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Burgos JS (General Directorate of Research and Healthcare Supervision, Department of Health, Valencia Government, Valencia, Spain); Meneu de Guillerna R (Vice-President Foundation Research Institute in Public Services, Valencia, Spain); Vanaclocha Luna H (General Directorate of Public Health, Department of Health, Valencia Government, Valencia, Spain); Burks DJ (The Prince Felipe Research Center-CIPF-, Valencia, Spain; Cervantes A (INCLIVA Health Research Institute, Valencia, Spain); Comas I (Biomedicine Institute of Valencia, Spanish Research Council (CSIC); Díez-Domingo J (Foundation for the promotion of health and biomedical research of the Valencian Community-FISABIO-, Valencia, Spain); Peiro S (Foundation for the promotion of health and biomedical research of the Valencian Community-FISABIO-, Valencia, Spain); González-Candelas F (CIBER in Epidemiology and Public Health, Spain; Joint Research Unit "Infection and Public Health" FISABIO-University of Valencia, Valencia, Spain; Institute for Integrative Systems Biology (I2SysBio), CSIC-University of Valencia, Valencia, Spain); Ferrer Albiach C (Fundación Hospital Provincial de Castelló); Hernández-Aguado I (University Miguel Hernández, Alicante, Spain); Oliver Ramírez N (DataPop Alliance); Sánchez-Payá J (Preventive Medicine Service, Alicante General and University Hospital, Alicante, Spain; Alicante Institute of Health and Biomedical Research (ISABIAL), Alicante, Spain; Vento Torres M (Instituto de Investigación Sanitaria La Fe); Zapater Latorre E (Fundación Hospital General Universitario de València); Navarro D (Microbiology Service, Clinic University Hospital, INCLIVA Health Research Institute, Valencia, Spain;Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain).

Wastewater-based epidemiology (WBE) has proven to be an effective tool for epidemiological surveillance of SARS-CoV-2 during the current COVID-19 pandemic. Furthermore, combining WBE together with high-throughput sequencing techniques can be useful for the analysis of SARS-CoV-2 viral diversity present in a given sample. The present study focuses on the genomic analysis of SARS-CoV-2 in 76 sewage samples collected during the three epidemiological waves that occurred in Spain from 14 wastewater treatment plants distributed throughout the country. The results obtained demonstrate that the metagenomic analysis of SARS-CoV-2 in wastewater allows the detection of mutations that define the B.1.1.7 lineage and the ability of the technique to anticipate the detection of certain mutations before they are detected in clinical samples. The study proves the usefulness of sewage sequencing to track Variants of Concern that can complement clinical testing to help in decision-making and in the analysis of the evolution of the pandemic.

A third Comirnaty vaccine dose increased SARS-CoV-2-receptor binding domain antibody levels (median of 93-fold) and neutralizing antibody titers against Wuhan-Hu-1 (median, 57-fold), Beta (median, 22-fold), Delta, (median, 43-fold) and Omicron (median, 8-fold) variants, particularly in SARS-CoV-2-naive individuals, but had a negligible impact on S-reactive T-cell immunity in nursing home residents. © The Author(s) 2022. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant breakthrough infections in nursing home residents following vaccination with Comirnaty (R) COVID-19 vaccine were characterized. In total, 201 participants (median age, 87 years; range, 64-100; 133 female) from two nursing homes in the Valencian community (Spain) were included. SARS-CoV-2-Spike (S) antibody responses were determined by a lateral flow immunocromatography (LFIC) assay and by quantitative electrochemiluminescent assay in LFIC-negative participants. SARS-CoV-2-S-IFN gamma T cells were enumerated by flow cytometry in 10 participants. Nasopharyngeal SARS-CoV-2 RNA loads were quantified by real-time polymerase chain reaction assays. Vaccine breakthrough COVID-19 due to the Delta variant occurred in 39 residents (median age, 87 years; range, 69-96; 31 female) at a median of 6.5 months after vaccination (nine requiring hospitalization). Breakthrough infections occurred at a higher rate (p < 0.0001) in residents who had not been previously infected with SARS-CoV-2 (naive) (33/108; 18%) than in those with prior diagnosis of SARS-CoV-2 infection (experienced) (6/93; 6.4%), and were more likely (p < 0.0001) to develop in residents who tested negative by LFIC (20/49) at 3 months after vaccination as compared to their LFIC-positive counterparts (19/142). Among LFIC-negative residents, a trend towards lower plasma anti-RBD antibody levels was noticed in those developing breakthrough infection (p = 0.16). SARS-CoV-2 RNA loads in nasopharyngeal specimens were lower in SARS-CoV-2-experienced residents (p < 0.001) and in those testing positive by LFIC (p = 0.13). The frequency of SARS-CoV-2-S-reactive T cells at 3 months was similar in LFIC-negative residents with (n = 7) or without (n = 3) breakthrough infection. Prior history of SARS-CoV-2 infection and detection of S-reactive antibodies by LFIC at 3 months is associated with a lower risk of Delta-variant breakthrough infection in nursing home residents at midterm after Comirnaty (R) COVID-19 vaccination.

Plots of all pN, pS and pN/pS trajectories calculated for the complete MTBC genome, for the antigen-epitope pairs (MTBC wide) and also for the antigen-epitope pairs but splitted by the main MTBC phylogenetic lineages (L1, L2, L3, L4, L5, L6, L7 and the animal-adapted strains). This dataset correspond to Dataset S7 in the publication Gene Evolutionary Trajectories in M. tuberculosis Reveal Temporal Signs of Selection, accepted in PNAS in february 2022.

Studies investigating the cumulative incidence of and immune status against SARS-CoV-2 infection provide valuable information for shaping public health decision-making. A cross-sectional study on 935 participants, conducted in the Valencian Community (VC), measuring anti-SARS-CoV-2-Receptor Binding Domain-RBD-total antibodies and anti-Nucleocapsid (N)-IgGs via electrochemiluminescence assays. Quantitation of neutralizing antibodies (NtAb) against ancestral and Omicron BA.1 and BA.2 variants and enumeration of SARS-CoV-2-S specific-IFN?-producing CD4(+) and CD8(+) T cells was performed in 100 and 137 participants, respectively. The weighted cumulative incidence was 51.9% (95% CI: 48.7-55.1) and was inversely related to age. Anti-RBD total antibodies were detected in 97% of participants; vaccinated and SARS-CoV-2-experienced (VAC-ex; n=442) presented higher levels (P

A third Comirnaty® vaccine dose increased SARS-CoV-2-receptor binding domain antibody levels (median of 93-fold) and neutralizing antibody titers against Wuhan-Hu-1 (median, 57-fold), Beta (median, 22-fold), Delta, (median, 43-fold) and Omicron (median, 8-fold) variants, particularly in SARS-CoV-2-naïve individuals, but had a negligible impact on S-reactive T-cell immunity in nursing home residents.

