Effect of oligonucleotide primers in determining viral variability within hosts

BACKGROUND: Genetic variability in viral populations is usually estimated by means of polymerase chain reaction (PCR) based methods in which the relative abundance of each amplicon is assumed to be proportional to the frequency of the corresponding template in the initial sample. Although bias in template-to-product ratios has been described before, its relevance in describing viral genetic variability at the intrapatient level has not been fully assessed yet. RESULTS: To investigate the role of oligonucleotide design in estimating viral variability within hosts, genetic diversity in hepatitis C virus (HCV) populations from eight infected patients was characterised by two parallel PCR amplifications performed with two slightly different sets of primers, followed by cloning and sequencing (mean = 89 cloned sequences per patient). Population genetics analyses of viral populations recovered by pairs of amplifications revealed that in seven patients statistically significant differences were detected between populations sampled with different set of primers. CONCLUSIONS: Genetic variability analyses demonstrates that PCR selection due to the choice of primers, differing in their degeneracy degree at some nucleotide positions, can eclipse totally or partially viral variants, hence yielding significant different estimates of viral variability within a single patient and therefore eventually producing quite different qualitative and quantitative descriptions of viral populations within each host

Evidence of Recombination in Intrapatient Populations of Hepatitis C Virus

Hepatitis C virus (HCV) is a major cause of liver disease worldwide and a potential cause of substantial morbidity and mortality in the future. HCV is characterized by a high level of genetic heterogeneity. Although homologous recombination has been demonstrated in many members of the family Flaviviridae, to which HCV belongs, there are only a few studies reporting recombination on natural populations of HCV, suggesting that these events are rare in vivo. Furthermore, these few studies have focused on recombination between different HCV genotypes/subtypes but there are no reports on the extent of intra-genotype or intra-subtype recombination between viral strains infecting the same patient. Given the important implications of recombination for RNA virus evolution, our aim in this study has been to assess the existence and eventually the frequency of intragenic recombination on HCV. For this, we retrospectively have analyzed two regions of the HCV genome (NS5A and E1-E2) in samples from two different groups: (i) patients infected only with HCV (either treated with interferon plus ribavirin or treatment naïve), and (ii) HCV-HIV co-infected patients (with and without treatment against HIV). The complete data set comprised 17712 sequences from 136 serum samples derived from 111 patients. Recombination analyses were performed using 6 different methods implemented in the program RDP3. Recombination events were considered when detected by at least 3 of the 6 methods used and were identified in 10.7% of the amplified samples, distributed throughout all the groups described and the two genomic regions studied. The resulting recombination events were further verified by detailed phylogenetic analyses. The complete experimental procedure was applied to an artificial mixture of relatively closely viral populations and the ensuing analyses failed to reveal artifactual recombination. From these results we conclude that recombination should be considered as a potentially relevant mechanism generating genetic variation in HCV and with important implications for the treatment of this infection

Genomic analysis of Mycobacterium brumae sustains its nonpathogenic and immunogenic phenotype

Mycobacterium brumae is a rapid-growing, non-pathogenic Mycobacterium species, originally isolated from environmental and human samples in Barcelona, Spain. Mycobacterium brumae is not pathogenic and it's in vitro phenotype and immunogenic properties have been well characterized. However, the knowledge of its underlying genetic composition is still incomplete. In this study, we first describe the 4 Mb genome of the M. brumae type strain ATCC 51384T assembling PacBio reads, and second, we assess the low intraspecies variability by comparing the type strain with Illumina reads from three additional strains. Mycobacterium brumae genome is composed of a circular chromosome with a high GC content of 69.2% and containing 3,791 CDSs, 97 pseudogenes, one prophage and no CRISPR loci. Mycobacterium brumae has shown no pathogenic potential in in vivo experiments, and our genomic analysis confirms its phylogenetic position with other non-pathogenic and rapid growing mycobacteria. Accordingly, we determined the absence of virulence-related genes, such as ESX-1 locus and most PE/PPE genes, among others. Although the immunogenic potential of M. brumae was proved to be as high as Mycobacterium bovis BCG, the only mycobacteria licensed to treat cancer, the genomic content of M. tuberculosis T cell and B cell antigens in M. brumae genome is considerably lower than those antigens present in M. bovis BCG genome. Overall, this work provides relevant genomic data on one of the species of the mycobacterial genus with high therapeutic potential

