) of all (n = 245) the M. tuberculosis strains worldwide causing EPTB available in databases and an equally representative sample of the RGRs (n = 245) of PTB strains. A multiple alignment was constructed, and a robust maximum likelihood phylogeny based on single-nucleotide polymorphisms was generated, allowing effective strain lineage/sublineage assignment.

Results

A significant Odds Ratio (OR range: 1.8–8.1) association was found between EPTB and the 1.1.1, 1.2.1, 4.1.2.1 and ancestral Beijing sublineages. Additionally, a significant association between PTB with 4.3.1, 4.3.3, and 4.5 and Asian African 2 and Europe/Russia B0/W148 modern Beijing sublineages was found. We also observed a significant association of Lineage 3 strains with multidrug resistance (OR 3.8; 95% CI [1.1–13.6]), as well as between modern Beijing sublineages and antibiotic resistance (OR 4.3; 3.8–8.6). In this work, it was found that intralineage diversity can drive differences in the immune response that triggers the PTB/EPTB phenotype.

Interaction analysis of Mycobacterium tuberculosis between the host environment and highly mutated genes from population genetic structure comparison

We aimed to investigate the genetic and demographic differences and interactions between areas where observed genomic variations in Mycobacterium tuberculosis (M. tb) were distributed uniformly in cold and hot spots.The cold and hot spot areas were identified using the reported incidence of TB over the previous 5 years. Whole genome sequencing was performed on 291 M. tb isolates between January and June 2018. Analysis of molecular variance and a multifactor dimensionality reduction (MDR) model was applied to test gene-gene-environment interactions. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were computed to test the extent to which genetic mutation affects the TB epidemic using a multivariate logistic regression model.The percentage of the Beijing family strain in hot spots was significantly higher than that in cold spots (64.63% vs 50.69%, P = .022), among the elderly, people with a low BMI, and those having a history of contact with a TB patient (all P < .05). Individuals from cold spot areas had a higher frequency of out-of-town traveling (P < .05). The mutation of Rv1186c, Rv3900c, Rv1508c, Rv0210, and an Intergenic Region (SNP site: 3847237) showed a significant difference between cold and hot spots. (P < .001). The MDR model displayed a clear negative interaction effect of age groups with BMI (interaction entropy: -3.55%) and mutation of Rv0210 (interaction entropy: -2.39%). Through the mutations of Rv0210 and BMI had a low independent effect (interaction entropy: -1.46%).Our data suggests a statistically significant role of age, BMI and the polymorphisms of Rv0210 genes in the transmission and development of M. tb. The results provide clues for the study of susceptibility genes of M. tb in different populations. The characteristic strains showed a local epidemic. Strengthening genotype monitoring of strains in various regions can be used as an early warning signal of epidemic spillover.

Distribution of molecular strains of Mycobacterium tuberculosis in an intermediate burden Asia Pacific city

Hong Kong is an intermediate tuberculosis (TB) burden city in Asia Pacific with slow decline of case notification in the last decade. By 24-loci mycobacterial interspersed repetitive units – variable number of tandem repeats genotyping, we examined 534 Mycobacterium tuberculosis isolates collected from culture-positive hospitalised TB patients in a 1.7 million population geographic region in the city. Overall, 286 (75%) were classified as Beijing genotype, of which 216 (76%) and 59 (21%) belonged to modern and ancient sub-lineage, respectively. Only two cases were genetically clustered while spatial clustering was absent. Male gender, permanent residency in Hong Kong and born in Hong Kong or Mainland China were associated with Beijing genotype. The high prevalence of Beijing modern lineage was similar to that in East Asia, which reflected the pattern resulting from population migration. The paucity of clustering suggested that reactivation accounted for most of the TB disease cases, which was and echoed by observation that half were 60 years old or above, and the presence of co-morbid medical conditions. The predominance of reactivation TB cases in intermediate burden localities implies that the detection and control of latent TB infection would be the major challenge in achieving TB elimination.

