Interferon-γ release assays (IGRA) with Resuscitation promoting factor (Rpf) proteins enhanced tuberculosis (TB) screening and diagnosis in adults but have not been evaluated in children. Children ...often develop paucibacillary TB and their immune response differs from that of adults, which together affect TB disease diagnostics and immunodiagnostics. We assessed the ability of Rpf to identify infection among household TB-exposed children in The Gambia and investigated their ability to discriminate Mycobacterium tuberculosis complex (MTBC) infection from active TB disease in children.
Detailed clinical investigations were done on 93 household TB-exposed Gambian children and a tuberculin skin test (TST) was administered to asymptomatic children. Venous blood was collected for overnight stimulation with ESAT-6/CFP-10-fusion protein (EC), purified protein derivative and RpfA, B, C, D and E. Interferon gamma (IFN-γ) production was measured by ELISA in supernatants and corrected for the background level. Infection status was defined by IGRA with EC and TB disease by mycobacterial confirmation and/or clinical diagnosis. We compared IFN-γ levels between infected and uninfected children and between infected and TB diseased children using a binomial logistic regression model while correcting for age and sex. A Receiver Operating Characteristics analysis was done to find the best cut-off for IFN-γ level and calculate sensitivity and specificity.
Interferon gamma production was significantly higher in infected (IGRA+, n = 45) than in uninfected (IGRA-, n = 20) children after stimulation with RpfA, B, C, and D (P = 0.03; 0.007; 0.03 and 0.003, respectively). Using RpfB and D-specific IFN-γ cut-offs (33.9 pg/mL and 67.0 pg/mL), infection was classified with a sensitivity-specificity combination of 73-92% and 77-72% respectively, which was similar to and better than 65-75% for TST. Moreover, IFN-γ production was higher in infected than in TB diseased children (n = 28, 5 bacteriologically confirmed, 23 clinically diagnosed), following RpfB and D stimulation (P = 0.02 and 0.03, respectively).
RpfB and RpfD show promising results for childhood MTBC infection screening, and both performed similar to and better than the TST in our study population. Additionally, both antigens appear to discriminate between infection and disease in children and thus warrant further investigation as screening and diagnostic antigens for childhood TB.
The epidemiology of Mycobacterium tuberculosis (Mtb) and M. africanum (Maf) suggests differences in their virulence, but the host immune profile to better understand the pathogenesis of tuberculosis ...(TB) have not been studied. We compared the transcriptomic and metabolic profiles between Mtb- and Maf-infected TB cases to identify host biomarkers associated with lineages-specific pathogenesis and response to anti-TB chemotherapy. Venous blood samples from Mtb- and Maf-infected patients obtained before and after anti-TB treatment were analyzed for cell composition, gene expression and metabolic profiles. Prior to treatment, similar transcriptomic profiles were seen in Maf- and Mtb-infected patients. In contrast, post treatment, over 1600 genes related to immune responses and metabolic diseases were differentially expressed between the groups. Notably, the upstream regulator hepatocyte nuclear factor 4-alpha (HNF4α), which regulated 15% of these genes, was markedly enriched. Serum metabolic profiles were similar in both group pre-treatment, but the decline in pro-inflammatory metabolites post treatment were most pronounced in Mtb-infected patients. Together, the differences in both peripheral blood transcriptomic and serum metabolic profiles between Maf- and Mtb-infected patients observed over the treatment period, might be indicative of intrinsic host factors related to susceptibility to TB and/or differential efficacy of the standard anti-TB treatment on the two lineages.
Around 10% of the coding potential of
is constituted by two poorly understood gene families, the
and
loci, thought to be involved in host-pathogen interactions. Their repetitive nature and high GC ...content have hindered sequence analysis, leading to exclusion from whole-genome studies. Understanding the genetic diversity of
families is essential to facilitate their potential translation into tools for tuberculosis prevention and treatment.
To investigate the genetic diversity of the 169
/
genes, we performed a sequence analysis across 73 long-read assemblies representing seven different lineages of
and
BCG. Individual
gene alignments were extracted and diversity and conservation across the different lineages studied.
The
/
genes were classified into three groups based on the level of protein sequence conservation relative to H37Rv, finding that >50% were conserved, with indels in
and
sub-families being major drivers of structural variation. Gene rearrangements, such as duplications and gene fusions, were observed between
and
genes. Inter-lineage diversity revealed lineage-specific SNPs and indels.
The high level of
genes conservation, together with the lineage-specific findings, suggest their phylogenetic informativeness. However, structural variants and gene rearrangements differing from the reference were also identified, with potential implications for pathogenicity. Overall, improving our knowledge of these complex gene families may have insights into pathogenicity and inform the development of much-needed tools for tuberculosis control.
