Search

15 páginas, 5 figuras, 1 tabla, Outbreak strains of Mycobacterium tuberculosis are promising candidates as targets in the search for intrinsic determinants of transmissibility, as they are responsible for many cases with sustained transmission; however, the use of low-resolution typing methods and restricted geographical investigations represent flaws in assessing the success of long-lived outbreak strains. We can now address the nature of outbreak strains by combining large genomic data sets and phylodynamic approaches. We retrospectively sequenced the whole genome of representative samples assigned to an outbreak circulating in the Canary Islands (the GC strain) since 1993, which accounts for ~20% of local tuberculosis cases. We selected a panel of specific single nucleotide polymorphism (SNP) markers for an in-silico search for additional outbreak-related sequences within publicly available tuberculosis genomic data. Using this information, we inferred the origin, spread, and epidemiological parameters of the GC strain. Our approach allowed us to accurately trace the historical and more recent dispersion of the GC strain. We provide evidence of a highly successful nature within the Canarian archipelago but limited expansion abroad. Estimation of epidemiological parameters from genomic data disagree with a distinctive biology of the GC strain. With the increasing availability of genomic data allowing for the accurate inference of strain spread and critical epidemiological parameters, we can now revisit the link between Mycobacterium tuberculosis genotypes and transmission, as is routinely carried out for SARS-CoV-2 variants of concern. We demonstrate that social determinants rather than intrinsically higher bacterial transmissibility better explain the success of the GC strain. Importantly, our approach can be used to trace and characterize strains of interest worldwide. IMPORTANCE Infectious disease outbreaks represent a significant problem for public health. Tracing outbreak expansion and understanding the main factors behind emergence and persistence remain critical to effective disease control. Our study allows researchers and public health authorities to use Whole-Genome Sequencing-based methods to trace outbreaks, and shows how available epidemiological information helps to evaluate the factors underpinning outbreak persistence. Taking advantage of all the freely available information placed in public repositories, researchers can accurately establish the expansion of an outbreak beyond original boundaries, and determine the potential risk of a strain to inform health authorities which, in turn, can define target strategies to mitigate expansion and persistence. Finally, we show the need to evaluate strain transmissibility in different geographic contexts to unequivocally associate spread to local or pathogenic factors, an important lesson taken from genomic surveillance of SARS-CoV-2., This project has been funded by the European Research Council (101001038-TBRECONNECT), the Ministerio de Economía, Industria y Competitividad (PID2019-104477RB-I00), and the European Commission–NextGenerationEU (Regulation EU 2020/2094), through CSIC's Global Health Platform (PTI Salud Global) to I.C. This project has been funded by the Instituto de Salud Carlos III (FIS18/0336) and the Gobierno de Aragón/Fondo Social Europeo “Construyendo Europa desde Aragón” to SS

14 paginas, 5 figuras, 2 tablas., 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., This project received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programmes 101001038 (TB-RECONNECT), PID2019-104477RB-I00 from Ministerio de Economía y Competitividad (Spanish Government) (to I.C.). We acknowledge support from the Spanish Ministry of Science, Innovation and Universities through the ‘Centro de Excelencia Severo Ochoa 2019–2023’.Programme (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Programme. B.S receives a pre-doctoral fellowship from the Secretariat of Universities and Research, Ministry of Enterprise and Knowledge of the Government of Catalonia and co-funded by European Social Fund (AGAUR).

Genomic studies of 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. We applied Whole-genome sequencing (WGS) to characterize the local population of MTBC, unravel potential transmission links and evaluate associations with host and pathogen factors. Methods A one-year prospective study was conducted in Mozambique, a high HIV/TB burden country. WGS was applied to 295 positive cultures. We combined phylogenetic, geographical and clustering analysis, and investigated associations between risk factors of transmission. Findings A significant high proportion of strains were in recent transmission (45.5%). We fully characterized MTBC isolates by using phylogenetic approaches and dating evaluation. We found two likely endemic clades, comprised of 67 strains, belonging to L1.2, dating from the late XIX century and associated with recent spread among PLHIV. Interpretation Our results unveil the population structure of MTBC in our setting. The clustering analysis revealed an unexpected pattern of spread and high rates of progression, suggesting the failure of control measures. The long-term presence of local strains in Mozambique, which were responsible for large transmission among HIV/TB coinfected patients, hint at possible coevolution with sympatric host populations and challenge the role of HIV in TB transmission., Ministry of Enterprise and Knowledge (Government of Catalonia & European Social Fund, AGAUR fellowship); European Research Council (ERC) European Union’s Horizon 2020.

