Development of rapid and cost-effective top-loading device for the detection of anti-SARS-CoV-2 IgG/IgM antibodies

Infection with SARS-CoV-2, the Betacoronavirus, caused a pandemic that affected the globe negatively. The gold method, RT-PCR, can detect SARS-CoV-2 but it is time-consuming and needs sophisticated equipment and professional personnel. On the other hand, rapid tests offer fast results and can detect anti-SARS-CoV-2 antibodies (Abs). The aim of this study is to develop a new rapid and cost-effective method for the detection of anti-SARS-CoV-2 IgG/IgM Abs. A new top-loading detection device was developed and composed of a small piece of plastic (25 × 25 × 0.5 mm) with an opening in the center, a piece of nitrocellulose (NC) membrane enough to block the opening from one side and adhesive tape to affix the NC to the plastic piece. The NC is blotted with anti-human IgG/IgM and rabbit serum. The device was evaluated against a commercially available IgG/IgM ELISA detection kit using normal, Covid-19-positive, HCV, HBV, and Cytomegalovirus-positive sera. Outcomes demonstrated simplicity, reproducibility, and accuracy of the new device and results can be obtained in less than 5 min. We anticipate our developed assay method to be used widely in point of care before deciding on the use of expensive nucleic acid assays.

Diagnosis of SARS-Cov-2 Infection by RT-PCR Using Specimens Other Than Naso- and Oropharyngeal Swabs: A Systematic Review and Meta-Analysis

The rapid and accurate testing of SARS-CoV-2 infection is still crucial to mitigate, and eventually halt, the spread of this disease. Currently, nasopharyngeal swab (NPS) and oropharyngeal swab (OPS) are the recommended standard sampling techniques, yet, these have some limitations such as the complexity of collection. Hence, several other types of specimens that are easier to obtain are being tested as alternatives to nasal/throat swabs in nucleic acid assays for SARS-CoV-2 detection. This study aims to critically appraise and compare the clinical performance of RT-PCR tests using oral saliva, deep-throat saliva/posterior oropharyngeal saliva (DTS/POS), sputum, urine, feces, and tears/conjunctival swab (CS) against standard specimens (NPS, OPS, or a combination of both). In this systematic review and meta-analysis, five databases (PubMed, Scopus, Web of Science, ClinicalTrial.gov and NIPH Clinical Trial) were searched up to the 30th of December, 2020. Case-control and cohort studies on the detection of SARS-CoV-2 were included. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS 2). We identified 1560 entries, 33 of which (1.1%) met all required criteria and were included for the quantitative data analysis. Saliva presented the higher accuracy, 92.1% (95% CI: 70.0–98.3), with an estimated sensitivity of 83.9% (95% CI: 77.4–88.8) and specificity of 96.4% (95% CI: 89.5–98.8). DTS/POS samples had an overall accuracy of 79.7% (95% CI: 43.3–95.3), with an estimated sensitivity of 90.1% (95% CI: 83.3–96.9) and specificity of 63.1% (95% CI: 36.8–89.3). The remaining index specimens could not be adequately assessed given the lack of studies available. Our meta-analysis shows that saliva samples from the oral region provide a high sensitivity and specificity; therefore, these appear to be the best candidates for alternative specimens to NPS/OPS in SARS-CoV-2 detection, with suitable protocols for swab-free sample collection to be determined and validated in the future. The distinction between oral and extra-oral salivary samples will be crucial, since DTS/POS samples may induce a higher rate of false positives. Urine, feces, tears/CS and sputum seem unreliable for diagnosis. Saliva testing may increase testing capacity, ultimately promoting the implementation of truly deployable COVID-19 tests, which could either work at the point-of-care (e.g. hospitals, clinics) or at outbreak control spots (e.g., schools, airports, and nursing homes).

The Promise of Aggregation-Induced Emission Luminogens for Detecting COVID-19

The long-term pandemic of coronavirus disease 2019 (COVID-19) requires sensitive and accurate diagnostic assays to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus and SARS-CoV-2 antibodies in infected individuals. Currently, RNA of SARS-CoV-2 virus is mainly detected by reverse transcription-polymerase chain reaction (RT-PCR)-based nucleic acid assays, while SARS-CoV-2 antigen and antibody are identified by immunological assays. Both nucleic acid assays and immunological assays rely on the luminescence signals of specific luminescence probes for qualitative and quantitative detection. The exploration of novel luminescence probes will play a crucial role in improving the detection sensitivity of the assays. As innate probes, aggregation-induced emission (AIE) luminogens (AIEgens) exhibit negligible luminescence in the free state but enhanced luminescence in the aggregated or restricted states. Moreover, AIEgen-based nanoparticles (AIE dots) offer efficient luminescence, good biocompatibility and water solubility, and superior photostability. Both AIEgens and AIE dots have been widely used for high-performance detection of biomolecules and small molecules, chemical/biological imaging, and medical therapeutics. In this review, the availability of AIEgens and AIE dots in nucleic acid assays and immunological assays are enumerated and discussed. By building a bridge between AIE materials and COVID-19, we hope to inspire researchers to use AIE materials as a powerful weapon against COVID-19.