We investigated whether peripheral blood levels of SARS-CoV-2 Spike (5) receptor binding domain antibodies (anti-RBD), neutralizing antibodies (NtAb) targeting Omicron S, and S-reactive-interferon (IFN)-gamma-producing CD4(+) and CD8(+) T cells measured after a homologous booster dose (3D) with the Comirnaty (R) vaccine was associated with the likelihood of subsequent breakthrough infections due to the Omicron variant. An observational study including 146 nursing home residents (median age, 80 years; range, 66-99; 109 female) evaluated for an immunological response after 3D (at a median of 16 days). Anti-RBD total antibodies were measured by chemiluminescent immunoassay. NtAb were quantified by an Omicron S pseudotyped virus neutralization assay. SARS-CoV-2-S specific-IFN gamma-producing CD4(+) and CD8(+) T cells were enumerated by whole-blood flow cytometry for intracellular cytokine staining. In total, 33/146 participants contracted breakthrough Omicron infection (symptomatic in 30/33) within 4 months after 3D. Anti-RBD antibody levels were comparable in infected and uninfected participants (21 123 vs. 24 723 BAU/ml; p = 0.34). Likewise, NtAb titers (reciprocal IC50 titer, 157 vs. 95; p = 0.32) and frequency of virus-reactive CD4(+) (p = 0.82) and CD8(+) (p = 0.91) T cells were similar across participants in both groups. anti-RBD antibody levels and NtAb titers estimated at around the time of infection were also comparable (3445 vs. 4345 BAU/ml; p = 0.59 and 188.5 vs. 88.9; p = 0.70, respectively). Having detectable NtAb against Omicron or SARS-CoV-2-S-reactive-IFN gamma-producing CD4(+) or CD8(+) T cells after 3D was not correlated with increased protection from breakthrough infection (OR, 1.50; p = 0.54; OR, 0.0; p = 0.99 and OR 3.70; p = 0.23, respectively). None of the immune parameters evaluated herein, including NtAb titers against the Omicron variant, may reliably predict at the individual level the risk of contracting COVID-19 due to the Omicron variant in nursing home residents.

Burgos JS (General Directorate of Research and Healthcare Supervision, Department of Health, Valencia Government, Valencia, Spain); Meneu de Guillerna R (Vice-President Foundation Research Institute in Public Services, Valencia, Spain); Vanaclocha Luna H (General Directorate of Public Health, Department of Health, Valencia Government, Valencia, Spain); Burks DJ (The Prince Felipe Research Center-CIPF-, Valencia, Spain; Cervantes A (INCLIVA Health Research Institute, Valencia, Spain); Comas I (Biomedicine Institute of Valencia, Spanish Research Council (CSIC); Diez-Domingo J (Foundation for the promotion of health and biomedical research of the Valencian Community-FISABIO-, Valencia, Spain); Peiro S (Foundation for the promotion of health and biomedical research of the Valencian Community-FISABIO-, Valencia, Spain); Gonzalez-Candelas F (CIBER in Epidemiology and Public Health, Spain; Joint Research Unit "Infection and Public Health" FISABIO-University of Valencia, Valencia, Spain; Institute for Integrative Systems Biology (I2SysBio), CSIC-University of Valencia, Valencia, Spain); Ferrer Albiach C (Fundacion Hospital Provincial de Castello); Hernandez-Aguado I (University Miguel Hernandez, Alicante, Spain); Oliver Ramirez N (DataPop Alliance); Sanchez-Paya J (Preventive Medicine Service, Alicante General and University Hospital, Alicante, Spain; Alicante Institute of Health and Biomedical Research (ISABIAL), Alicante, Spain; Vento Torres M (Instituto de Investigacion Sanitaria La Fe); Zapater Latorre E (Fundacion Hospital General Universitario de Valencia); Navarro D (Microbiology Service, Clinic University Hospital, INCLIVA Health Research Institute, Valencia, Spain;Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain). Copyright © 2022 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Genomic studies of the Mycobacterium tuberculosis complex (MTBC) might shed light on the dynamics of its transmission, especially in high-burden settings, where recent outbreaks are embedded in the complex natural history of the disease. To this end, we conducted a 1 year prospective surveillance-based study in Mozambique. We applied whole-genome sequencing (WGS) to 295 positive cultures. We fully characterized MTBC isolates by phylogenetics and dating evaluation, and carried out a molecular epidemiology analysis to investigate further associations with pre-defined transmission risk factors. The majority of strains (49.5%, 136/275) belonged to lineage (L) 4; 57.8 % of them (159/275) were in genomic transmission clusters (cut-off 5 SNPs), and a strikingly high proportion (45.5%) shared an identical genotype (0 SNP pairwise distance). We found two 'likely endemic' clades, comprising 67 strains, belonging to L1.2, which dated back to the late 19th century and were associated with recent spread among people living with human immunodeficiency virus (PLHIV). We describe for the first time the population structure of MTBC in our region, a high tuberculosis (TB)/HIV burden area. Clustering analysis revealed an unforeseen pattern of spread and high rates of progression to active TB, suggesting weaknesses in TB control activities. The long-term presence of local strains in Mozambique, which were responsible for large transmission among HIV/TB-coinfected patients, calls into question the role of HIV in TB transmission.

A third Comirnaty vaccine dose increased severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor-binding domain antibody levels (median, 93-fold) and neutralizing antibody titers against Wuhan-Hu-1 (median, 57-fold), Beta (me 22-fold), Delta, (median, 43-fold), and Omicron (median, 8-fold) variants, but had less impact on S-reactive T-cell immunity in nursing home residents.

