Detection Of Coronavirus Research Articles

Alt solunum yolu enfeksiyonu olan köpeklerde canine coronavirusun tespiti ve moleküler karakterizasyonu

Coronaviridae familyasında yer alan coronaviruslar insan ve hayvanlarda sindirim ve solunum sistemi enfeksiyonlarına neden olmaktadır. Alfacoronavirus içerisinde yer alan canine coronaviruslar (CCoV)’ın CCoV I ve CCoV II olmak üzere iki alt tipi bulunmaktadır. CCoV-II ise CCoV- IIa ve IIb olmak üzere iki genotipe ayrılmaktadır. CCoV her yaştaki ve her türlü beslenme şekline sahip köpekleri etkilemesine rağmen özellikle yeni doğan yavrular daha duyarlı ve ciddi şekilde etkilenebilmektedir. Yapılan literatür araştırmalarına göre ülkemizde özellikle alt solunum yolu enfeksiyonlarındaki canine coronavirus varlığının tespitine yönelik moleküler çalışmalara rastlanılmamıştır. Bu çalışmada alt solunum yolu enfeksiyonu tanımlanan barınak köpeklerinde CCoV’un tespiti ve moleküler karakterizasyonunun yapılması amaçlandı. Bu amaçla alt solunum yolu enfeksiyonu tespit edilen 40 adet barınak köpeğinden alınan Bronkoalveolar Lavaj (BAL) sıvıları incelendi. Test edilen 40 köpeğe ait BAL sıvılarından 3 tanesinde CCoV tespit edildi. Yapılan dizin analizi sonrasında elde edilen dizinler ile filogenetik ağaç yapıldı. Filogenetik ağaçta pozitif bulunan 3 örnekten 2 sinin CCoV-I, bir örneğin ise CCoV-II olduğu tespit edildi. Sonuç olarak bu çalışma ile barınak köpeklerinin alt solunum yolu rahatsızlıklarında CCoV-I ve CCoV-II’ nin rol oynayabileceği ortaya konulmuştur. Ayrıca aynı barınakta farklı hayvanlarda iki farklı CCoV’nun tespiti önemli bir veri olarak değerlendirilmiş olup özellikle barınak koşulları gibi kalabalık ortamda barındırılan köpeklerdeki her iki tipin tespiti gelecekte oluşabilecek yeni varyantların ya da alt tiplerin oluşabilme ihtimalinin de göz ardı edilmemesi gerektiğini göstermektedir.

International multi-center evaluation of a rapid antigen test based on gold immunochromatographic assay for detection of severe acute respiratory syndrome coronavirus 2

Objective: The gold immunochromatographic assay for detection of SARS-CoV-2 antigen was evaluated by international multi-center clinical trial. Methods: A total of 1 855 clinical parallel samples with valid test results (for nucleic acid and antigen tests, respectively) were collected from nine countries, including Germany, the United Kingdom, Ukraine, France, India, Thailand, Malaysia, the United States of America and Brazil, with sampling period from January 3, 2021 to September 22, 2021. These samples were detected by SARS-CoV-2 antigen test kit (colloidal gold immunochromatography assay) and nucleic acid detection kit (real-time fluorescent quantitative reverse transcription polymerase chain reaction). Positive coincidence rates [(number of antigen-positive cases/nucleic acid-positive cases)×100%], negative coincidence rates [(number of antigen-negative cases/nucleic acid-negative cases)×100%], total coincidence rates [(number of cases with consistent results for both antigen and nucleic acid detection/number of total cases) ×100%], as well as Kappa values were calculated. The differences of the above indictors among different countries were evaluated by the coefficient of variation. The detection rates of the antigen test for samples with different cycle threshold values (Ct values) for the nucleic acid detection, different characteristics and different mutant strains were analyzed. Results: For all samples, the positive, negative, and total coincidence rate between the antigen test and nucleic acid assay was 90.8% (569/627), 99.7% (1 224/1 228) and 96.7% (1 793/1 855), respectively, and the consistency coefficient Kappa value was 0.924. Among these countries, the coefficient of variation for positive coincidence rates (except for Malaysia with a lot of samples with Ct value>30), negative coincidence rates (except for France without negative samples) and total coincidence rates (except for France) was 6%,<1%, and 6%, respectively. When Ct values were less than 25, the detection rates of antigen test were 83.3%-100% for each countries (the coefficient of variation was 6%); The total detection rate and the coefficient of variation was 93.4% (428/458) and 5%, respectively, for asymptomatic infected persons and cases within 7 days post onset of symptoms; the total detection rate for various SARS-CoV-2 mutant strains was 97.5% (119/122); and it showed negative results for samples from cases infected with other viruses, including influenza A virus subtype H1N1, influenza B virus, respiratory syncytial virus subgroups A and B, coxsackievirus 16, human metapneumovirus, parainfluenza virus types 1 and 4, Epstein-Barr virus and adenovirus. Conclusion: The SARS-CoV-2 antigen test kit showed excellent authenticity, and there were few differences for its indictors among nine countries, therefore it can meet the needs of large-scale early screening of SARS-CoV-2 infection.

