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Nat Commun ; 12(1): 6610, 2021 11 16.
Article in English | MEDLINE | ID: covidwho-1521737


COVID-19 typically manifests as a respiratory illness, but several clinical reports have described gastrointestinal symptoms. This is particularly true in children in whom gastrointestinal symptoms are frequent and viral shedding outlasts viral clearance from the respiratory system. These observations raise the question of whether the virus can replicate within the stomach. Here we generate gastric organoids from fetal, pediatric, and adult biopsies as in vitro models of SARS-CoV-2 infection. To facilitate infection, we induce reverse polarity in the gastric organoids. We find that the pediatric and late fetal gastric organoids are susceptible to infection with SARS-CoV-2, while viral replication is significantly lower in undifferentiated organoids of early fetal and adult origin. We demonstrate that adult gastric organoids are more susceptible to infection following differentiation. We perform transcriptomic analysis to reveal a moderate innate antiviral response and a lack of differentially expressed genes belonging to the interferon family. Collectively, we show that the virus can efficiently infect the gastric epithelium, suggesting that the stomach might have an active role in fecal-oral SARS-CoV-2 transmission.

COVID-19/pathology , Intestinal Mucosa/virology , Organoids/virology , SARS-CoV-2/physiology , Stomach/virology , Virus Replication/physiology , Aborted Fetus , Aged , Animals , COVID-19/virology , Cell Line , Child , Child, Preschool , Chlorocebus aethiops , Humans , Infant , Intestinal Mucosa/pathology , Middle Aged , Organoids/pathology , SARS-CoV-2/isolation & purification , Stomach/pathology
chemRxiv; 2021.
Preprint in English | ChemRxiv | ID: ppcovidwho-291445


SARS-CoV-2 diagnostic practices broadly involve either qPCR based nucleic amplification or lateral flow assays (LFAs). qPCR based techniques suffer from the disadvantage of requiring thermal cycling (difficult to implement for low-cost field use) leading to limitation on sample to answer time, the potential to amplify viral RNA sequences after a person is no longer infectious and being reagent intense. LFA performance is restricted by qualitative or semi-quantitative readouts, limits on sensitivity and poor reproducibility. Electrochemical biosensors, and particularly glucose test strips, present an appealing platform for development of biosensing solutions for SARS-CoV-2 as they can be multiplexed and implemented at very low cost at point of use with high sensitivity and quantitative digital readout. This work reports the successful raising of an Opti-mer sequence for the spike protein of SARS-CoV-2 and then development of an impedimetric biosensor which utilises thin film gold sensors on low-cost laminate substrates from home blood glucose monitoring. Clinically relevant detection levels for SARS-CoV-2 are achieved in a simple, label-free measurement format using sample incubation times of 15 minutes. The biosensor developed here is compatible with mass manufacture, is sensitive and low-cost CE marked readout instruments already exist. These findings pave the way to a low cost and mass manufacturable test with the potential to overcome the limitations associated with current technologies.

chemRxiv; 2020.
Preprint in English | ChemRxiv | ID: ppcovidwho-3210


Emerging in late 2019, the SARS-CoV-2 virus has had a devastating health and economic effects around the world forcing governments to enact restrictions on day to day life, resulting in severe economic and social disruption. The virus has stimulated new research in the fields of drug development, vaccinology and diagnostic testing. Here we present the basis for a simple, mass manufacturable saliva based electrochemical assay for the SARS-CoV-2 virus acheived through adsorption of the Angiotsnsin Converting Enzyme 2 (ACE2) into thiolated amphiphobic prefluoro monolayer assemled on a gold sensor surface. Following sensor preparation, it is possible to measure specific binding of recombinant spike protein and discriminate positive and negative samples of inactivated SARS-CoV-2 following 30 minutes incubation under ambient conditions. Representative calculations of limits of detection are made for recombinant spike protein (1.68 ng/ml) and inactivated virus (37.8 dC/mL). The assay as presented ultimately shows discrimination between positive and negative inactivated SARS-CoV-2 samples originating from clinical molecular standards kit intended for clinical and biomedical assay validation, and which is designed to mimic clinical samples through presence of cells and proteins in the sample medium. The simple design of the label free measurement and the selection of reagents involved means the assay has clear potential for transfer onto mass producible units such as screen-printed electrodes similar to glucose-format test strips, to enable widespread, low cost and rapid testing for SARS-CoV-2 in the general population