The coronavirus disease 2019 (COVID-19) pandemic has affected the world radically since 2020. Spain was one of the European countries with the highest incidence during the first wave. As a part of a consortium to monitor and study the evolution of the epidemic, we sequenced 2,170 samples, diagnosed mostly before lockdown measures. Here, we identified at least 500 introductions from multiple international sources and documented the early rise of two dominant Spanish epidemic clades (SECs), probably amplified by superspreading events. Both SECs were related closely to the initial Asian variants of SARS-CoV-2 and spread widely across Spain. We inferred a substantial reduction in the effective reproductive number of both SECs due to public-health interventions (R-e < 1), also reflected in the replacement of SECs by a new variant over the summer of 2020. In summary, we reveal a notable difference in the initial genetic makeup of SARS-CoV-2 in Spain compared with other European countries and show evidence to support the effectiveness of lockdown measures in controlling virus spread, even for the most successful genetic variants. Analysis of 2,170 SARS-CoV-2 sequences from the first wave of the COVID-19 epidemic in Spain provides insights into transmission patterns and the effects of lockdown on the emergence of new variants.

Background: Growing international migration has increased the complexity of tuberculosis transmission patterns. Italy's decision to close its borders in 2018 made of Spain the new European porte entree for migration from the Horn of Africa (HA). In one of the first rescues of migrants from this region at the end of 2018, tuberculosis was diagnosed in eight subjects, mainly unaccompanied minors. Methods: Mycobacterium tuberculosis isolates from these recently arrived migrants were analysed by Mycobacterial Interspersed Repetitive-Unit/Variable-Number of Tandem Repeat (MIRU-VNTR) and subsequent whole genome sequencing (WGS) analysis. Data were compared with those from collections from other European countries receiving migrants from the HA and a strain-specific PCR was applied for a fast searching of common strains. Infections in a cellular model were performed to assess strain virulence. Results: MIRU-VNTR analysis allowed identifying an epidemiological cluster involving three of the eight cases from Somalia (0 single-nucleotide polymorphisms between isolates, HA cluster). Following detailed interviews revealed that two of these cases had shared the same migratory route in most of the trip and had spent a long time at a detention camp in Libya. To confirm potential en route transmission for the three cases, we searched the same strain in collections from other European countries receiving migrants from the HA. MIRU-VNTR, WGS and a strainspecific PCR for the HA strain were applied. The same strain was identified in 12 cases from Eritrea diagnosed soon after their arrival in 2018 to the Netherlands, Belgium and Italy. Intracellular replication rate of the strain did not reveal abnormal virulence. Conclusions: Our study suggests a potential en route transmission of a pan-susceptible strain, which caused at least 15 tuberculosis cases in Somalian and Eritrean migrants diagnosed in four different European countries.

Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail(3-5). Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant's success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes.

Costa Rica has a low incidence of tuberculosis. Thus, identifying transmission hotspots is key to implement interventions. A tuberculosis outbreak was suspected in a prison in Costa Rica. Given the suboptimal quality of the samples received in our laboratory in Madrid, we applied alternative schemes for their analysis. In the first scheme, we bypassed the standard approach of applying systematic mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) and used a strain-specific polymerase chain reaction (PCR) that allowed identifying a cluster involving six cases (C1). The second scheme followed the canonical MIRU-VNTR path coupled with a whole-genomic amplification step, by which a second unsuspected overlapping cluster (C2), was detected in the same prison. These findings justified the implementation of a surveillance programme adapted to local resources based on a tailored multiplex allele-specific oligonucleotide (ASO)-PCR targeting C1 and C2. Presence of the C2 strain at a different prison was determined. ASO-PCR was applied extensively and alerted to the active circulation of one of the strains within and beyond prisons. Our study shows that alternative methodological strategies may provide useful data in settings with lack of resources for performing systematic standard molecular epidemiology programmes and/or with suboptimal material for analysis.

Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail(3-5). Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant's success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes.

We have detected two mutations in the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at amino acid positions 1163 and 1167 that appeared independently in multiple transmission clusters and different genetic backgrounds. Furthermore, both mutations appeared together in a cluster of 1,627 sequences belonging to clade 20E. This cluster is characterized by 12 additional single nucleotide polymorphisms but no deletions. The available structural information on the S protein in the pre- and postfusion conformations predicts that both mutations confer rigidity, which could potentially decrease viral fitness. Accordingly, we observed reduced infectivity of this spike genotype relative to the ancestral 20E sequence in vitro, and the levels of viral RNA in nasopharyngeal swabs were not significantly higher. Furthermore, the mutations did not impact thermal stability or antibody neutralization by sera from vaccinated individuals but moderately reduce neutralization by convalescent-phase sera from the early stages of the pandemic. Despite multiple successful appearances of the two spike mutations during the first year of SARS-CoV- 2 evolution, the genotype with both mutations was displaced upon the expansion of the 20I (Alpha) variant. The midterm fate of the genotype investigated was consistent with the lack of advantage observed in the clinical and experimental data. IMPORTANCE We observed repeated, independent emergence of mutations in the SARS-CoV-2 spike involving amino acids 1163 and 1167, within the HR2 functional motif. Conclusions derived from evolutionary and genomic diversity analysis suggest that the co-occurrence of both mutations might pose an advantage for the virus and therefore a threat to effective control of the epidemic. However, biological characterization, including in vitro experiments and analysis of clinical data, indicated no clear benefit in terms of stability or infectivity. In agreement with this, continuous epidemiological surveillance conducted months after the first observations revealed that both mutations did not successfully outcompete other variants and stopped circulating 9 months after their initial detection. Additionally, we evaluated the potential of both mutations to escape neutralizing antibodies, finding that the presence of these two mutations on their own is not likely to confer antibody escape. Our results provide an example of how newly emerged spike mutations can be assessed to better understand the risk posed by new variants and indicate that some spike mutations confer no clear advantage to the virus despite independently emerging multiple times and are eventually displaced by fitter variants.