Development and validation of a PCR-free nucleic acid testing method for RNA viruses based on linear molecular beacon probes

BackgroundRNA viruses periodically trigger pandemics of severe human diseases, frequently causing enormous economic losses. Here, a nucleic acid extraction-free and amplification-free RNA virus testing probe was proposed for the sensitive and simple detection of classical swine fever virus (CSFV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), based on a double-stranded molecular beacon method. This RNA virus probe contains two base sequences—a recognition strand that binds to the specific domain of CSFV N2 or SARS-CoV-2 N, with a fluorophore (FAM) labeled at the 5′ end, and a complementary strand (CSFV-Probe B or SARS-CoV-2-Probe B), combined with a quencher (BHQ2) labeled at the 3′ end.ResultsUsing linear molecular beacon probe technology, the detection limit of the RNA virus probe corresponding to CSFV and SARS-CoV-2 were as low as 0.28 nM and 0.24 nM, respectively. After CSFV E2 and SARS-CoV-2 N genes were transfected into corresponding host cells, the monitoring of RNA virus probes showed that fluorescence signals were dramatically enhanced in a concentration- and time-dependent manner. These results were supported by those of quantitative (qRT-PCR) and visualization (confocal microscopy) analyses. Furthermore, CSF-positive swine samples and simulated SARS-CoV-2 infected mouse samples were used to demonstrate their applicability for different distributions of viral nucleic acids in series tissues.ConclusionsThe proposed RNA virus probe could be used as a PCR-free, cost-effective, and rapid point-of-care (POC) diagnostic platform for target RNA virus detection, holding great potential for the convenient monitoring of different RNA viruses for early mass virus screening.Graphical

Performance of the TaqMan COVID-19 Pooling Kit for detection of SARS-CoV-2 in asymptomatic and symptomatic populations.

Clinical evidence for asymptomatic cases of coronavirus disease (COVID-19) has reinforced the significance of effective surveillance testing programs. Quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) assays are considered the ‘gold standard’ for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA. However, the labor and resource requirements can be prohibitive with respect to large testing volumes associated with the pandemic. Pooled testing algorithms may serve to increase testing capacity with more efficient resource utilization. Due to the lack of carefully curated cohorts, there is limited evidence for the applicability of RT-PCR pooling in asymptomatic COVID-19 cases. In this study, we compared the analytical sensitivity of the TaqMan™ SARS-CoV-2 Pooling Assay to detect one positive sample in a pool of five anterior nares swabs in symptomatic and asymptomatic cohorts at an institute of higher education. Positive pools were deconvoluted and each individual sample was retested using the TaqPath™ COVID-19 Combo Kit. Both assays target the open reading frame (ORF) 1ab, nucleocapsid (N), and spike (S) gene of the strain that originated in Wuhan, Hubei, China. Qualitative results demonstrated absolute agreement between pooled and deconvoluted samples in both cohorts. Independent t-test performed on Ct shifts supported an insignificant difference between cohorts with p-values of 0.306 (Orf1ab), 0.147 (N), and 0.052 (S). All negative pools were correctly reported as negative. Pooled PCR testing up to five samples is a valid method for surveillance testing of students and staff in a university setting, especially when the prevalence is expected to be low.