23 páginas, 4 figuras, 1 tabla., Transmission is a driver of tuberculosis (TB) epidemics in high-burden regions, with assumed negligible impact in low-burden areas. However, we still lack a full characterization of transmission dynamics in settings with similar and different burdens. Genomic epidemiology can greatly help to quantify transmission, but the lack of whole genome sequencing population-based studies has hampered its application. Here, we generate a population-based dataset from Valencia region and compare it with available datasets from different TB-burden settings to reveal transmission dynamics heterogeneity and its public health implications. We sequenced the whole genome of 785 Mycobacterium tuberculosis strains and linked genomes to patient epidemiological data. We use a pairwise distance clustering approach and phylodynamic methods to characterize transmission events over the last 150 years, in different TB-burden regions. Our results underscore significant differences in transmission between low-burden TB settings, i.e., clustering in Valencia region is higher (47.4%) than in Oxfordshire (27%), and similar to a high-burden area as Malawi (49.8%). By modeling times of the transmission links, we observed that settings with high transmission rate are associated with decades of uninterrupted transmission, irrespective of burden. Together, our results reveal that burden and transmission are not necessarily linked due to the role of past epidemics in the ongoing TB incidence, and highlight the need for in-depth characterization of transmission dynamics and specifically tailored TB control strategies., European Research Council 638553-TB-ACCELERATE; European Research Council 101001038-TBRECONNECT; Ministerio de Ciencia e Innovación SAF2016-77346-R

Molecular epidemiology of SARS-CoV-2 aims to monitor the appearance of new variants with the potential to change the virulence or transmissibility of the virus. During the first year of SARS-CoV-2 evolution, numerous variants with possible public health impact have emerged. We have detected two mutations in the Spike protein at amino acid positions 1163 and 1167 that have appeared independently multiple times in different genetic backgrounds, indicating they may increase viral fitness. Interestingly, the majority of these sequences appear in transmission clusters, with the genotype encoding mutations at both positions increasing in frequency more than single-site mutants. This genetic outcome that we denote as Lineage B.1.177.637, belongs to clade 20E and includes 12 additional single nucleotide polymorphisms but no deletions with respect to the reference genome (first sequence in Wuhan). B.1.177.637 appeared after the first wave of the epidemic in Spain, and subsequently spread to eight additional countries, increasing in frequency among sequences in public databases. Positions 1163 and 1167 of the Spike protein are situated in the HR2 domain, which is implicated in the fusion of the host and viral membranes. To better understand the effect of these mutations on the virus, we examined whether B.1.177.637 altered infectivity, thermal stability, or antibody sensitivity. Unexpectedly, we observed reduced infectivity of this variant relative to the ancestral 20E variant in vitro while the levels of viral RNA in nasopharyngeal swabs did not vary significantly. In addition, we found the mutations do not impact thermal stability or antibody susceptibility in vaccinated individuals but display a moderate reduction in sensitivity to neutralization by convalescent sera from early stages of the pandemic. Altogether, this lineage could be considered a Variant of Interest (VOI), we denote VOI1163.7. Finally, we detected a sub-cluster of sequences within VOI1163.7 that have acquired two additional changes previously associated with antibody escape and it could be identified as VOI1163.7.V2. Overall, we have detected the spread of a new Spike variant that may be advantageous to the virus and whose continuous transmission poses risks by the acquisition of additional mutations that could affect pre-existing immunity., This work was funded by the Instituto de Salud Carlos III project COV20/00140 and COV20/00437, Spanish National Research Council project CSIC-COV19-021 and CSIC-COVID19-082, and the Generalitat Valenciana (SEJI/2019/011 and Covid_19-SCI). Action co-financed by the European Union through the Operational Program of the European Regional Development Fund (ERDF) of the Valencian Community 2014-2020. M.C. and R.G. are supported by Ramon y Cajal program from Ministerio de Ciencia.