Efforts to eradicate tuberculosis are hampered by the rise and spread of antibiotic resistance. Several large-scale projects have aimed to specifically link clinical mutations to resistance phenotypes, but they were limited in both their explanatory and predictive powers. Here, we combine functional genomics and phylogenetic associations using clinical strain genomes to decipher the architecture of isoniazid resistance and search for new resistance determinants. This approach has allowed us to confirm the main target route of the antibiotic, determine the clinical relevance of redox metabolism as an isoniazid resistance mechanism and identify novel candidate genes harboring resistance mutations in strains with previously unexplained isoniazid resistance. This approach can be useful for characterizing how the tuberculosis bacilli acquire resistance to new antibiotics and how to forestall them. Victoria Furio et al. apply functional genomics and evolutionary analyses to the study of antibiotic resistance in tuberculosis. Focusing on isoniazid resistance and using genomic data from clinical strains, they identify novel candidate genes with resistance mutations and further uncover the mechanisms underlying drug resistance.

Recurrent tuberculosis occurs due to exogenous reinfection or reactivation/persistence. We analysed 90 sequential MDR Mtb isolates obtained in Argentina from 27 patients with previously diagnosed MDR-TB that recurred in 2018 (1-10 years, 2-10 isolates per patient). Three long-term predominant strains were responsible for 63% of all MDR-TB recurrences. Most of the remaining patients were infected by strains different from each other. Reactivation/persistence of the same strain caused all but one recurrence, which was due to a reinfection with a predominant strain. One of the prevalent strains showed marked stability in the recurrences, while in another strain higher SNP-based diversity was observed. Comparisons of intra- versus inter-patient SNP distances identified two possible reinfections with closely related variants circulating in the community. Our results show a complex scenario of MDR-TB infections in settings with predominant MDR Mtb strains.

The first descriptions of reinfection by SARS-CoV-2 have been recently reported. However, these studies focus exclusively on the reinfected case, without considering the epidemiological context of the event. Our objectives were to perform a complete analysis of the sequential infections and community transmission events around a SARS-CoV-2 reinfection, including the infection events preceding it, the exposure, and subsequent transmissions. Our analysis was supported by host genetics, viral whole-genome sequencing, phylogenomic viral population analysis, and refined epidemiological data obtained from interviews with the involved subjects. The reinfection involved a 53-year-old woman with asthma (Case A), with a first COVID-19 episode in April 2020 and a much more severe second episode 4-1/2 months later, with SARS-CoV-2 seroconversion in August, that required hospital admission. An extended genomic analysis allowed us to demonstrate that the strain involved in Case A's reinfection was circulating in the epidemiological context of Case A and was also transmitted subsequently from Case A to her family context. The reinfection was also supported by a phylogenetic analysis, including 348 strains from Madrid, which revealed that the strain involved in the reinfection was circulating by the time Case A suffered the second episode, August-September 2020, but absent at the time range corresponding to Case A's first episode. IMPORTANCE We present the first complete analysis of the epidemiological scenario around a reinfection by SARS-CoV-2, more severe than the first episode, including three cases preceding the reinfection, the reinfected case per se, and the subsequent transmission to another seven cases.

Following its emergence in late 2019, the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1,2 has been tracked via phylogenetic analysis of viral genome sequences in unprecedented detail3–5. While the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, within Europe travel resumed in the summer of 2020. Here we report on a novel SARS-CoV-2 variant, 20E (EU1), that emerged in Spain in early summer, and subsequently spread across Europe. We find no evidence of increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant’s success. Despite travel restrictions, we estimate 20E (EU1) was introduced hundreds of times to European countries by summertime travelers, likely undermining local efforts to keep SARS-CoV-2 cases low. Our results demonstrate how a variant can rapidly become dominant even in absence of a substantial transmission advantage in favorable epidemiological settings. Genomic surveillance is critical to understanding how travel can impact SARS-CoV-2 transmission, and thus for informing future containment strategies as travel resumes., This work was supported by the Swiss National Science Foundation (SNSF) through grant numbers 31CA30 196046 (to RAN, EBH, CLA), 31CA30 196267 (to TS), European Union’s Horizon 2020 research and innovation programme - project EpiPose (No 101003688) (MLR, CLA), core funding by the University of Basel and ETH Zürich, the National Institute of General Medical Sciences (R01GM120553 to DV), the National Institute of Allergy and Infectious Diseases (DP1AI158186 and HHSN272201700059C to DV), a Pew Biomedical Scholars Award (DV), an Investigators in the Pathogenesis of Infectious Disease Awards from the Burroughs Wellcome Fund (DV and JDB), a Fast Grants (DV), and NIAID grants R01AI141707 (JDB) and F30AI149928 (KHDC). SeqCOVID-SPAIN is funded by the Instituto de Salud Carlos III project COV20/00140, Spanish National Research Council and ERC StG 638553 to IC and BFU2017-89594R from MICIN to FGC. JDB is an Investigator of the Howard Hughes Medical Institute.

The coronavirus disease 2019 (COVID-19) pandemic has affected the world radically since 2020. Spain was one of the European countries with the highest incidence during the first wave. As a part of a consortium to monitor and study the evolution of the epidemic, we sequenced 2,170 samples, diagnosed mostly before lockdown measures. Here, we identified at least 500 introductions from multiple international sources and documented the early rise of two dominant Spanish epidemic clades (SECs), probably amplified by superspreading events. Both SECs were related closely to the initial Asian variants of SARS-CoV-2 and spread widely across Spain. We inferred a substantial reduction in the effective reproductive number of both SECs due to public-health interventions (R-e < 1), also reflected in the replacement of SECs by a new variant over the summer of 2020. In summary, we reveal a notable difference in the initial genetic makeup of SARS-CoV-2 in Spain compared with other European countries and show evidence to support the effectiveness of lockdown measures in controlling virus spread, even for the most successful genetic variants. Analysis of 2,170 SARS-CoV-2 sequences from the first wave of the COVID-19 epidemic in Spain provides insights into transmission patterns and the effects of lockdown on the emergence of new variants.

Whole genome sequencing (WGS) has been shown to be superior to traditional procedures of genotyping in tuberculosis (TB), nevertheless, reports of its use in drug resistant TB (DR-TB) isolates circulating in Mexico, are practically unknown. Considering the above the main of this work was to identify and characterize the lineages and genomic transmission clusters present in 67 DR-TB isolates circulating in southeastern Mexico. The results show the presence of three major lineages: L1 (3%), L2 (3%) and L4 (94%), the last one included 16 sublineages. Sublineage 4.1.1.3 (X3) was predominant in 18 (27%) of the isolates, including one genomic cluster, formed by eleven multidrug resistant isolates and sharing the SIT 3278, which seems to be restricted to Mexico. By the use of WGS, it was possible to identify the high prevalence of L4 and a high number of sublineages circulating in the region, also was recognized the presence of a novel X3 sublineage, formed exclusively by multidrug resistant isolates and with restrictive circulation in Mexico for at least the past 17 years.