CoviXNet: A novel and efficient deep learning model for detection of COVID-19 using chest X-Ray images

The Coronavirus (COVID-19) pandemic has created havoc on humanity by causing millions of deaths and adverse physical and mental health effects. To prepare humankind for the fast and efficient detection of the virus and its variants shortly, COVID-19 detection using Artificial Intelligence and Computer-Aided Diagnosis has been the subject of several studies. To detect COVID-19, there are numerous publicly accessible datasets of Chest X-rays that the researchers have combined to solve the problem of inadequate data. The cause for concern here is that in combining two or more datasets, some of the images might be duplicates, so a curated dataset has been used in this study, taken from an author’s paper. This dataset consists of 1281 COVID-19, 3270 Normal X-rays, and 1656 viral-pneumonia infected Chest X-ray images. Dataset has been pre-processed and divided carefully to ensure that there are no duplicate images. A comparative study on many traditional pre-trained models was performed, analyzing top-performing models. Fine-tuned InceptionV3, Modified EfficientNet B0&B1 produced an accuracy of 99.78% on binary classification, i.e., covid-19 infected and normal Chest X-ray image. ResNetV2 had a classification accuracy of 97.90% for 3-class classification i.e., covid-19 infected, normal, and pneumonia. Furthermore, a trailblazing custom CNN-based model, CoviXNet, has been proposed consisting of 15 layers that take efficiency into account. The proposed model CoviXNet exhibited a 10-fold accuracy of 99.47% on binary classification and 96.61% on 3-class. CoviXNet has shown phenomenal performance with exceptional accuracy and minimum computational cost. We anticipate that this comparative study, along with the proposed model CoviXNet, can assist medical centers with the efficient real-life detection of Coronavirus.

Electromagnetically-driven integrated microfluidic platform using reverse transcription loop-mediated isothermal amplification for detection of severe acute respiratory syndrome coronavirus 2

Rapid, sensitive and accurate diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is of great need for effective quarantining and treatment. Real-time reverse-transcription polymerase chain reaction requiring thermocyling has been commonly used for diagnosis of SARS-CoV-2 though it may take two to 4 h before lengthy sample pretreatment process and require bulky apparatus and well-trained personnel. Since multiple reverse transcription loop-mediated isothermal amplification (multiple RT-LAMP) process without thermocycling is sensitive, specific and fast, an electromagnetically-driven microfluidic chip (EMC) was developed herein to lyse SARS-CoV-2 viruses, extract their RNAs, and perform qualitative analysis of three marker genes by on-chip multiple RT-LAMP in an automatic format within 82 min at a limit of detection of only ∼5000 copies per reaction (i.e. 200 virus/ μL). This compact EMC may be especially promising for SARS-CoV-2 diagnostics in resource-limited countries.

A Rapid, Whole Genome Sequencing Assay for Detection and Characterization of Novel Coronavirus (SARS-CoV-2) Clinical Specimens Using Nanopore Sequencing.

A new human coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged at the end of 2019 in Wuhan, China that caused a range of disease severities; including fever, shortness of breath, and coughing. This disease, now known as coronavirus disease 2019 (COVID-19), quickly spread throughout the world, and was declared a pandemic by the World Health Organization in March of 2020. As the disease continues to spread, providing rapid characterization has proven crucial to better inform the design and execution of control measures, such as decontamination methods, diagnostic tests, antiviral drugs, and prophylactic vaccines for long-term control. Our work at the United States Army’s Combat Capabilities Development Command Chemical Biological Center (DEVCOM CBC) is focused on engineering workflows to efficiently identify, characterize, and evaluate the threat level of any potential biological threat in the field and more remote, lower resource settings, such as forward operating bases. While we have successfully established untargeted sequencing approaches for detection of pathogens for rapid identification, our current work entails a more in-depth sequencing analysis for use in evolutionary monitoring. We are developing and validating a SARS-CoV-2 nanopore sequencing assay, based on the ARTIC protocol. The standard ARTIC, Illumina, and nanopore sequencing protocols for SARS-CoV-2 are elaborate and time consuming. The new protocol integrates Oxford Nanopore Technology’s Rapid Sequencing Kit following targeted RT-PCR of RNA extracted from human clinical specimens. This approach decreases sample manipulations and preparation times. Our current bioinformatics pipeline utilizes Centrifuge as the classifier for quick identification of SARS-CoV-2 and RAMPART software for verification and mapping of reads to the full SARS-CoV-2 genome. ARTIC rapid sequencing results, of previous RT-PCR confirmed patient samples, showed that the modified protocol produces high quality data, with up to 98.9% genome coverage at >1,000x depth for samples with presumably higher viral loads. Furthermore, whole genome assembly and subsequent mutational analysis of six of these sequences identified existing and unique mutations to this cluster, including three in the Spike protein: V308L, P521R, and D614G. This work suggests that an accessible, portable, and relatively fast sample-to-sequence process to characterize viral outbreaks is feasible and effective.