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., This work was funded by the Instituto de Salud Carlos III project COV20/00140 and COV20/00437, Spanish National Research Council project CSIC-COV19-021 and CSIC-COVID19-082, and the Generalitat Valenciana (SEJI/2019/011 and Covid_19-SCI). Action co-financed by the European Union through the Operational Program of the European Regional Development Fund (ERDF) of the Valencian Community 2014-2020. M.C. and R.G. are supported by Ramon y Cajal program from Ministerio de Ciencia.

Trabajo presentado al 31st European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), celebrado online del 9 al 12 de julio de 2021., This work was funded by the Instituto de Salud Carlos III project COV2o/oo140 and COV2o/ o0437,Spanish National Research Council project CSIC­ COV19·0l1 and CSIC-COVID19-082,and the Generalitat Valenciana (SEJI/2019/011 and Covid_19-SCI).Action co-financed by the European Union through the Operatianal Program of the European Regional Development Fund (ERDF) of the Valencian Community 2014-2020.MC is supported by Ramón y Cajal program from Ministerio de Ciencia,grant RTI2018-094399-A-I00.

The COVID-19 pandemic has shaken the world since the beginning of 2020. Spain is among the European countries with the highest incidence of the disease during the first pandemic wave. We established a multidisciplinar consortium to monitor and study the evolution of the epidemic, with the aim of contributing to decision making and stopping rapid spreading across the country. We present the results for 2170 sequences from the first wave of the SARS-Cov-2 epidemic in Spain and representing 12% of diagnosed cases until 14th March. This effort allows us to document at least 500 initial introductions, between early February-March from multiple international sources. Importantly, we document the early raise of two dominant genetic variants in Spain (Spanish Epidemic Clades), named SEC7 and SEC8, likely amplified by superspreading events. In sharp contrast to other non-Asian countries those two variants were closely related to the initial variants of SARS-CoV-2 described in Asia and represented 40% of the genome sequences analyzed. The two dominant SECs were widely spread across the country compared to other genetic variants with SEC8 reaching a 60% prevalence just before the lockdown. Employing Bayesian phylodynamic analysis, we inferred a reduction in the effective reproductive number of these two SECs from around 2.5 to below 0.5 after the implementation of strict public-health interventions in mid March. The effects of lockdown on the genetic variants of the virus are reflected in the general replacement of preexisting SECs by a new variant at the beginning of the summer season. Our results reveal a significant difference in the genetic makeup of the epidemic in Spain and support the effectiveness of lockdown measures in controlling virus spread even for the most successful genetic variants. Finally, earlier control of SEC7 and particularly SEC8 might have reduced the incidence and impact of COVID-19 in our country., This work was funded by the Instituto de Salud Carlos III project COV20/00140, Spanish 593 National Research Council project CSIC-COV19-021 and ERC StG 638553 to IC, and BFU2017- 594 89594R to FGC. MC is supported by Ramón y Cajal program from Ministerio de Ciencia and 595 grants RTI2018-094399-A-I00 and SEJI/2019/011. 596 We gratefully acknowledge Hospital Universitari Vall d'Hebron, Instituto de Salud Carlos 597 III, IrsiCaixa AIDS Research Lab and all the international researchers and institutions that 598 submitted sequenced SARS-CoV-2 genomes to the GISAID’s EpiCov™ Database, as an 599 important part of our analyses have been made possible by the share of their work.