A 77-year-old-male (Case R) who had had a previous diagnosis of mild COVID-19 episode, was hospitalized 35 days later. On Day 23 post-admission, he developed a second COVID-19 episode, now severe, and finally died. Initially, Case R COVID-19 recurrence was interpreted as a reinfection due to the exposure to a SARS-CoV-2 RT-PCR-positive room-mate. However, whole-genome-sequencing indicated that case R recurrence corresponded to a reactivation of the strain involved in his first episode. Case R reactivation had major consequences, leading to a more severe episode, and causing a subsequent transmission to another two hospitalized patients, one of them with fatal outcome.

A 77-year-old-male (Case R) who had had a previous diagnosis of mild COVID-19 episode, was hospitalized 35 days later. On Day 23 post-admission, he developed a second COVID-19 episode, now severe, and finally died. Initially, Case R COVID-19 recurrence was interpreted as a reinfection due to the exposure to a SARS-CoV-2 RT-PCR-positive room-mate. However, whole-genome-sequencing indicated that case R recurrence corresponded to a reactivation of the strain involved in his first episode. Case R reactivation had major consequences, leading to a more severe episode, and causing a subsequent transmission to another two hospitalized patients, one of them with fatal outcome.

Genetic diversity of Mycobacterium tuberculosis affects immune responses and clinical outcomes of tuberculosis (TB). However, how bacterial diversity orchestrates immune responses to direct distinct TB severities is unknown. Here we study 681 patients with pulmonary TB and show that M. tuberculosis isolates from cases with mild disease consistently induce robust cytokine responses in macrophages across multiple donors. By contrast, bacteria from patients with severe TB do not do so. Secretion of IL-1 beta is a good surrogate of the differences observed, and thus to classify strains as probable drivers of different TB severities. Furthermore, we demonstrate that M. tuberculosis isolates that induce low levels of IL-1 beta production can evade macrophage cytosolic surveillance systems, including cGAS and the inflammasome. Isolates exhibiting this evasion strategy carry candidate mutations, generating sigA recognition boxes or affecting components of the ESX-1 secretion system. Therefore, we provide evidence that M. tuberculosis strains manipulate host-pathogen interactions to drive variable TB severities. Some strains of Mycobacterium tuberculosis seem to be able to avoid host defense systems. Here the authors stratify patients by severity of tuberculosis and find correlations with the level of IL-1 beta production by macrophages exposed to these isolates.

Glucocorticoid (GC) actions are mediated through two closely related ligand-dependent transcription factors, the GC receptor (GR) and the mineralocorticoid receptor (MR). Given the wide and effective use of GCs to combat skin inflammatory diseases, it is important to understand the relative contribution of these receptors to the transcriptional response to topical GCs. We evaluated the gene expression profiles in the skin of mice with epidermal-specific loss of GR-(GR(EKO)), MR-(MREKO), or both (double KO; DKO) in response to dexamethasone (Dex). The overall transcriptional response was abolished in GR(EKO) and DKO skin suggesting dependence of the underlying dermis on the presence of epidermal GR. Indeed, the observed dermal GC resistance correlated with a constitutive decrease in GR activity and up-regulation of p38 activity in this skin compartment. Upon Dex treatment, more than 90% of differentially expressed genes (DEGs) in CO overlapped with MREKO. However, the number of DEGs was fourfold increased and the magnitude of response was higher in MREKO vs CO, affecting both gene induction and repression. Taken together our data reveal that, in the cutaneous transcriptional response to GCs mediated through endogenous receptors, epidermal GR is mandatory while epidermal MR acts as a chief modulator of gene expression.

Motivation: Tuberculosis (TB) remains one of the main causes of death worldwide. The long and cumbersome process of culturing Mycobacterium tuberculosis complex (MTBC) bacteria has encouraged the development of specific molecular tools for detecting the pathogen. Most of these tools aim to become novel TB diagnostics, and big efforts and resources are invested in their development, looking for the endorsement of the main public health agencies. Surprisingly, no study has been conducted where the vast amount of genomic data available is used to identify the best MTBC diagnostic markers. Results: In this work, we used large-scale comparative genomics to identify 40 MTBC-specific loci. We assessed their genetic diversity and physiological features to select 30 that are good targets for diagnostic purposes. Some of these markers could be used to assess the physiological status of the bacilli. Remarkably, none of the most used MTBC markers is in our catalog. Illustrating the translational potential of our work, we develop a specific qPCR assay for quantification and identification of MTBC DNA. Our rational design of targeted molecular assays for TB could be used in many other fields of clinical and basic research.

Background Contaminant DNA is a well-known confounding factor in molecular biology and in genomic repositories. Strikingly, analysis workflows for whole-genome sequencing (WGS) data commonly do not account for errors potentially introduced by contamination, which could lead to the wrong assessment of allele frequency both in basic and clinical research. Results We used a taxonomic filter to remove contaminant reads from more than 4000 bacterial samples from 20 different studies and performed a comprehensive evaluation of the extent and impact of contaminant DNA in WGS. We found that contamination is pervasive and can introduce large biases in variant analysis. We showed that these biases can result in hundreds of false positive and negative SNPs, even for samples with slight contamination. Studies investigating complex biological traits from sequencing data can be completely biased if contamination is neglected during the bioinformatic analysis, and we demonstrate that removing contaminant reads with a taxonomic classifier permits more accurate variant calling. We used both real and simulated data to evaluate and implement reliable, contamination-aware analysis pipelines. Conclusion As sequencing technologies consolidate as precision tools that are increasingly adopted in the research and clinical context, our results urge for the implementation of contamination-aware analysis pipelines. Taxonomic classifiers are a powerful tool to implement such pipelines.