Estimation of the global burden of Mycobacterium tuberculosis lineage 1

Tuberculosis is still problematic as it affects large numbers of people globally. Mycobacterium tuberculosis Lineage 1 (L1) or Indo Oceanic Lineage, one of widespread major lineages, has a specific geographic distribution and high mortality. It is highly diverse and endemic in several high burden countries. However, studies on the global burden of L1 and its sublineages remain limited. This may lead to the underestimation of the importance of its variance in developing and applying tuberculosis control measures. This study aimed to estimate the number of patients infected with M. tuberculosis L1 and its sublineages worldwide. The proportion of L1 among tuberculosis patients was searched in published reports from countries around the world and the number of patients was calculated based on a WHO report on country incidences and populations. The numbers of patients infected with the five major sublineages, namely L1.1.1, L1.1.2, L1.1.3, L1.2.1, and L1.2.2 were estimated where information was available. It was found that L1 accounted for 28% of global tuberculosis cases in 2012 and 2018. Over 80% of the L1 global burden was in India, the Philippines, Indonesia and Bangladesh, which are also among the countries with highest absolute numbers of tuberculosis patients in the world. Globally, the estimated number of patients infected with M. tuberculosis L1.2.1 and L1.1.2 was over 1.1 million and of patients infected with L1.1.1 was about 200,000. This study demonstrated that L1 contributes significantly to the global burden of tuberculosis. To achieve the End TB Strategy, more attention needs to be paid to the responses of M. tuberculosis L1 to various control measures.

Identification and in silico functional prediction of lineage-specific SNPs distributed in DosR-related proteins and resuscitation-promoting factor proteins of Mycobacterium tuberculosis

One-third of the world population is infected by Mycobacterium tuberculosis, which may persist in the latent or dormant state. Bacteria can shift to dormancy when encountering harsh conditions such as low oxygen, nutrient starvation, high acidity and host immune defenses. Genes related to the dormancy survival regulator (DosR) regulon are responsible for the inhibition of aerobic respiration and replication, which is required to enter dormancy. Conversely, resuscitation-promoting factor (rpf) proteins participate in reactivation from dormancy and the development of active tuberculosis (TB). Many DosR regulon and rpf proteins are immunodominant T cell antigens that are highly expressed in latent TB infection. They could serve as TB vaccine candidates and be used for diagnostic development. We explored the genetic polymorphisms of 50 DosR-related genes and 5 rpf genes among 1,170 previously sequenced clinical M. tuberculosis genomes. Forty-three lineage- or sublineage-specific nonsynonymous single nucleotide polymorphisms (nsSNPs) were identified. Ten nsSNPs were specific to all Mtb isolates belonging to lineage 1 (L1). Two common sublineages, the Beijing family (L2.2) and EAI2 (L1.2.1), differed at as many as 26 lineage- or sublineage-specific SNPs. DosR regulon genes related to membrane proteins and the rpf family possessed mean dN/dS ratios greater than one, suggesting that they are under positive selection. Although the T cell epitope regions of DosR-related and rpf antigens were quite conserved, we found that the epitopes in L1 had higher rates of genetic polymorphisms than the other lineages. Some mutations in immunogenic epitopes of the antigens were specific to particular M. tuberculosis lineages. Therefore, the genetic diversity of the DosR regulon and rpf proteins might impact the adaptation of M. tuberculosis to the dormant state and the immunogenicity of latency antigens, which warrants further investigation.

Genomic evidence supporting the clonal expansion of extensively drug-resistant tuberculosis bacteria belonging to a rare protoBeijing genotype

Tuberculosis disease (TB), caused by Mycobacterium tuberculosis, is a major public health issue in Thailand. The high prevalence of modern Beijing (Lineage 2.2.1) strains has been associated with multi- and extensively drug-resistant infections (MDR-, XDR-TB), complicating disease control. The impact of rarer proto-Beijing (L2.1) strains is less clear. In our study of thirty-seven L2.1 clinical isolates spanning thirteen years, we found a high prevalence of XDR-TB cases (32.4%). With ≤ 12 pairwise SNP distances, 43.2% of L2.1 patients belong to MDR-TB or XDR-TB transmission clusters suggesting a high level of clonal expansion across four Thai provinces. All XDR-TB (100%) were likely due to transmission rather than inadequate treatment. We found a 47 mutation signature and a partial deletion of the fadD14 gene in the circulating XDR-TB cluster, which can be used for surveillance of this rare and resilient M. tuberculosis strain-type that is causing increasing health burden. We also detected three novel deletion positions, a deletion of 1285 bp within desA3 (Rv3230c), large deletions in the plcB, plcA, and ppe38 gene which may play a role in the virulence, pathogenesis or evolution of the L2.1 strain-type.