Therapeutic significance of nano- and biosensor technology in combating SARS-CoV-2: a review.

The diagnosis of novel coronavirus (COVID-19) has gained the spotlight of the world’s scientific community since December 2019 and it remains an important issue due to the emergence of novel variants around the globe. Early diagnosis of coronavirus is captious to prevent and hard to control. This pandemic can be eradicated by implementing suppressing strategies which can lead to better outcomes and more lives being saved. Therefore, the analysis showed that COVID-19 can only be managed by adopting public health measures, such as testing, isolation and social distancing. Much work has been done to diagnose coronavirus. Various testing technologies have been developed, opted and modified for rapid and accurate detection. The advanced molecular diagnosis relies on the detection of SARS-CoV-2 as it has been considered the main causative agent of this pandemic. Studies have shown that several molecular tests are considered essential for the confirmation of coronavirus infection. Various serology-based tests are also used in the detection and diagnosis of coronavirus including point-of-care assays and high-throughput enzyme immunoassays that aid in the diagnosis of COVID-19. Both these assays are time-consuming and have less diagnostic accuracy. Nanotechnology has the potential to develop new strategies to combat COVID-19 by developing diagnostics and therapeutics. In this review, we have focused on the nanotechnology-based detection techniques including nanoparticles and biosensors to obstruct the spread of SARS-CoV-2.

Rapid and Sensitive Detection of Antigen from SARS-CoV-2 Variants of Concern by a Multivalent Minibinder-Functionalized Nanomechanical Sensor.

New platforms for the rapid and sensitive detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern are urgently needed. Here we report the development of a nanomechanical sensor based on the deflection of a microcantilever capable of detecting the SARS-CoV-2 spike (S) glycoprotein antigen using computationally designed multivalent minibinders immobilized on a microcantilever surface. The sensor exhibits rapid (<5 min) detection of the target antigens down to concentrations of 0.05 ng/mL (362 fM) and is more than an order of magnitude more sensitive than an antibody-based cantilever sensor. Validation of the sensor with clinical samples from 33 patients, including 9 patients infected with the Omicron (BA.1) variant observed detection of antigen from nasopharyngeal swabs with cycle threshold (Ct) values as high as 39, suggesting a limit of detection similar to that of the quantitative reverse transcription polymerase chain reaction (RT-qPCR). Our findings demonstrate the use of minibinders and nanomechanical sensors for the rapid and sensitive detection of SARS-CoV-2 and potentially other disease markers.

Changes in Inpatient and Day Patient Treatment during the COVID-19 Pandemic: Insights and Outlook Results of a Study in an Adult Psychiatry Clinic in Germany

IntroductionPossible effects of pandemic-related restrictions and adjustments in psychiatric treatment are currently the focus of interest. This article addresses developments in this respect in our clinic.ObjectivesChanges in clinical practice that occurred during the COVID-19 pandemic are to be analysed with regard to possible risks for affected patients.MethodsA clinic-internal analysis was carried out, focusing on comparing a period during the COVID-19 pandemic (01.11.2020-30.04.2021) and a pre-pandemic reference period (01.11.2018-30.04.2019).ResultsFollowing trends were observed during the pandemic period: a. Day patient treatment: - The treatment volume fell to 44%. Notable reductions in the number of treatment cases with main diagnoses [ICD-10] F10.- and F30-F39 by &gt;65% were measured. b. Inpatient treatment: - no significant changes regarding socio-demographic patient data and concerning the type of admission and discharge, - detection of coronavirus SARS-CoV-2 by PCR test in 4.7% of the cases, - a decline in the treatment volume to 87% due to 8% decrease in the number of cases and 5% decrease in the ALOS, with patients with the main diagnosis [ICD-10] F10.- were most affected, - increases regarding the percentage of cases with the main diagnosis [ICD-10] F40-F48 (p&lt;0.05) and in the ALOS of this patient group (by 31%), - a significant rise (p&lt; 0.01) in the ratio of restrained treatment cases.ConclusionsRelated to the decrease in treatment volume, the increase in psychiatric intensive treatment and possible risks in terms of the care situation for patients with the main diagnoses [ICD-10] F10.-, F30-F39 and F40-F48 should be discussed in particular.DisclosureNo significant relationships.