Epstein-Barr virus in oral proliferative verrucous leukoplakia and squamous cell carcinoma : a preliminary study

The aim of this study was to analyze proliferative verrucous leukoplakia (PVL) and oral squamous cell carcinoma (OSCC) for the possible presence of Epstein-Barr virus (EBV). We studied three groups: Sub-Group 1 was composed of 10 patients with PVL, (6 of whom had developed OSCC); Sub-Group 2 comprised 5 patients with OSCC but no preceding PVL; and Sub-Group 3 were 5 controls with clinically normal oral mucosa. Oral biopsies from all cases were examined for Epstein-Barr virus (EBV) by nested PCR. EBV was detected in 60% of Sub-Group 1 patients (PVL ) and in 40% of Sub-Group 2 (OSCC), but in 0% of SubGroup 3 (controls)

Prevalence of SARS-CoV-2 and co-occurrence/co-infection with malaria during the first wave of the pandemic (the Burkina Faso case)

Africa accounts for 1.5% of the global coronavirus disease 2019 (COVID-19) cases and 2.7% of deaths, but this low incidence has been partly attributed to the limited testing capacity in most countries. In addition, the population in many African countries is at high risk of infection with endemic infectious diseases such as malaria. Our aim is to determine the prevalence and circulation of SARS-CoV-2 variants, and the frequency of co-infection with the malaria parasite. We conducted serological tests and microscopy examinations on 998 volunteers of different ages and sexes in a random and stratified population sample in Burkina-Faso. In addition, nasopharyngeal samples were taken for RT-qPCR of SARS-COV-2 and for whole viral genome sequencing. Our results show a 3.2% and a 2.5% of SARS-CoV-2 seroprevalence and PCR positivity; and 22% of malaria incidence, over the sampling period, with marked differences linked to age. Importantly, we found 2 cases of confirmed co-infection and 8 cases of suspected co-infection mostly in children and teenagers. Finally, we report the genome sequences of 13 SARS-CoV-2 isolates circulating in Burkina Faso at the time of analysis, assigned to lineages: A.19, A.21, B.1.1.404, B.1.1.118, B.1 and grouped into clades; 19B, 20A and 20B. This is the first population-based study about SARS-CoV-2 and malaria in Burkina Faso during the first wave of the pandemic, providing a relevant estimation of the real prevalence of SARS-CoV-2 and variants circulating in this Sub-Saharan African country. Besides, it highlights the low frequency of co-infection with malaria in African communities.This research work received funding from by the European Commission NextGenerationEU (Regulation EU 2020/2094) and grant 202020E159 through CSIC Global Health Platform (PTI Salud Global).N

Aplicaciones de la secuenciación del genoma completo de Mycobacterium tuberculosis para la predicción de resistencias a antibióticos en muestras de Mozambique

Trabajo presentado a las XXVII Jornadas Internacionales sobre Tuberculosis celebradas en Barcelona del 13 al 14 de noviembre de 2023.Peer reviewe

Genetic variability of hepatitis C virus before and after combined therapy of interferon plus ribavirin

We present an analysis of the selective forces acting on two hepatitis C virus genome regions previously postulated to be involved in the viral response to combined antiviral therapy. One includes the three hypervariable regions in the envelope E2 glycoprotein, and the other encompasses the PKR binding domain and the V3 domain in the NS5A region. We used a cohort of 22 non-responder patients to combined therapy (interferon alpha-2a plus ribavirin) for which samples were obtained before initiation of therapy and after 6 or/and 12 months of treatment. A range of 25-100 clones per patient, genome region and time sample were sequenced. These were used to detect general patterns of adaptation, to identify particular adaptation mechanisms and to analyze the patterns of evolutionary change in both genome regions. These analyses failed to detect a common adaptive mechanism for the lack of response to antiviral treatment in these patients. On the contrary, a wide range of situations were observed, from patients showing no positively selected sites to others with many, and with completely different topologies in the reconstructed phylogenetic trees. Altogether, these results suggest that viral strategies to evade selection pressure from the immune system and antiviral therapies do not result from a single mechanism and they are likely based on a range of different alternatives, in which several different changes, or their combination, along the HCV genome confer viruses the ability to overcome strong selective [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]