Ubiquitous and multifaceted: SIT53 spoligotype does not correlate with any particular family of Mycobacterium tuberculosis

Euro-American lineage (Lineage 4) of Mycobacterium tuberculosis comprises genetically and geographically diverse families that differ in their clinical and/or epidemiological capacities. Due to the characteristic structure of the CRISPR locus (presence of almost all 43 classical spacers except for deleted signals 33-36), spoligotype SIT53 takes the basal position in the evolution of this lineage. In the SITVIT database, it is assigned to the "ill-defined" T family and T1 subfamily. Here, I analyzed the phylogenetic diversity of SIT53 isolates and discussed interconnected terminological issues concerning M. tuberculosis population structure. The 24-MIRU-VNTR profiles of 266 SIT53 isolates from Europe, Asia, Africa, and South America were submitted to the phylogenetic analysis jointly with reference profiles of different families from MIRU-VNTRplus database. Under this analysis, SIT53 isolates were clustered within different and distant families such as Ghana, NEW-1 (L4.5), TUR (L4.2.2.1), etc whereas many remained unclassified within L4. This confirms the evolutionarily basal position of this spoligotype and in its turn, this demonstrates that SIT53 does not correspond to any particular family of M. tuberculosis. Instead, different SIT53 subpopulations with evolutionarily stable and unchanged CRISPR locus gave rise to different and distant families that in many instances evolved through long-term allopatric evolution.

Geno-Spatial Distribution of Mycobacterium Tuberculosis and Drug Resistance Profiles in Myanmar-Thai Border Area

Worldwide, studies investigating the relationship between the lineage of Mycobacterium tuberculosis (MTB) across geographic areas has empowered the “End TB” program and understand transmission across national boundaries. Genomic diversity of MTB varies with geographical locations and ethnicity. Genomic diversity can also affect the emergence of drug resistance. In Myanmar, we still have limited genetic information about geographical, ethnicity, and drug resistance linkage to MTB genetic information. This study aimed to describe the geno-spatial distribution of MTB and drug resistance profiles in Myanmar–Thailand border areas. A cross-sectional study was conducted with a total of 109 sequenced isolates. The lineages of MTB and the potential associated socio-demographic, geographic and clinical factors were analyzed using Fisher’s exact tests. p value of statistically significance was set at < 0.05. We found that 67% of the isolates were lineage 1 (L1)/East-African-Indian (EAI) (n = 73), followed by lineage 2 (L2)/Beijing (n = 26), lineage 4 (L4)/European American (n = 6) and lineage 3 (L3)/Delhi/Central Asian (n = 4). “Gender”, “type of TB patient”, “sputum smear grading” and “streptomycin resistance” were significantly different with the lineages of MTB. Sublineages of L1, which had never been reported elsewhere in Myanmar, were detected in this study area. Moreover, both ethnicity and lineage of MTB significantly differed in distribution by patient location. Diversity of the lineage of MTB and detection of new sublineages suggested that this small area had been resided by a heterogeneous population group who actively transmitted the disease. This information on distribution of lineage of MTB can be linked in the future with those on the other side of the border to evaluate cross-border transmission.

24-locus MIRU-VNTR and Spoligotyping analysis of drug-resistant Mycobacterium tuberculosis strains isolated from Northeastern Thailand

