8 research outputs found

    The global inequity of COVID-19 diagnostics : challenges and opportunities

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    Diagnostics for COVID-19 have advanced at an unprecedented pace over the last two years. Testing is a critical pillar of pandemic control, and is required for epidemiological tracking, treatment, and surveillance. Despite high quality SARS-CoV-2 viral diagnostic capability, there are vast global inequities in access. The Virology, Immunology, and Diagnostics Working Group(WG) of the COVID-19 Clinical Research Coalition (CRC) brings together experts in immunology, infectious diseases, and microbiology to advocate for equity-based COVID-19 research, prioritising solutions driven by communities in low-income and lower middle-income countries (LMICs).1 This commentary shares the unique perspective of the WG on the asymmetry in COVID-19 diagnostic access between low-income and high-income settings, the barriers to these disparities, and highlights opportunities to remedy these inequities.PostprintPeer reviewe

    Cloning, expression, purification and characterization of a DsbA-like protein from Wolbachia pipientis

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    Wolbachia pipientis are obligate endosymbionts that infect a wide range of insect and other arthropod species. They act as reproductive parasites by manipulating the host reproduction machinery to enhance their own transmission. This unusual phenotype is thought to be a consequence of the actions of secreted Wolbachia proteins that are likely to contain disulfide bonds to stabilize the protein structure. In bacteria, the introduction or isomerization of disulfide bonds in proteins is catalyzed by Dsb proteins. The Wolbachia genome encodes two proteins, a-DsbA1 and a-DsbA2, that might catalyze these steps. In this work we focussed on the 234 residue protein a-DsbA1; the gene was cloned and expressed in Escherichia coli, the protein was purified and its identity confirmed by mass spectrometry. The sequence identity of a-DsbA1 for both dithiol oxidants(E. coli DsbA, 12%) and disulfide isomerases(E. coli DsbC, 14%) is similar. We therefore sought to establish whether a-DsbA1 is an oxidant or an isomerase based on functional activity. The purified a-DsbA1 was active in an oxidoreductase assay but had little isomerase activity, indicating that a-DsbA1 is DsbA-like rather than DsbC-like. This work represents the first successful example of the characterization of a recombinant Wolbachia protein. Purified a-DsbA1 will now be used in further functional studies to identify protein substrates that could help explain the molecular basis for the unusual Wolbachia phenotypes, and in structural studies to explore its relationship to other disulfide oxidoreductase proteins. Copyright © 2008 Elsevier In

    Robust estimation of bacterial cell count from optical density

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    Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

    Identifying the necessary capacities for the adaptation of a diabetes phenotyping algorithm in countries of differing economic development status

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    Background In 2019, the World Health Organization recognised diabetes as a clinically and pathophysiologically heterogeneous set of related diseases. Little is currently known about the diabetes phenotypes in the population of low- and middle-income countries (LMICs), yet identifying their different risks and aetiology has great potential to guide the development of more effective, tailored prevention and treatment. Objectives This study reviewed the scope of diabetes datasets, health information ecosystems, and human resource capacity in four countries to assess whether a diabetes phenotyping algorithm (developed under a companion study) could be successfully applied. Methods The capacity assessment was undertaken with four countries: Trinidad, Malaysia, Kenya, and Rwanda. Diabetes programme staff completed a checklist of available diabetes data variables and then participated in semi-structured interviews about Health Information System (HIS) ecosystem conditions, diabetes programme context, and human resource needs. Descriptive analysis was undertaken. Results Only Malaysia collected the full set of the required diabetes data for the diabetes algorithm, although all countries did collect the required diabetes complication data. An HIS ecosystem existed in all settings, with variations in data hosting and sharing. All countries had access to HIS or ICT support, and epidemiologists or biostatisticians to support dataset preparation and algorithm application. Conclusions Malaysia was found to be most ready to apply the phenotyping algorithm. A fundamental impediment in the other settings was the absence of several core diabetes data variables. Additionally, if countries digitise diabetes data collection and centralise diabetes data hosting, this will simplify dataset preparation for algorithm application. These issues reflect common LMIC health systems’ weaknesses in relation to diabetes care, and specifically highlight the importance of investment in improving diabetes data, which can guide population-tailored prevention and management approaches