Informe Científico, 34 páginas, En nombre de SeqCOVID - consorcio para la epidemiología genómica de SARS-CoV-2 en España (lista de autores: http://seqcovid.csic.es/collaborating-institutions/), El consorcio de secuenciación SeqCOVID ha permitido, unido a secuencias depositadas por otras instituciones, colocar a España como el segundo país europeo y cuarto del mundo en número de secuencias generadas del virus. La primera ola en España ha sido analizada a la luz de la información genómica de 2170 pacientes de todo el país. Los análisis identifican más de 500 introducciones en el país dentro del total de 2170 muestras analizadas. Por tanto, no existe un paciente 0. La mayor parte a partir de mediados de Febrero. La primera ola estuvo dominada por hasta nueve genotipos exitosos. En concreto, identificamos un genotipo que representa como media el 30% de nuestras secuencias y llega representar el 60% las primeras semanas de Marzo. Se caracteriza por una serie de eventos consecutivos que hemos podido reconstruir relativamente bien: Segunda quincena Febrero. Entradas múltiples por Valencia (partido de fútbol Atalanta-Valencia) y Madrid (ferias de arte y visita de casos valencianos). Probablemente por más sitios, pero no tenemos acceso a la información epidemiológica detallada. Finales de Febrero. Eventos de superdispersión como el de Vitoria. El de Vitoria se corresponde con el brote por un funeral. Llega a población general en País Vasco y La Rioja incluyendo residencia de ancianos. Esto aumenta la frecuencia del genotipo y evita su extinción. Principios de Marzo. Movilidad a toda España incluyendo las islas en menos de diez días desde las entradas conocidas. (Figura 1). En la primera semana de Marzo el genotipo representa el 60% de casos de todos los secuenciados. El confinamiento es altamente efectivo con la desaparición de muchos de estos genotipos exitosos., Este proyecto está financiado por el Instituto de Salud Carlos III con código COV20/00140 financiado por el Gobierno de España así como por la PTI Salud Global del Consejo Superior de Investigaciones Científicas financiada a través de donaciones de diferentes empresas que se pueden consultar (https://pti-saludglobal-covid19.corp.csic.es/). Para la Comunidad Valenciana hemos contado con financiación y apoyo de la Conselleria de Sanitat Universal i Salut Pública de la Generalitat Valenciana (a Fernando González Candelas). Queremos reconocer la labor de los miembros del consorcio y sus instituciones que han apoyado logísticamente y con recursos humanos el proyecto. Queremos reconocer a los pacientes participantes. Una gran parte de los análisis presentados han sido gracias a las instalaciones de computación asociadas a la Unidad de análisis computacional y bioestadística del Centro de Investigación Príncipe Felipe. Gran parte de la secuenciación se ha llevado a cabo en el Servicio de Secuenciación y de Bioinformática de FISABIO. Determinadas muestras requirieron el uso del laboratorio de bioseguridad P2+ y P3 de FISABIO. Todas estas instalaciones han sido financiadas en gran medida por el Fondo Europeo de Desarrollo Regional “Una manera de hacer Europa”.

11 páginas, 4 figuras, 1 tabla y fórmulas. Plots of all trajectories calculated (Dataset S7) have been deposited in Figshare (https://dx.doi.org/10.6084/m9.figshare.19335854). Previously published data were also used for this work [data from Brites et al. (4), Coll et al. (29), Stucki et al. (30), Guerra-Assunc¸~ao et al. (31), Zignol et al. (32), Bos et al. (33), Ates et al. (34), Comas et al. (10, 35), Borrell et al. (36), and Cancino-Mu~noz et al. (37)]., SignificancePrevious attempts to identify the action of natural selection in the Mycobacterium tuberculosis complex (MTBC) were limited by sample size and averaging across time and lineages. We investigate changes in selective pressures across time for every single gene of the MTBC. We developed a methodology to analyze temporal signals of selection in a large dataset (∼5,000 complete genomes) and showed that 1) almost half of the genes seem to have been under positive selection at some point in time; 2) experimentally confirmed epitopes tend to accumulate more mutations in deeper branches than in external branches; and 3) temporal signals identify genes that were conserved in the past but under positive selection in the present, suggesting ongoing adaptation to the host., This project received funding from the European Research Council under the European Union’s Horizon 2020 Research and Innovation Program Grant 101001038 (TB-RECONNECT). In addition, this work was funded by Ministerio de Ciencia (Spanish Government) Project PID2019- 104477RB-I00 and Generalitat Valenciana Project AICO/2018/113. This research work was also funded by the European Commission – NextGenerationEU (Regulation EU 2020/2094), through CSIC's Global Health Platform (PTI Salud Global)

12 páginas, 5 figuras, 2 tablas. DNA sequences generated as part of this study have been deposited at the European Nucleotide Archive under study accession number PRJEB32589 (Table S1) (2019), 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., This work was supported by the European Research Council (638553-TB-ACCELERATE) and the Ministerio de Economía y Competitividad (SAF2013-43521-R and SAF2016-77346-R to I.C.). Funding support from the John D. and Catherine T. MacArthur Foundation, USA, under the Higher Education Initiative in Africa (grant no. 97944-0-800/406/99) for the establishment of the Center for Control and Prevention of Zoonoses, University of Ibadan, Nigeria, is appreciated.