Tuberculosis, caused by Mycobacterium tuberculosis (MTB) infection, remains a global health problem with increased concerns due to drug-resistant tuberculosis. However, molecular genotyping profiles may give insight of the transmission of TB in a particular region. The present study aimed to characterize the genetic diversity of drug-resistant MTB and evaluate primer sets applied for the epidemiological study of circulating MTB in Northeastern Thailand. A total of 92 MTB isolates, resistant to rifampicin and/or isoniazid, were collected from the Office of Disease Prevention and Control between 2013 and 2016. All isolates were genotyped by 24-locus MIRU-VNTR typing combined with spoligotyping. We also analyzed the distributions of drug susceptibility pattern and demographic data among different genotypes. In comparison with different loci sets, discriminatory power based on 12, 15, 24 standard primers were investigated. Eighty-six particular profiles were found; among the patterns, two clusters were produced in 8 strains. East African Indians (EAI) were the most prevalent strains (33 isolates, 35.87%) followed by Beijing (30 isolates, 32.61%), with 23 unknown isolates strains also found. The HGDI based on combination of 24 loci analysis and spoligotyping was 0.9962. The number of tandem repeat generated was highly discriminant (HGDI>0.6) at locus 580 (0.66), 960 (0.67), 2163b (0.73), 2165 (0.62), 2461 (0.68) 3690 (0.73) and 4052 (0.79), respectively. In contrast, the diversity at locus 154 and 2059 was not revealed. The results emphasized that 24-locus MIRU-VNTR and spoligotyping could be useful for epidemiological surveillance of drug-resistant MTB in this region. At a given allelic diversity, 7 primer sets containing MIRU04, MIRU10, QUB2163b, ETRA, ETRB, Mtub39 and QUB26 may be considered for screening the VNTR patterns. In addition, this study gathered both demographics and genotypic data within the same investigation for further tuberculosis prevention and control.

The geno-spatio analysis of Mycobacterium tuberculosis complex in hot and cold spots of Guangxi, China

BACKGROUND

At present, there are few studies on polymorphism of Mycobacterium tuberculosis (Mtb) gene and how it affects the TB epidemic. This study aimed to document the differences of polymorphisms between tuberculosis hot and cold spot areas of Guangxi Zhuang Autonomous Region, China.

METHODS

The cold and hot spot areas, each with 3 counties, had been pre-identified by TB incidence for 5 years from the surveillance database. Whole genome sequencing analysis was performed on all sputum Mtb isolates from the detected cases during January and June 2018. Single nucleotide polymorphism (SNP) of each isolate compared to the H37Rv strain were called and used for lineage and sub-lineage identification. Pairwise SNP differences between every pair of isolates were computed. Analyses of Molecular Variance (AMOVA) across counties of the same hot or cold spot area and between the two areas were performed.

RESULTS

As a whole, 59.8% (57.7% sub-lineage 2.2 and 2.1% sub-lineage 2.1) and 39.8% (17.8% sub-lineage 4.4, 6.5% sub-lineage 4.2 and 15.5% sub-lineage 4.5) of the Mtb strains were Lineage 2 and Lineage 4 respectively. The percentages of sub-lineage 2.2 (Beijing family strains) are significantly higher in hot spots. Through the MDS dimension reduction, the genomic population structure in the three hot spot counties is significantly different from those three cold spot counties (T-test p = 0.05). The median of SNPs distances among Mtb isolates in cold spots was greater than that in hot spots (897 vs 746, Rank-sum test p < 0.001). Three genomic clusters, each with genomic distance ≤12 SNPs, were identified with 2, 3 and 4 consanguineous strains. Two clusters were from hot spots and one was from cold spots.

CONCLUSION

Narrower genotype diversity in the hot area may indicate higher transmissibility of the Mtb strains in the area compared to those in the cold spot area.

Genomic signatures of drug resistance in highly resistant Mycobacterium tuberculosis strains of the early ancient sublineage of Beijing genotype in Russia

The Mycobacterium tuberculosis Beijing genotype is a clinically and epidemiologically important lineage that is subdivided into ancient/ancestral and modern strains. In our previous study in western Siberia, we identified variable number of tandem repeats (VNTR)-based clusters within the early ancient sublineage of the Beijing genotype characterized by an unexpectedly high rate of extensive drug resistance (XDR). In the current study, next generation sequencing data were analysed to gain insight into genomic signatures underlying drug resistance of these strains. A total of 184 genomes of the Beijing early ancient sublineage from Russia (16), China (15), Japan (36), Korea (25), Vietnam (18), Thailand (73), and the USA (1) were used for phylogenetic analysis. The drug-resistant profile was deduced genotypically. The Russian isolates were distributed into two clusters and were all drug resistant, mainly pre-XDR and XDR. The largest of these clusters included only Russian isolates from remote locations in both Asian and European parts of the country. All its isolates had a quadruple drug resistance (to isoniazid, rifampin, ethambutol and streptomycin) due to the 6-mutation signature (KatG Ser315Thr, KatG Ile335Val, RpoB Ser450Leu, RpoC Asp485Asn, EmbB Gln497Arg, and RpsL Lys43Arg). In most samples, it was complemented with additional and different pncA, gyrA and rrs mutations leading to the pre-XDR/XDR genotype. Phylogenomic analysis indicates a distant origin of this Russian resistant cluster in the early 1970s but location and circumstances are yet to be clarified.