Summary Background Diagnosis of tuberculosis (TB) remains difficult, particularly in resource-limited settings. The development of nucleic acid-based tests for detection of Mycobacterium tuberculosis ...complex (MTBC) has significantly increased sensitivity compared to conventional smear microscopy and provides results within a matter of hours compared to weeks for the current gold-standard, liquid culture. Methods In this study we performed side-by-side comparison of mycobacterial detection assays on sputum samples from 285 subjects presenting with symptoms suggestive of TB in The Gambia and a cross-sectional cohort of 156 confirmed TB patients with a median of 2 months of treatment. A novel assay, Loop-Mediated Amplification test for TB (TB-LAMP), was compared to smear microscopy, MGIT culture and GeneXpert MTB/RIF for all samples. Results When culture was used as the reference standard, we found an overall sensitivity for TB-LAMP of 99% (95% CI: 94.5–99.8) and specificity of 94% (95% CI: 89.3–96.7). When latent class analysis was performed, TB-LAMP had 98.6% (95% CI: 95.9–100) sensitivity and 99% (95% CI: 98.2–100) specificity compared to 91.1% (95% CI: 86.1–96) sensitivity and 100% (95% CI: 98.2–100) specificity for MGIT culture. GeneXpert had the highest sensitivity 99.1% (95% CI: 97.1–100) but the lowest specificity 96% (95% CI: 92.6–98.3). Both TB-LAMP and GeneXpert showed high sensitivity and specificity regardless of age or strain of infection. Conclusion Our findings show the diagnostic utility of both GeneXpert and TB-LAMP in The Gambia. Whilst TB-LAMP requires less infrastructure, it is unable to detect drug-resistant patterns and therefore would be most suitable as a screening test for new TB cases in peripheral health clinics.
Serotype 24F is one of the emerging pneumococcal serotypes after the introduction of pneumococcal conjugate vaccine (PCV). We aimed to identify lineages driving the increase of serotype 24F in France ...and place these findings into a global context.
Whole-genome sequencing was performed on a collection of serotype 24F pneumococci from asymptomatic colonisation (n=229) and invasive disease (n=190) isolates among individuals younger than 18 years in France, from 2003 to 2018. To provide a global context, we included an additional collection of 24F isolates in the Global Pneumococcal Sequencing (GPS) project database for analysis. A Global Pneumococcal Sequence Cluster (GPSC) and a clonal complex (CC) were assigned to each genome. Phylogenetic, evolutionary, and spatiotemporal analysis were conducted using the same 24F collection and supplemented with a global collection of genomes belonging to the lineage of interest from the GPS project database (n=25 590).
Serotype 24F was identified in numerous countries mainly due to the clonal spread of three lineages: GPSC10 (CC230), GPSC16 (CC156), and GPSC206 (CC7701). GPSC10 was the only multidrug-resistant lineage. GPSC10 drove the increase in 24F in France and had high invasive disease potential. The international dataset of GPSC10 (n=888) revealed that this lineage expressed 16 other serotypes, with only six included in 13-valent PCV (PCV13). All serotype 24F isolates were clustered in a single clade within the GPSC10 phylogeny and long-range transmissions were detected from Europe to other continents. Spatiotemporal analysis showed GPSC10-24F took 3-5 years to spread across France and a rapid change of serotype composition from PCV13 serotype 19A to 24F during the introduction of PCV13 was observed in neighbouring country Spain.
Our work reveals that GPSC10 alone is a challenge for serotype-based vaccine strategy. More systematic investigation to identify lineages like GPSC10 will better inform and improve next-generation preventive strategies against pneumococcal diseases.
Bill & Melinda Gates Foundation, Wellcome Sanger Institute, and the US Centers for Disease Control and Prevention.
