9 results found
Crone M, Randell P, Herm Z, et al., 2021, Rapid design and implementation of an adaptive pooling workflow for SARS-CoV-2 testing in an NHS diagnostic laboratory: a proof-of-concept study, Wellcome Open Research, Vol: 6, Pages: 268-268
<ns4:p><ns4:bold>Background:</ns4:bold> Diagnostic laboratories are currently required to provide routine testing of asymptomatic staff and patients as a part of their clinical screening for SARS-CoV-2 infection. However, these cohorts display very different disease prevalence from symptomatic individuals and testing capacity for asymptomatic screening is often limited. Group testing is frequently proposed as a possible solution to address this; however, proposals neglect the technical and operational feasibility of implementation in a front-line diagnostic laboratory.</ns4:p><ns4:p> <ns4:bold>Methods: </ns4:bold>Between October and December 2020, as a seven-week proof of concept, we took into account scientific, technical and operational feasibility to design and implement an adaptive pooling strategy in an NHS diagnostic laboratory in London (UK). We assessed the impact of pooling on analytical sensitivity and modelled the impact of prevalence on pooling strategy. We then considered the operational constraints to model the potential gains in capacity and the requirements for additional staff and infrastructure. Finally, we developed a LIMS-agnostic laboratory automation workflow and software solution and tested the technical feasibility of our adaptive pooling workflow.</ns4:p><ns4:p> <ns4:bold>Results: </ns4:bold>First, we determined the analytical sensitivity of the implemented SARS-CoV-2 assay to be 250 copies/mL. We then determined that, in a setting with limited analyser capacity, the testing capacity could be increased by two-fold with pooling, however, in a setting with limited reagents, this could rise to a five-fold increase. These capacity increases could be realized with modest additional resource and staffing requirements whilst utilizing up to 76% fewer plastic consumables and 90% fewer reagents. Finally, we successfully implemented a plate-based pooling workflow and tested 920 patient
Rowan AG, May P, Badhan A, et al., 2021, Optimized protocol for a quantitative SARS-CoV-2 duplex RT-qPCR assay with internal human sample sufficiency control., Journal of Virological Methods, Vol: 294, Pages: 1-7, ISSN: 0166-0934
There is growing evidence that measurement of SARS-CoV-2 viral copy number can inform clinical and public health management of SARS-CoV-2 carriers and COVID-19 patients. Here we show that quantification of SARS-CoV-2 is feasible in a clinical setting, using a duplex RT-qPCR assay which targets both the E gene (Charité assay) and a human RNA transcript, RNase P (CDC assay) as an internal sample sufficiency control. Samples in which RNase P is not amplified indicate that sample degradation has occurred, PCR inhibitors are present, RNA extraction has failed or swabbing technique was insufficient. This important internal control reveals that 2.4% of nasopharyngeal swabs (15/618 samples) are inadequate for SARS-CoV-2 testing which, if not identified, could result in false negative results. We show that our assay is linear across at least 7 logs and is highly reproducible, enabling the conversion of Cq values to viral copy numbers using a standard curve. Furthermore, the SARS-CoV-2 copy number was independent of the RNase P copy number indicating that the per-swab viral copy number is not dependent on sampling- further allowing comparisons between samples. The ability to quantify SARS-CoV-2 viral copy number will provide an important opportunity for viral burden-guided public health and clinical decision making.
Crone MA, Priestman M, Ciechonska M, et al., 2020, A role for Biofoundries in rapid development and validation of automated SARS-CoV-2 clinical diagnostics (vol 11, 4464, 2020), NATURE COMMUNICATIONS, Vol: 11, ISSN: 2041-1723
Crone M, Priestman M, Ciechonska M, et al., 2020, A role for Biofoundries in rapid development and validation of automated SARS-CoV-2 clinical diagnostics, Nature Communications, Vol: 11, Pages: 1-11, ISSN: 2041-1723
The SARS-CoV-2 pandemic has shown how a rapid rise in demand for patient and community sample testing can quickly overwhelm testing capability globally. With most diagnostic infrastructure dependent on specialized instruments, their exclusive reagent supplies quickly become bottlenecks, creating an urgent need for approaches to boost testing capacity. We address this challenge by refocusing the London Biofoundry onto the development of alternative testing pipelines. Here, we present a reagent-agnostic automated SARS-CoV-2 testing platform that can be quickly deployed and scaled. Using an in-house-generated, open-source, MS2-virus-like particle (VLP) SARS-CoV-2 standard, we validate RNA extraction and RT-qPCR workflows as well as two detection assays based on CRISPR-Cas13a and RT-loop-mediated isothermal amplification (RT-LAMP). In collaboration with an NHS diagnostic testing lab, we report the performance of the overall workflow and detection of SARS-CoV-2 in patient samples using RT-qPCR, CRISPR-Cas13a, and RT-LAMP. The validated RNA extraction and RT-qPCR platform has been installed in NHS diagnostic labs, increasing testing capacity by 1000 samples per day.