Point of Care Diagnostic Devices for Rapid Detection of Novel Coronavirus (SARS-nCoV19) Pandemic: A Review

Coronaviruses are recognized as causative agents of human diseases worldwide. In Wuhan, China, an outbreak of Severe acute respiratory syndrome novel Coronavirus (SARS-nCoV-2) was reported at the end of December 2019, causing 63 million COVID cases and 1.3 million deaths globally by 2 December, 2020. The transmission risk forecasts and the SARS-nCoV-2 epidemic pattern are progressive. Unfortunately, there is no specific FDA approved drugs or vaccines available currently to treat SARS-nCoV-2. In response to nCoV-2 spread, the rapid detection is crucial for estimating the severity of the disease and treatment of patients. Currently, there are several RT-PCR based diagnostic kits available for SARS-nCoV-2 detection, which are time-consuming, expensive, need advanced equipment facilities and trained personnel. The cost of diagnosis and the unavailability of sufficient test kits may prevent to check community transmission. Furthermore, expanding the testing facilities in asymptomatic cases in hotspots require more Point of Care (PoC) devices. Therefore, fast, inexpensive, and reliable methods of detection of SARS-nCoV-2 virus infection in humans is urgently required. The rapid and easy-to-use devices will facilitate onsite testing. In this review, nucleic acid assays, serological assays, multiplex assays, and PoC devices are discussed to understand various diagnostic approaches to reduce the spread and mortality rate in the future. Aptamer based detection is most specific, inexpensive and rapid detection of SARS-nCoV-2 without laboratory tools. To the best of our knowledge more than 900 SARS-nCoV-2 test kits are in pipeline, among 395 test kits are molecular bested test kits and only few test kits are developed using Aptamer technology https://www.finddx.org/covid-19/pipeline/.

Efficient design of maximally active and specific nucleic acid diagnostics for thousands of viruses

Harnessing genomic data and predictive models will provide activity-informed diagnostic assays for thousands of viruses and offer rapid design for novel ones. Here we develop and extensively validate new algorithms that design nucleic acid assays having maximal predicted detection activity over a virus’s full genomic diversity with stringent specificity. Focusing on CRISPR-Cas13a detection, we test a library of ~ 19,000 guide-target pairs and construct a convolutional neural network that predicts Cas13a detection activity better than other techniques. We link our methods by building ADAPT, an end-to-end system that automatically leverages the latest viral genome data. We designed optimal species-specific assays for the 1,933 vertebrate-infecting viral species within 2 hours for most species and 24 hours for all but 3. ADAPT’s designs are sensitive and specific down to the lineage-level for the range of taxa we tested, including ones that pose challenges involving genomic diversity and specificity. They also exhibit significantly higher fluorescence and lower limits of detection, across a virus’s full spectrum of genomic diversity, than designs from standard techniques. ADAPT is available in an accessible software package and can be applied to other detection technologies to enhance critically-needed viral diagnostic and surveillance efforts.

Is it necessary for suspected children with coronavirus disease-2019(COVID-19) to perform CT scan?

Objectives: the aim is to evaluate justification for suspected children withcoronavirus disease-2019 (COVID-19) to perform CT scanning. Methods: Eighteen suspected children (7 male and 11 female) accepted both CT scanning (except one) and then pharyngeal swab assays from 26th January to 9th March 2020 in the retrospective study. They were confirmed COVID-19 by twice positive test and divided into two groups: asymptomatic subgroup and symptomatic subgroup. Fisher`s exact test was used in statistical analysis. Results: The CT positive ratio was not significant in the two subgroups (0 (0%) vs 3 (23.1%), p=0.541), the same as that in different sex and ages (female vs male: 2 (20.0%) vs 1 (14.3%), p=1.000; <=3 years vs >3 years: 2 (28.6%) vs 1 (10.0%), p=0.537). The demonstrations of the two positive CT were multiple patchy infiltration or ill-fined ground-glass opacity in subpleural regions. Conclusions: It was unnecessary for suspected children with COVID-19 to perform CT scanning as a “routine” ahead of viral nucleic acid assays.