Homoplastic single nucleotide polymorphisms contributed to phenotypic diversity in Mycobacterium tuberculosis

Homoplastic mutations are mutations independently occurring in different clades of an organism. The homoplastic changes may be a result of convergence evolution due to selective pressures. Reports on the analysis of homoplastic mutations in Mycobacterium tuberculosis have been limited. Here we characterized the distribution of homoplastic single nucleotide polymorphisms (SNPs) among genomes of 1,170 clinical M. tuberculosis isolates. They were present in all functional categories of genes, with pe/ppe gene family having the highest ratio of homoplastic SNPs compared to the total SNPs identified in the same functional category. Among the pe/ppe genes, the homoplastic SNPs were common in a relatively small number of homologous genes, including ppe18, the protein of which is a component of a promising candidate vaccine, M72/AS01E. The homoplastic SNPs in ppe18 were particularly common among M. tuberculosis Lineage 1 isolates, suggesting the need for caution in extrapolating the results of the vaccine trial to the population where L1 is endemic in Asia. As expected, homoplastic SNPs strongly associated with drug resistance. Most of these mutations are already well known. However, a number of novel mutations associated with streptomycin resistance were identified, which warrants further investigation. A SNP in the intergenic region upstream of Rv0079 (DATIN) was experimentally shown to increase transcriptional activity of the downstream gene, suggesting that intergenic homoplastic SNPs should have effects on the physiology of the bacterial cells. Our study highlights the potential of homoplastic mutations to produce phenotypic changes. Under selective pressure and during interaction with the host, homoplastic mutations may confer advantages to M. tuberculosis and deserve further characterization.

Genetic profiling of Mycobacterium tuberculosis revealed "modern" Beijing strains linked to MDR-TB from Southwestern Colombia

Beijing strains of Mycobacterium tuberculosis (lineage 2) have been associated with drug-resistance and transmission of tuberculosis worldwide. Most of the Beijing strains identified in the Colombian Pacific coast have exhibited a multidrug resistant (MDR) phenotype. We sought to evaluate the clonality and sublineage of Beijing strains circulating in Southwestern Colombia. Thirty-seven Beijing strains were identified through spoligotyping out of 311 clinical isolates collected in 9 years from 2002-2010. Further analysis by MIRU-VNTR 24 loci was conducted for the Beijing strains. For sublineage classification, deletions of RD105, RD207, and RD131 and point mutations at fbpB, mutT2, and acs were evaluated. Drug-resistance associated mutations to first- and second-line anti-TB drugs were also evaluated. Additionally, two Beijing strains were Illumina-whole genome sequenced (one MDR and one drug-susceptible). Among the 37 Beijing strains characterized, 36 belonged to the SIT190 type from which 28 were MDR, four pre-extensively drug resistant (XDR) TB, and four XDR-TB. The remaining strain was SIT1 and drug susceptible. MIRU-VNTR analysis allowed the identification of three Beijing clusters and two unique strains. Beijing strains were confirmed as "modern" sublineage. The mutations rpoB S531L and katG S315T were the most common among MDR strains. Moreover, the two strains evaluated by whole genome sequencing (WGS) shared most of the genetic features with the sublineage 2.2.1 "modern" Beijing previously characterized from Asian strains. WGS analysis of the MDR strain revealed the presence of eight SNPs previously reported in other MDR "Beijing-like" strains from Colombia. The presence of "modern" Beijing strains in Southwestern Colombia, most of them with MDR phenotype, suggests a different origin of this M. tuberculosis sublineage compared to other Beijing strains found in neighboring South American countries. This work may serve as a genetic baseline to study the evolution and spread of M. tuberculosis Beijing strains in Colombia, which play an important role in the propagation of MDR-TB.