COVID-19 neutralizing antibodies persist rate after vaccination in correlation with vaccine type in some Nasiriyah vaccinated citizen

Aim: The presence of neutralizing antibodies (NAbs) is an indicator of protective immunity for most viral infections. This study investigated the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibodies NAbs (IgM &amp; IgG) following vaccination with three common potential vaccines (Pfizer, AstraZeneca and Sino pharm), in Nasiriya city / south of Iraq. Methods. From September 2021 to April 2022. 158 participants who had completed COVID-19 vaccination (50 persons for each) were recruited and tested using Covid-19 neutralizing antibody kits, for NAbs evaluation. Results. Majority of the participants were 21–40 years old of age. NAbs were observed in 100% of enrolled individuals (vaccinated or not) but with significant difference in the IgM and IgG titers in correlate to the vaccine type, but there weren’t with other demographic factors effect. Nine days after second vaccine dose, spike protein neutralizing antibody levels were two-fold higher of IgM and 5-fold higher of IgG, exceeding titers of non-vaccinated SARS-CoV-2-naive control. Pfizer vaccine type against COVID-19 gave the highest IgM and IgG titers during the 6 months’ trial, with the lowest declining rate.

Evaluation of simple biosensors for efficient detection of coronavirus: A comprehensive review for the development of real-time monitoring systems

The origin of the virus known as coronavirus is unknown; the fact that this is the case lends credence to the opinion of the World Health Organization (WHO), which states that humans were most likely responsible for its genesis. At this very moment, the whole universe is confronted with a problem in the form of a catastrophic health crisis brought on by a widespread outbreak of the coronavirus. Even though it has been under control for a substantial length of time, this outbreak has not yet been brought under control or generated positive outcomes. Despite this, there has been no indication that it will. This is in spite of the fact that significant efforts have been invested in testing for COVID-19 contamination, isolating infected individuals, and isolating people who have been in touch with those infected cases. The Review of Simple Biosensors for Rapid Detection of Coronavirus recognized the evaluation of current proposals uncovered by researchers and bioengineers from all over the world about methods to control a coronavirus pandemic by rapid testing, in particular the review of simple biosensors. These researchers and bioengineers found current proposals about methods to control a coronavirus pandemic by rapid testing. These researchers and bioengineers uncovered the examination of the most recent suggestions. In recent years, the primary focus of biosensors as effective analytical equipment has been on full samples, with the ability to mark specimens. This shift in emphasis came about because of a shift in terminology. This has been shown to be the case in human as well as animal samples. In light of this, we have decided to do a comprehensive assessment of recently established biosensing technologies. Our main goal in doing this is to make it easier to spot coronavirus pandemics, which is why we are doing it.

Fluorescence spectrophotometry for COVID-19 determination in clinical swab samples.

Considering the limitations of the assays currently available for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its emerging variants, a simple and rapid method using fluorescence spectrophotometry was developed to detect coronavirus disease 2019 (COVID-19). Forty clinical swab samples were collected from the nasopharyngeal and oropharyngeal cavities of COVID-19-positive and -negative. Each sample was divided into two parts. The first part of the samples was analyzed using reverse transcription-polymerase chain reaction (RT-qPCR) as the control method to identify COVID-19-positive and -negative samples. The second part of the samples was analyzed using fluorescence spectrophotometry. Fluorescence measurements were performed at excitation and emission wavelengths ranging from 200 to 800 nm. Twenty COVID-19-positive samples and twenty COVID-19-negative samples were detected based on RT-qPCR results. The fluorescence spectrum data indicated that the COVID-19-positive and -negative samples had significantly different characteristics. All positive samples could be distinguished from negative samples by fluorescence spectrophotometry. Principal component analysis showed that COVID-19-positive samples were clustered separately from COVID-19-negative samples. The specificity and accuracy of this experiment reached 100%. Limit of detection (LOD) obtained 42.20 copies/ml (Ct value of 33.65 cycles) for E gene and 63.60 copies/ml (Ct value of 31.36 cycles) for ORF1ab gene. This identification process only required 4 min. Thus, this technique offers an efficient and accurate method to identify an individual with active SARS-CoV-2 infection and can be easily adapted for the early investigation of COVID-19, in general.