Genomic analyses of Mycobacterium tuberculosis from human lung resections reveal a high frequency of polyclonal infections

11 páginas, 5 figuras, 1 tablaPolyclonal infections occur when at least two unrelated strains of the same pathogen are detected in an individual. This has been linked to worse clinical outcomes in tuberculosis, as undetected strains with different antibiotic resistance profiles can lead to treatment failure. Here, we examine the amount of polyclonal infections in sputum and surgical resections from patients with tuberculosis in the country of Georgia. For this purpose, we sequence and analyse the genomes of Mycobacterium tuberculosis isolated from the samples, acquired through an observational clinical study (NCT02715271). Access to the lung enhanced the detection of multiple strains (40% of surgery cases) as opposed to just using a sputum sample (0-5% in the general population). We show that polyclonal infections often involve genetically distant strains and can be associated with reversion of the patient's drug susceptibility profile over time. In addition, we find different patterns of genetic diversity within lesions and across patients, including mutational signatures known to be associated with oxidative damage; this suggests that reactive oxygen species may be acting as a selective pressure in the granuloma environment. Our results support the idea that the magnitude of polyclonal infections in high-burden tuberculosis settings is underestimated when only testing sputum samples.The authors were supported by projects SAF2016-77346-R and PID2019-104477RB-I00 awarded to IC and the grant BES-2017-079656 awarded to MM by the Spanish Ministry of Economy and Competitiveness and Ministry of Science, the ERC project 638553-TBACCELERATE awarded to IC, Spanish Government-FEDER Funds through CV contract CPII18/00031 and grant PI16/01511, and Generalitat Valencia Grant to I.C. (code PROMETEO/2020/012). The grant providers played no part in study design, data collection, and analysis, or the preparation of the manuscript.Peer reviewe

Genomic determinants associated with SARS-CoV-2 virulence

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.Peer reviewe

Deciphering the tangible spatio-temporal spread of a 25 years tuberculosis outbreak boosted by social determinants

Background. Outbreak strains are good candidates to look for intrinsic transmissibility as they are responsible for a large number of cases with sustained transmission. However, assessment of the success of long-lived outbreak strains has been flawed by the use of low-resolution typing methods and restricted geographical investigations. We now have the potential to address the nature of outbreak strains by combining large genomic datasets and phylodynamic approaches. Methods. We retrospectively sequenced the whole genome of representative samples assigned to an outbreak circulating in the Canary Islands (GC) since 1993; accounting for ~20% of local TB cases. We selected a panel of specific SNP markers to in-silico search for additional outbreak related sequences within publicly-available TB genomic data. Using this information we inferred the origin, spread and epidemiological parameters of the GC-outbreak. Findings. Our approach allowed us to accurately trace both the historical and recent dispersion of the strain. We evidenced its high success within the Canarian archipelago but found a limited expansion abroad. Estimation of epidemiological parameters from genomic data contradicts a distinct biology of the GC-strain. Interpretation. With the increasing availability of genomic data allowing for an accurate inference of strain spread and key epidemiological parameters, we can now revisit the link between Mycobacterium tuberculosis genotypes and transmission, as routinely done for SARS-CoV-2 variants of concern. We show that the success of the GC-strain is better explained by social determinants rather than intrinsically higher bacterial transmissibility. Our approach can be used to trace and characterize strains of interest worldwide.This study was founded by Instituto de Salud Carlos III (FIS18/0336), Gobierno de Aragon/Fondo Social Europeo Construyendo Europa desde Aragon to SS. European Research Council (101001038-TB-RECONNECT), the Ministerio de Economía, Industria y Competividad (PID2019-104477RB-I00) to IC.N