Mycobacterium tuberculosis (Mtb) infection results in a spectrum of clinical and histopathologic manifestations. It has been proposed that the environmental and immune pressures associated with different contexts of infection have different consequences for the associated bacterial populations, affecting drug susceptibility and the emergence of resistance. However, there is little concrete evidence for this model. We prospectively collected sputum samples from 18 newly diagnosed and treatment-naive patients with tuberculosis and sequenced 795 colony-derived Mtb isolates. Mutant accumulation rates varied considerably between different bacilli isolated from the same individual, and where high rates of mutation were observed, the mutational spectrum was consistent with reactive oxygen species-induced mutagenesis. Elevated bacterial mutation rates were identified in isolates from HIV-negative but not HIV-positive individuals, suggesting that they were immune-driven. These results support the model that mutagenesis of Mtb in vivo is modulated by the host environment, which could drive the emergence of variants associated with drug resistance in a host-dependent manner.

Tuberculosis (TB) surveillance is scarce in most African countries, even though it is the continent with the greatest disease incidence according to the World Health Organization. Liberia is within the 30 countries with the highest TB burden, probably as a consequence of the long civil war and the recent Ebola outbreak, both crippling the health system and depreciating the TB prevention and control programmes. Due to difficulties working in the country, there is a lack of resistance surveys and bacillus characterization. Here, we use genome sequencing of Mycobacterium tuberculosis clinical isolates to fill this gap. Our results highlight that the bacillus population structure is dominated by lineage 4 strains that harbour an outstanding genetic diversity, higher than in the rest of Africa as a whole. Coalescent analyses demonstrate that strains currently circulating in Liberia were introduced several times beginning in the early year 600 CE until very recently coinciding with migratory movements associated with the civil war and Ebola epidemics. A higher multidrug-resistant (MDR)-TB frequency (23.5 %) than current estimates was obtained together with non-catalogued drug-resistance mutations. Additionally, 39 % of strains were in genomic clusters revealing that ongoing transmission is a major contribution to the TB burden in the country. Our report emphasizes the importance of TB surveillance and control in African countries where bacillus diversity, MDR-TB prevalence and transmission are coalescing to jeopardize TB control programmes.

For the first time, next generation sequencing technologies provide access to genomic information at a price and scale that allow their implementation in routine clinical practice and epidemiology. While there are still many obstacles to their implementation, there are also multiple examples of their major advantages compared with previous methods. Their main advantage is that a single determination allows epidemiological information on the causative microorganism to be obtained simultaneously, as well as its resistance profile, although these advantages vary according to the pathogen under study. This review discusses several examples of the clinical and epidemiological use of next generation sequencing applied to complete genomes and microbiomes and reflects on its future in clinical practice. (C) 2020 Elsevier Espana, S.L.U. and Sociedad Espanola de Enfermedades Infecciosas y Microbiologia Clinica. All rights reserved.

Whole genome sequencing (WGS) has been proposed as a tool for the diagnosis of drug resistance in tuberculosis (TB); however, there have been few studies on its effectiveness in countries with significantly high drug resistance rates. This study therefore aimed to evaluate the effectiveness of WGS to identify mutations related to drug resistance in TB isolates from an endemic region of Mexico. The results showed that, of 35 multidrug-resistant isolates analyzed, the values of congruence found between the phenotypic drug susceptibility testing and polymorphisms were 94% for isoniazid, 97% for rifampicin, 90% for ethambutol, and 82% for pyrazinamide. It was also possible to identify eight isolates as potential pre-extensive drug resistant (XDR) and one as XDR. Twenty nine isolates were classified within L4 and two transmission clusters were identified. The results show the potential utility of WGS for predicting resistance against first- and second-line drugs, as well as providing a phylogenetic characterization of TB drug-resistant isolates circulating in Mexico.

11 págs, 4 figuras y fórmulas matemáticas. Material suplementario en: http://dx.doi.org/10.1093/molbev/msaa069, The dN/dS ratio provides evidence of adaptation or functional constraint in protein-coding genes by quantifying the relative excess or deficit of amino acid-replacing versus silent nucleotide variation. Inexpensive sequencing promises a better understanding of parameters, such as dN/dS, but analyzing very large data sets poses a major statistical challenge. Here, I introduce genomegaMap for estimating within-species genome-wide variation in dN/dS, and I apply it to 3,979 genes across 10,209 tuberculosis genomes to characterize the selection pressures shaping this global pathogen. GenomegaMap is a phylogeny-free method that addresses two major problems with existing approaches: 1) It is fast no matter how large the sample size and 2) it is robust to recombination, which causes phylogenetic methods to report artefactual signals of adaptation. GenomegaMap uses population genetics theory to approximate the distribution of allele frequencies under general, parent-dependent mutation models. Coalescent simulations show that substitution parameters are well estimated even when genomegaMap's simplifying assumption of independence among sites is violated. I demonstrate the ability of genomegaMap to detect genuine signatures of selection at antimicrobial resistance-conferring substitutions in Mycobacterium tuberculosis and describe a novel signature of selection in the cold-shock DEAD-box protein A gene deaD/csdA. The genomegaMap approach helps accelerate the exploitation of big data for gaining new insights into evolution within species., D.J.W. is a Sir Henry Dale Fellow, jointly funded by the Wellcome Trust and the Royal Society (grant no. 101237/Z/13/B) and is a Big Data Institute Robertson Fellow. The CRyPTIC Consortium was supported by grants from the Bill and Melinda Gates Foundation (OPP1133541) and a Wellcome Trust/Newton Fund-MRC Collaborative Award (200205/Z/15/Z). F.A.D. was supported by the Imperial Biomedical Research Centre

Background: The analysis of transmission of tuberculosis (TB) is challenging in areas with a large migrant population. Standard genotyping may fail to differentiate transmission within the host country from new importations, which is key from an epidemiological perspective. Aim: To propose a new strategy to simplify and optimise cross-border surveillance of tuberculosis and to distinguish between recent transmission in the host country and new importations. Methods: We selected 10 clusters, defined by 24-locus mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR), from a population in Spain rich in migrants from eastern Europe, north Africa and west Africa and reanalysed 66 isolates by whole-genome sequencing (WGS). A multiplex-allele-specific PCR was designed to target strain-specific marker single nucleotide polymorphisms (SNPs), identified from WGS data, to optimise the surveillance of the most complex cluster. Results: In five of 10 clusters not all isolates showed the short genetic distances expected for recent transmission and revealed a higher number of SNPs, thus suggesting independent importations of prevalent strains in the country of origin. In the most complex cluster, rich in Moroccan cases, a multiplex allele-specific oligonucleotide-PCR (ASO-PCR) targeting the marker SNPs for the transmission subcluster enabled us to prospectively identify new secondary cases. The ASO-PCR-based strategy was transferred and applied in Morocco, demonstrating that the strain was prevalent in the country. Conclusion: We provide a new model for optimising the analysis of cross-border surveillance of TB transmission in the scenario of global migration.