Evaluation of simple biosensors for efficient detection of coronavirus: A comprehensive review for the development of real-time monitoring systems

Evaluation of simple biosensors for efficient detection of coronavirus: A comprehensive review for the development of real-time monitoring systems

Automated, portable, and high-throughput fluorescence analyzer (APHF-analyzer) and lateral flow strip based on CRISPR/Cas13a for sensitive and visual detection of SARS-CoV-2

COVID-19 has erupted and quickly swept across the globe, causing huge losses to human health and wealth. It is of great value to develop a quick, accurate, visual, and high-throughput detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we developed a biosensor based on CRISPR/Cas13a combined with recombinase polymerase amplification (RPA) to detect S and Orf1ab genes of SARS-CoV-2 within 30 min. Most important of all, we developed an automated, portable, and high-throughput fluorescence analyzer (APHF-analyzer) with a 3D-printed microfluidic chip for sensitively detecting SARS-CoV-2, which addressed aerosol contamination issue and provided a more accurate and high-throughput detection during the on-site detection process. The detection limits of S gene and Orf1ab gene were as low as 0.68 fM and 4.16 fM. Furthermore, we used the lateral flow strip to realize visualization and point of care testing (POCT) of SARS-CoV-2. Therefore, profit from the efficient amplification of RPA and the high specificity of CRISPR/Cas13a, APHF-analyzer and the lateral flow strip to simultaneous detection of S gene and Orf1ab gene would be applied as a promising tool in the field of SARS-CoV-2 detection.

Conductive Silver/Carbon Fiber Films for Rapid Detection of Human Coronavirus.

Polymerase chain reaction has gained attention since the outbreak of novel coronavirus in 2019. Due to its high specificity and capability for early detection, it is considered a standard method for the diagnosis of infectious diseases. However, the conventional thermocyclers used for nucleic acid amplification are not suitable for point-of-care testing applications, as they require expensive instruments, high-power consumption, and a long turnaround time. To suppress the widespread of the pandemic, there is an urgent need for the development of a rapid, inexpensive, and portable thermal cycler. Therefore, in this paper, we present a conductive silver/carbon fiber film-based thermal cycler with low power consumption (<5 W), efficient heating (~4.5 °C/s), low cost (<USD 200), and handheld size (11.5 × 7.1 × 7.5 mm). The conductive film, which was used as a heating source of the thermal cycler, was fabricated by the electrochemical deposition method. The successful coating of Ag was characterized by a scanning electron microscope and confirmed by energy-dispersive X-ray spectroscopy. The film showed excellent electrical/thermal conductivity and durability. Using our thermal cycler, 35 cycles of amplification were accomplished within 10 min. We also successfully demonstrated the multiplexed detection of various human coronaviruses (e.g., OC43, 229E, and NL63) using our thermal cycler.

Isothermal amplification using sequence-specific fluorescence detection of SARS coronavirus 2 and variants in nasal swabs.

Coronavirus disease 2019 is a public health challenge requiring rapid testing for the detection of infections and transmission. Nucleic acid amplification tests targeting SARS coronavirus 2 (CoV2) are used to detect CoV2 in clinical samples. Real-time reverse transcription quantitative PCR is the standard nucleic acid amplification test for CoV2, although reverse transcription loop-mediated isothermal amplification is used in diagnostics. The authors demonstrate a sequence-specific reverse transcription loop-mediated isothermal amplification-based nucleic acid amplification assay that is finished within 30 min using minimally processed clinical nasal swab samples and describe a fluorescence-quenched reverse transcription loop-mediated isothermal amplification assay using labeled primers and a quencher oligonucleotide. This assay can achieve rapid (30 min) and sensitive (1000 plaque-forming units/ml) fluorescence detection of CoV2 (WA1/2020), B.1.1.7 (Alpha) and variants of concern Delta (B.1.617.2) and Omicron (B.1.1.529) in nasal samples.

Sensitively detecting antigen of SARS-CoV-2 by NIR-II fluorescent nanoparticles.