Mycobacterium tuberculosis strains collected from patients with pulmonary tuberculosis in the West and Centre regions of Cameroon were culture-tested for the major anti-tuberculosis drugs (isoniazid, ...rifampicin, ethambutol and streptomycin). Of the 112 predetermined samples included in the study, 21 (18.7%) were sensitive to all the drugs, while 91 (81.3%) were resistant to at least one drug. Resistance to isoniazid was the most common (79.1%), followed by rifampicin (65.9%), streptomycin (62.6%) and ethambutol (38.5%), 50% of the samples were qualified as (resistant to at least isoniazid and rifampicin). A PCR-based dot-blot hybridization strategy was used to detect mutations at different loci in five genes associated with resistance to the drugs tested. For rifampicin resistance, the mutation on codon 526 of the rpoB gene was the most common (66.3%), followed by the codon 516 (60.5%) and the codon 531 (31.4%). The mutation on codon 513 of the rrs gene was the most encountered in streptomycin resistant strains (77.8%); while the mutation on codon 43 of rpsL gene was always associated to that of rrs gene. The mutation on codon 531 of the rpoB gene for rifampicin resistance (95.6%) was most prevalent in the samples from the Centre region compared to the West region (P = 0.0003). Generally, no significant differences were obtained on the prevalences of the other mutations analysed based on the regions, gender or the age of patients (P > 0.05). The dot-blot analysis, gave no result for the codon 306 of embB gene associated with ethambutol resistance under experimental conditions used in this study. The PCR-based dot-blot hybridization strategy was tested to validate the procedure on stored samples and could be a good surveillance method for rapid detection of the evolution of drug resistant M. tuberculosis in Cameroon.
Pneumococcal disease outbreaks of vaccine preventable serotype 4 sequence type (ST)801 in shipyards have been reported in several countries. We aimed to use genomics to establish any international ...links between them.
Sequence data from ST801-related outbreak isolates from Norway (n = 17), Finland (n = 11) and Northern Ireland (n = 2) were combined with invasive pneumococcal disease surveillance from the respective countries, and ST801-related genomes from an international collection (n = 41 of > 40,000), totalling 106 genomes. Raw data were mapped and recombination excluded before phylogenetic dating.
Outbreak isolates were relatively diverse, with up to 100 SNPs (single nucleotide polymorphisms) and a common ancestor estimated around the year 2000. However, 19 Norwegian and Finnish isolates were nearly indistinguishable (0–2 SNPs) with the common ancestor dated around 2017.
The total diversity of ST801 within the outbreaks could not be explained by recent transmission alone, suggesting that harsh environmental and associated living conditions reported in the shipyards may facilitate invasion of colonising pneumococci. However, near identical strains in the Norwegian and Finnish outbreaks does suggest that transmission between international shipyards also contributed to those outbreaks. This indicates the need for improved preventative measures in this working population including pneumococcal vaccination.
Aerial yam (Dioscorea bulbifera L.) is a crop of great economic importance and an excellent candidate for improving food security in developing countries. Understanding the genetic variability of any ...crop species is a decisive step for its improvement and requires characterization and evaluation of available germplasm. The objectives of this study were to determine the extent of genetic variability, estimate the association between agromorphological traits and clustering among 57 genotypes of aerial yam from three distinct agro-ecological zones in Cameroon using multivariate analysis. Thirty nine characters (23 qualitative and 16 quantitative) were used for the study. Significant differences in genetic diversity indices were found. Accessions from the bimodal humid forest zone (Na = 2.08, He = 0.27) showed significantly lower diversity compared to both western highland (Na = 2.30, He = 0.34) and humid monomodal forest zones (Na = 2.57, He = 0.32). Means values of most quantitative traits also showed significant differences between agro-ecological zones. Batingla-3 and Bawouwoua-1 had important bulbil yield, reaching 3500 g / plant. Significant associations were found between many traits. The use of the Unweighted Pair Group Method with Arithmetic Mean allowed the distribution of the 57 genotypes into six distinct clusters with the clustering pattern not showing any parallelism with location sites or agro-ecological zones. Mahalanobis D2 statistics revealed the highest inter-cluster distance between cluster II and VI. Accessions of these clusters are potential parents for future breeding programs. This study showed that aerial yam from Cameroon has an enormous wealth of traits variation, indicating huge potential for its genetic improvement through selection and hybridization.
An experiment was conducted to evaluate the effect of graded levels of Chromolaena odorata leaf meal (COLM) on production performance, egg quality characteristics, and serum biochemical parameters on ...Brahma laying hens. A total of forty-five local laying hens aged 4 to 5 months were weighed and assigned to three treatment groups in a completely randomized design. COLM was used as a supplement and incorporated into the diets at 0, 1, and 2% in diets T0, T1, and T2 respectively. Data were collected on production performance, egg quality characteristics, and serum biochemistry. Results from the study indicate that body weight gain, average weight, and egg volume were low (p<0.05) with treatment T2 compared to control (T0) and the best was obtained with treatment T1. The Haugh unit and percentage hen day production were not negatively affected by the treatment levels of COLM. There were significant (p<0.05) differences in triglyceride, total cholesterol, and urea. Results obtained from this study revealed that the inclusion of 1% of COLM improved the egg quality as well as the health status of the birds without having any detrimental effect on the birds.
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