The Mycobacterium tuberculosis complex (MTBC) members display different host-specificities and virulence phenotypes. Here, we have performed a comprehensive RNAseq and methylome analysis of the main clades of the MTBC and discovered unique transcriptional profiles. The majority of genes differentially expressed between the clades encode proteins involved in host interaction and metabolic functions. A significant fraction of changes in gene expression can be explained by positive selection on single mutations that either create or disrupt transcriptional start sites (TSS). Furthermore, we show that clinical strains have different methyltransferases inactivated and thus different methylation patterns. Under the tested conditions, differential methylation has a minor direct role on transcriptomic differences between strains. However, disruption of a methyltransferase in one clinical strain revealed important expression differences suggesting indirect mechanisms of expression regulation. Our study demonstrates that variation in transcriptional profiles are mainly due to TSS mutations and have likely evolved due to differences in host characteristics.

Background Whole genome sequencing (WGS) has been proposed as a tool for diagnosing drug resistance in tuberculosis. However, reports of its effectiveness in endemic countries with important numbers of drug resistance are scarce. The goal of this study was to evaluate the effectiveness of this procedure in isolates from a tuberculosis endemic region in Mexico. Methods WGS analysis was performed in 81 tuberculosis positive clinical isolates with a known phenotypic profile of resistance against first-line drugs (isoniazid, rifampin, ethambutol, pyrazinamide and streptomycin). Mutations related to drug resistance were identified for each isolate; drug resistant genotypes were predicted and compared with the phenotypic profile. Genotypes and transmission clusters based on genetic distances were also characterized. Findings Prediction by WGS analysis of resistance against isoniazid, rifampicin, ethambutol, pyrazinamide and streptomycin showed sensitivity values of 84%, 96%, 71%, 75% and 29%, while specificity values were 100%, 94%, 90%, 90% and 98%, respectively. Prediction of multidrug resistance showed a sensitivity of 89% and specificity of 97%. Moreover, WGS analysis revealed polymorphisms related to second-line drug resistance, enabling classification of eight and two clinical isolates as pre- and extreme drug-resistant cases, respectively. Lastly, four lineages were identified in the population (L1, L2, L3 and L4). The most frequent of these was L4, which included 90% (77) of the isolates. Six transmission clusters were identified; the most frequent was TC6, which included 13 isolates with a L4.1.1 and a predominantly multidrug-resistant condition. Conclusions The results illustrate the utility of WGS for establishing the potential for prediction of resistance against first and second line drugs in isolates of tuberculosis from the region. They also demonstrate the feasibility of this procedure for use as a tool to support the epidemiological surveillance of drug-and multidrug-resistant tuberculosis.

Al llarg de la seva vida, Pompeu Fabra va mantenir relacions amb diversos personatges de Mataró, com ara Jaume Baladia i Soler, Josep Puig i Cadafalch i Julià Gual i Masoller, o amb altres que tenien vincles maratonins, com Emili Guanyavents i Jané i Francesc Matheu i Fornells. En aquest article, Anna Comas i Valls ressegueix aquestes relacions i els vincles del Mestre amb la nostra ciutat, alhora que fa un recorregut per la seva bibliografia i per la dels personatges mataroninsamb qui es relacionà, tot contextualitzant-les en els diversos períodes històrics que travessen, des dels finals del segle XIX fins a mitjan segle XX.

Understanding why some multidrug-resistant tuberculosis cases are not detected by rapid phenotypic and genotypic routine clinical tests is essential to improve diagnostic assays and advance toward personalized tuberculosis treatment. Here, we combine whole-genome sequencing with single-colony phenotyping to identify a multidrug-resistant strain that had infected a patient for 9 years. Our investigation revealed the failure of rapid testing and genome-based prediction tools to identify the multidrug-resistant strain. The false-negative findings were caused by uncommon rifampicin and isoniazid resistance mutations. Although whole-genome sequencing data helped to personalize treatment, the patient developed extensively drug-resistant tuberculosis, highlighting the importance of coupling new diagnostic methods with appropriate treatment regimens.

13 páginas, 4 figuras. Contiene material suplementario., Whole genome sequencing (WGS) of Mycobacterium tuberculosis has rapidly progressed from a research tool to a clinical application for the diagnosis and management of tuberculosis and in public health surveillance. This development has been facilitated by drastic drops in cost, advances in technology and concerted efforts to translate sequencing data into actionable information. There is, however, a risk that, in the absence of a consensus and international standards, the widespread use of WGS technology may result in data and processes that lack harmonization, comparability and validation. In this Review, we outline the current landscape of WGS pipelines and applications, and set out best practices for M. tuberculosis WGS, including standards for bioinformatics pipelines, curated repositories of resistance-causing variants, phylogenetic analyses, quality control and standardized reporting., C.J.M., B.O.-A., L.R. and B.C.d.J. are supported by a European Research Council grant (INTERRUPTB; no. 311725). I.C. and G.A.G. are supported by a European Research Council grant (TB-ACCELERATE; no. 638553). T.C.R. receives salary support from the not-for-profit organization Foundation for Innovative New Diagnostics (the terms of this arrangement have been reviewed and approved by the University of California, San Diego). T.M.W. is an NIHR Academic Clinical Lecturer. J.L.G. and J.G. receive funding from the University of British Columbia, Vancouver, Canada. T.A.K., C.U., V.D. and S.N. receive funding from the German Center for Infection Research (DZIF) and are funded by the Deutsche Forschungsgemeinschaft (German Research Foundation) under Germany’s Excellence Strategy (EXC 22167–390884018). L.V., T.H.H. and A.V.R. are funded by FWO Odysseus G0F8316N. M.R.F. is supported by the US National Institutes of Health BD2K K01 (MRF ES026835). P.S. is supported by the Agence Nationale de la Recherche (ANR-16-CE35-0009).