Early detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is an efficient way to prevent the spread of coronavirus disease 2019 (COVID-19). Detecting SARS-CoV-2 antigen can be rapid and convenient, but it is still challenging to develop highly sensitive methods for effective diagnosis. Herein, a lateral flow assay (LFA) based on fluorescent nanoparticles emitting in the second near-infrared (NIR-II) window is developed for sensitive detection of SARS-CoV-2 antigen. Benefiting from the NIR-II fluorescence with high penetration and low autofluorescence, such NIR-II based LFA allows enhanced signal-to-background ratio, and the limit of detection is down to 0.01 ng·mL−1 of SARS-CoV-2 antigen. In the clinical swab sample tests, the NIR-II LFA outperforms the colloidal gold LFA with higher overall percent agreement with the polymerase chain reaction test. The clinical samples with low antigen concentrations (∼ 0.015−∼ 0.068 ng·mL−1) can be successfully detected by the NIR-II LFA, but fail for the colloidal gold LFA. The NIR-II LFA can provide a promising platform for highly sensitive, rapid, and cost-effective method for early diagnosis and mass screening of SARS-CoV-2 infection.Electronic Supplementary MaterialSupplementary material (the operation procedure and cost of the materials needed of NIR-II lateral flow assays, the dynamic light scattering spectrum of the NIR-II nanoparticles, the components and testing principle, optimization of main parameters pertaining to the LFA performance, the colloidal gold LFA strip, the fluorescence intensity distribution curves and the T/C values of the strips for clinical samples by NIR-II LFA, and results of clinical swab samples detected by colloidal gold LFA) is available in the online version of this article at 10.1007/s12274-022-4351-1.

Highly Sensitive Electrochemical Immunosensor Platforms for Dual Detection of SARS-CoV-2 Antigen and Antibody based on Gold Nanoparticle Functionalized Graphene Oxide Nanocomposites.

In this work, we report a facile synthesis of graphene oxide–gold (GO–Au) nanocomposites by electrodeposition. The fabricated electrochemical immunosensors are utilized for the dual detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen and SARS-CoV-2 antibody. The GO–Au nanocomposites has been characterized by UV–vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) for its biosensing properties. The linear detection range of the SARS-CoV-2 antigen immunosensor is 10.0 ag mL–1 to 50.0 ng mL–1, whereas that for the antibody immunosensor ranges from 1.0 fg mL–1 to 1.0 ng mL–1. The calculated limit of detection (LOD) of the SARS-CoV-2 antigen immunosensor is 3.99 ag mL–1, and that for SARS-CoV-2 antibody immunosensor is 1.0 fg mL–1 with high sensitivity. The validation of the immunosensor has also been carried out on patient serum and patient swab samples from COVID-19 patients. The results suggest successful utilization of the immunosensors with a very low detection limit enabling its use in clinical samples. Further work is needed for the standardization of the results and translation in screen-printed electrodes for use in portable commercial applications.

Detection of SARS-CoV-2 Nucleocapsid, Spike, and Neutralizing Antibodies in Vaccinated Japanese.

Serological detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N), spike (S), and neutralizing antibodies (Abs) is commonly undertaken to evaluate the efficacy of vaccination. However, the relative efficiency of different SARS-CoV-2 Ab detection systems has not been extensively investigated. Here, we evaluated serological test systems in vaccinated Japanese. SARS-CoV-2 N, S, and neutralizing Abs in sera of 375 healthy subjects a mean 253 days after vaccination were assessed. The sensitivity of Elecsys Anti-SARS-CoV-2 S (Roche S) and Anti-SARS-CoV-2 S IgG (Fujirebio S) was 100% and 98.9%, respectively, with a specificity of 100% for both. The sensitivity of Anti-SARS-CoV-2 neutralizing Ab (MBL Neu) was 2.7%, and the specificity was 100%. Fujirebio S correlated with Roche S (rho = 0.9182, p = 3.97 × 10−152). Fujirebio S (rho = 0.1295, p = 0.0121) and Roche S (rho = 0.1232, p = 0.0170) correlated weakly with MBL Neu. However, Roche S did correlate with MBL Neu in patients with COVID-19 (rho = 0.8299, p = 1.01 × 10−12) and in healthy subjects more recently after vaccination (mean of 90 days, rho = 0.5306, p = 0.0003). Thus, the Fujirebio S and Roche S results were very similar, but neither correlated with neutralizing antibody titers by MBL Neu at a later time after vaccination.