Graham N, Junghans C, Downes R, et al., 2020, SARS-CoV-2 infection, clinical features and outcome of COVID-19 in United Kingdom nursing homes, Journal of Infection, Vol: 81, Pages: 411-419, ISSN: 0163-4453
OBJECTIVES: To understand SARS-Co-V-2 infection and transmission in UK nursing homes in order to develop preventive strategies for protecting the frail elderly residents. METHODS: An outbreak investigation involving 394 residents and 70 staff, was carried out in 4 nursing homes affected by COVID-19 outbreaks in central London. Two point-prevalence surveys were performed one week apart where residents underwent SARS-CoV-2 testing and had relevant symptoms documented. Asymptomatic staff from three of the four homes were also offered SARS-CoV-2 testing. RESULTS: Overall, 26% (95% CI 22 to 31) of residents died over the two-month period. All-cause mortality increased by 203% (95% CI 70 to 336) compared with previous years. Systematic testing identified 40% (95% CI 35 to 46) of residents as positive for SARS-CoV-2, and of these 43% (95% CI 34 to 52) were asymptomatic and 18% (95% CI 11 to 24) had only atypical symptoms; 4% (95% CI -1 to 9) of asymptomatic staff also tested positive. CONCLUSIONS: The SARS-CoV-2 outbreak in four UK nursing homes was associated with very high infection and mortality rates. Many residents developed either atypical or no discernible symptoms. A number of asymptomatic staff members also tested positive, suggesting a role for regular screening of both residents and staff in mitigating future outbreaks.
Kopniczky MB, Canavan C, McClymont DW, et al., 2020, Cell-free protein synthesis as a prototyping platform for mammalian synthetic biology, ACS Synthetic Biology, Vol: 9, Pages: 144-156, ISSN: 2161-5063
The field of mammalian synthetic biology is expanding quickly, and technologies for engineering large synthetic gene circuits are increasingly accessible. However, for mammalian cell engineering, traditional tissue culture methods are slow and cumbersome, and are not suited for high-throughput characterization measurements. Here we have utilized mammalian cell-free protein synthesis (CFPS) assays using HeLa cell extracts and liquid handling automation as an alternative to tissue culture and flow cytometry-based measurements. Our CFPS assays take a few hours, and we have established optimized protocols for small-volume reactions using automated acoustic liquid handling technology. As a proof-of-concept, we characterized diverse types of genetic regulation in CFPS, including T7 constitutive promoter variants, internal ribosomal entry sites (IRES) constitutive translation-initiation sequence variants, CRISPR/dCas9-mediated transcription repression, and L7Ae-mediated translation repression. Our data shows simple regulatory elements for use in mammalian cells can be quickly prototyped in a CFPS model system.
de Martín Garrido N, Crone MA, Ramlaul K, et al., 2020, Bacteriophage MS2 displays unreported capsid variability assembling T = 4 and mixed capsids, Molecular Microbiology, Vol: 113, Pages: 143-152, ISSN: 0950-382X
Bacteriophage MS2 is a positive-sense, single-stranded RNA virus encapsulated in an asymmetric T = 3 pseudo-icosahedral capsid. It infects Escherichia coli through the F-pilus, which it binds through a maturation protein incorporated into its capsid. Cryogenic electron microscopy has previously shown that its genome is highly ordered within virions, and that it regulates the assembly process of the capsid. In this study we have assembled recombinant MS2 capsids with non-genomic RNA containing the capsid incorporation sequence, and investigated the structures formed, revealing that T = 3, T = 4 and mixed capsids between these two triangulation numbers are generated, and resolving structures of T = 3 and T = 4 capsids to 4 Å and 6 Å respectively. We conclude that the basic MS2 capsid can form a mix of T = 3 and T = 4 structures, supporting a role for the ordered genome in favouring the formation of functional T = 3 virions.
<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Assessing transmission of SARS-CoV-2 by children in schools is of critical importance in informing public health action. Quantification of transmission by active contact tracing in children and their contacts can be practically challenging even in non-pandemic times.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Cases of COVID-19 in children in London schools were identified through statutory notification and matched to schools reporting cases. Bubble and non-bubble ‘control’ contacts at school and household contacts for each case were longitudinally sampled and tested for SARS-CoV2 using PCR. Surfaces and air in the home and school environment were also subject to longitudinal sampling and testing for SARS-CoV-2 for 21 days or 28 days.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Secondary transmission was not detected in 28 individual Bubble contacts, representing 10 distinct bubbles. Across the 8 non-bubble ‘school contact’ classes, 3/62 pupils tested positive – all three were asymptomatic and tested positive in one setting on the same day, unrelated to the original index case. In contrast the secondary attack rate in naïve household contacts of children was 14.5% and the inferred secondary attack rate was 25%. Environmental contamination with SARS-CoV-2 was rare in all schools studied, regardless of school type. This contrasted with contamination in households, where 20-30% of samples were positive.</jats:p></jats:sec><jats:sec><jats:title>Summary</jats:title><jats:p>The low levels of environmental contamination in schools are consistent with low transmission frequency and adequate levels of cleaning and ventilation in schools during the period of study. S
Guerra-Assunção JA, Randell PA, Boshier FAT, et al., Reliability of Spike Gene Target Failure for ascertaining SARS-CoV-2 lineage B.1.1.7 prevalence in a hospital setting
<jats:title>Abstract</jats:title><jats:p>The appearance of the SARS-CoV-2 lineage B.1.1.7 in the UK in late 2020, associated with faster transmission, sparked the need to find effective ways to monitor its spread. The set of mutations that characterise this lineage include a deletion in position 69 and 70 of the spike protein, which is known to be associated with Spike Gene Target Failure (SGTF) in a commonly used three gene diagnostic qPCR assay. The lower cost and faster turnaround times compared to whole genome sequencing make the use of qPCR for monitoring of the variant spread an attractive proposition. However, there are several potential issues with this approach. Here we use 826 SARS-CoV-2 samples collected in a hospital setting as part of the Hospital Onset COVID Infection (HOCI) study where qPCR was used for viral detection, followed by whole genome sequencing (WGS), to identify the factors to consider when using SGTF to infer lineage B.1.1.7 prevalence in a hospital setting, with potential implications for locations where this variant has recently been introduced.</jats:p>
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