Background: Mycobacterium tuberculosis (MTB) has limited ability to acquire variability. Analysis of its microevolution might help us to evaluate the pathways followed to acquire greater infective success. Whole-genome sequencing (WGS) in the analysis of the transmission of MTB has elucidated the magnitude of variability in MTB. Analysis of transmission currently depends on the identification of clusters, according to the threshold of variability (

In this work, 12 spin-spin coupling constants (J) obtained experimentally for the Ala3 peptide are used to determine the secondary structure of its central amino acid. For this purpose, a procedure is used that does not assume any main conformation, but considers the entire Ramachandran diagram without limiting it to specific areas. In addition, the algorithm considers the possibility that the value of each observed J is the result of the contribution of different structures/conformations, with the corresponding weights. In order to apply this procedure, it is necessary to know the value of each J for any combination of the dihedral angles ɸ and Ψ of the central amino acid. This is achieved through the Density Functional Theory. Firstly, the 625 structures generated by fixing the dihedral angles ɸ and Ψ are optimized at intervals of 15o at the B3LYP/D95(d,p) level of theory. The values of the 12 J are calculated for each structure with different functionals and basis sets in order to determine their possible effects, and the results are represented as a function of ɸ and Ψ, thus obtaining two-dimensional plots for each J. With these grids it can be observed that one-dimensional Karplus equations are not applicable in general, since with the exception of the constants 3J(C6-H14), 3J(C6-C15) and 3J(C6-C16), the values of J show dependence with the two dihedral angles. The effect of the solvent in the J calculations is also introduced, although it is quickly discarded due to the large deviations obtained with respect to the experimental data. The combination of the functional MPW1WK and the basis set 6-31G-J gives the best results according to the mean deviation (RMSD) with respect to the experimental J values, but the structures that are obtained do not correspond to expected conformations. On the other hand, by calculating the J with the functional MPW1WK and the uncontracted basis set D95 (d,p), the error is slightly higher but the structures obtained fully correspond with alpha helix, beta sheet and polyproline II helix conformations. In this way the functional MPW1WK significantly improves the results obtained with respect to previous reference calculations, where the functional B3LYP with the base D95 (d, p) had been used

Background: The World Health Organization recommends drug-susceptibility testing of Mycobacterium tuberculosis complex for all patients with tuberculosis to guide treatment decisions and improve outcomes. Whether DNA sequencing can be used to accurately predict profiles of susceptibility to first-line antituberculosis drugs has not been clear.\ud \ud \ud \ud Methods: We obtained whole-genome sequences and associated phenotypes of resistance or susceptibility to the first-line antituberculosis drugs isoniazid, rifampin, ethambutol, and pyrazinamide for isolates from 16 countries across six continents. For each isolate, mutations associated with drug resistance and drug susceptibility were identified across nine genes, and individual phenotypes were predicted unless mutations of unknown association were also present. To identify how whole-genome sequencing might direct first-line drug therapy, complete susceptibility profiles were predicted. These profiles were predicted to be susceptible to all four drugs (i.e., pansusceptible) if they were predicted to be susceptible to isoniazid and to the other drugs or if they contained mutations of unknown association in genes that affect susceptibility to the other drugs. We simulated the way in which the negative predictive value changed with the prevalence of drug resistance.\ud \ud \ud \ud Results: A total of 10,209 isolates were analyzed. The largest proportion of phenotypes was predicted for rifampin (9660 [95.4%] of 10,130) and the smallest was predicted for ethambutol (8794 [89.8%] of 9794). Resistance to isoniazid, rifampin, ethambutol, and pyrazinamide was correctly predicted with 97.1%, 97.5%, 94.6%, and 91.3% sensitivity, respectively, and susceptibility to these drugs was correctly predicted with 99.0%, 98.8%, 93.6%, and 96.8% specificity. Of the 7516 isolates with complete phenotypic drug-susceptibility profiles, 5865 (78.0%) had complete genotypic predictions, among which 5250 profiles (89.5%) were correctly predicted. Among the 4037 phenotypic profiles that were predicted to be pansusceptible, 3952 (97.9%) were correctly predicted.\ud \ud \ud \ud Conclusions: Genotypic predictions of the susceptibility of M. tuberculosis to first-line drugs were found to be correlated with phenotypic susceptibility to these drugs. (Funded by the Bill and Melinda Gates Foundation and others.)

Every year, species of the Mycobacterium tuberculosis complex (MTBC) kill more people than any other infectious disease caused by a single agent. As a consequence of its global distribution and parallel evolution with the human host the bacteria is not genetically homogeneous. The observed genetic heterogeneity has relevance at different phenotypic levels, from gene expression to epidemiological dynamics. However, current systems biology datasets have focused on the laboratory reference strain H37Rv. By using large expression datasets testing the role of almost two hundred transcription factors, we have constructed computational models to grab the expression dynamics of Mycobacterium tuberculosis H37Rv genes. However, we have found that many of those transcription factors are deleted or likely dysfunctional across strains of the MTBC. As a result, we failed to predict expression changes in strains with a different genetic background when compared with experimental data. These results highlight the importance of designing systems biology approaches that take into account the genetic diversity of tubercle bacilli, or any other pathogen, if we want to identify universal targets for vaccines, diagnostics and treatments.

The role of clonal complexity has gradually been accepted in infection by Mycobacterium tuberculosis (MTB), although analyses of this issue are limited. We performed an in-depth study of a case of recurrent MTB infection by integrating genotyping, whole genome sequencing, analysis of gene expression and infectivity in in vitro and in vivo models. Four different clonal variants were identified from independent intrapatient evolutionary branches. One of the single-nucleotide polymorphisms in the variants mapped in mce3R, which encodes a repressor of an operon involved in virulence, and affected expression of the operon. Competitive in vivo and in vitro co-infection assays revealed higher infective efficiency for one of the clonal variants. A new clonal variant, which had not been observed in the clinical isolates, emerged in the infection assays and showed higher fitness than its parental strain. The analysis of other patients involved in the same transmission cluster revealed new clonal variants acquired through novel evolutionary routes, indicating a high tendency toward microevolution in some strains that is not host-dependent. Our study highlights the need for integration of various approaches to advance our knowledge of the role and significance of microevolution in tuberculosis.