scholarly journals A SARS-CoV-2 antigen rapid diagnostic test for resource limited settings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Erica Frew ◽  
Douglas Roberts ◽  
Shelly Barry ◽  
Matthew Holden ◽  
Amanda Restell Mand ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Management Strategies ◽  
Test Methods ◽  
Swab Sample ◽  
Primary Method ◽  
Antigen Test ◽  
Active Infection ◽  
Global Challenge ◽  
Open World ◽  
Resource Limited

AbstractSevere Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the causative agent of COVID-19 disease. RT-qPCR has been the primary method of diagnosis; however, the required infrastructure is lacking in many developing countries and the virus has remained a global challenge. More inexpensive and immediate test methods are required to facilitate local, regional, and national management strategies to re-open world economies. Here we have developed a SARS-CoV-2 antigen test in an inexpensive lateral flow format to generate a chromatographic result identifying the presence of the SARS-CoV-2 antigen, and thus an active infection, within a patient anterior nares swab sample. Our 15-min test requires no equipment or laboratory infrastructure to administer with a limit of detection of 2.0 × 102 TCID50/mL and 87.5% sensitivity, 100% specificity when tested against 40 known positive and 40 known negative patient samples established by a validated RT-qPCR test.

scholarly journals A SARS-CoV-2 Antigen Rapid Diagnostic Test for Resource Limited Settings

2021 ◽  
Author(s):  
Erica Frew ◽  
Douglas Roberts ◽  
Shelly Barry ◽  
Matthew Holden ◽  
Amanda Restell Mand ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Management Strategies ◽  
Test Methods ◽  
Swab Sample ◽  
Primary Method ◽  
Antigen Test ◽  
Active Infection ◽  
Global Challenge ◽  
Open World ◽  
Resource Limited

Abstract Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the causative agent of COVID-19 disease. RT-qPCR has been the primary method of diagnosis; however, the required infrastructure is lacking in many developing countries and the virus has remained a global challenge. More inexpensive and immediate test methods are required to facilitate local, regional, and national management strategies to re-open world economies. Here we have developed a SARS-CoV-2 antigen test in an inexpensive lateral flow format to generate a chromatographic result identifying the presence of the SARS-CoV-2 antigen, and thus an active infection, within a patient anterior nares swab sample. Our 15-minute test requires no equipment or laboratory infrastructure to administer with a limit of detection of 2.0 x 102 TCID50/mL and 87.5% sensitivity, 100% specificity when tested against 40 known positive and 40 known negative patient samples established by a validated RT-qPCR test.

scholarly journals Immunochromatographic Strip Test for Rapid Detection of Nevirapine in Plasma Samples from Human Immunodeficiency Virus-Infected Patients

2007 ◽  
Vol 51 (9) ◽  
pp. 3361-3363 ◽  
Author(s):  
Tim R. Cressey ◽  
Sawitree Nangola ◽  
Yardpiroon Tawon ◽  
Mookda Pattarawarapan ◽  
Marc Lallemant ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Limit Of Detection ◽  
Drug Level ◽  
Plasma Samples ◽  
Immunochromatographic Strip ◽  
Resource Limited ◽  
Qualitative Detection ◽  
Immunodeficiency Virus ◽  
Immunochromatographic Strip Test ◽  
Strip Test

ABSTRACT We report a novel one-step immunochromatographic strip test for the rapid, qualitative detection of nevirapine in plasma samples from human immunodeficiency virus-infected patients. The sensitivity was 100% (95% confidence interval [95% CI], 97.8 to 100%), and the specificity was 99.5% (95% CI, 97.2 to 99.9%). The limit of detection was 25 ng/ml. Immunochromatographic strip tests are simple, rapid, and cheap assays that could greatly facilitate drug level monitoring in resource-limited settings.

Laboratory Tests

2019 ◽  
pp. 13-106
Author(s):  
John G. Bartlett ◽  
Robert R. Redfield ◽  
Paul A. Pham
Keyword(s):  
False Negative ◽  
Test Methods ◽  
Screening Tests ◽  
Resistance Testing ◽  
Sexually Transmitted ◽  
Molecular Tests ◽  
Testing Strategies ◽  
Resource Limited ◽  
Confirmatory Tests ◽  
Home Tests

This chapter covers the following topics: HIV viruses including viral variants (group O and group N); immune responses to HIV and detection markers; HIV serologic tests; initial tests to detect HIV antibody; confirmatory tests to detect antibody, antigen, or RNA; false-negative and false-positive results; testing strategies and algorithms; alternative testing strategies for resource-limited countries; home tests; tests that use oral fluids; molecular tests to detect and monitor HIV infection; kinetics of viral nucleic acid production (including qualitative and quantitative RNA tests); HIV DNA assessment; uses of viral load tests; rapid molecular tests; resistance testing (including purpose and scope); resistance test methods; tests for sexually transmitted infections (STIs); screening tests for other infectious agents; and recommended reading.

scholarly journals Development and Evaluation of an iiPCR Assay for Salmonella and Shigella Detection on a Field-Deployable PCR System

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Tian Du ◽  
Ji-hong Lin ◽  
Jun-hua Zhao ◽  
Hai-bo Wang ◽  
Qiu-hua Mo
Keyword(s):  
Predictive Value ◽  
Large Scale ◽  
Limit Of Detection ◽  
Analytical Sensitivity ◽  
Pcr Assay ◽  
Preliminary Screening ◽  
Oral Transmission ◽  
Resource Limited ◽  
Clinical Accuracy ◽  
Insulated Isothermal Pcr

Background. Salmonella and Shigella are often associated with fecal-oral transmission and cause large-scale outbreaks in centralized catering units and, therefore, should be frequently and strictly monitored, especially among food handlers. However, no specific and sensitive on-site detection method is available until now. Methods. In this study, an insulated isothermal PCR assay for the detection of Salmonella and Shigella on a field-deployable PCR system was developed. Specificity, sensitivity, reproducibility, and clinical accuracy of the assay were characterized and evaluated. Results. The insulated isothermal PCR assay could be completed within 58 minutes with minimal pretreatment needed. The assay was specific and with good reproducibility. The limit of detection was 103 CFU/mL and 101 CFU/mL for Salmonella and Shigella, respectively, which was comparable to multiplex real-time PCR. Mock on-site clinical evaluation results showed that the analytical sensitivity and specificity of the insulated isothermal PCR assay were 100% and 96.6%, while the positive predictive value and negative predictive value were 94.1% and 100%, respectively. Conclusion. Based on our results, we believe that the assay developed herein could serve as an alternative method for preliminary screening and provide a valuable platform for the on-site detection of Salmonella and Shigella, especially in resource-limited and developing countries.

scholarly journals Proposal of De Novo Antigen Test for COVID-19: Ultrasensitive Detection of Spike Proteins of SARS-CoV-2

Diagnostics ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 594 ◽  
Author(s):  
Yuta Kyosei ◽  
Mayuri Namba ◽  
Sou Yamura ◽  
Rikiya Takeuchi ◽  
Noriko Aoki ◽  
...  
Keyword(s):  
De Novo ◽  
Limit Of Detection ◽  
False Negative ◽  
Cost Effective ◽  
Detection Sensitivity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antigen Test ◽  
Virus Rna ◽  
Antigen Tests ◽  
Spike Proteins

Polymerase chain reaction (PCR)-based antigen tests are technically difficult, time-consuming, and expensive, and may produce false negative results requiring follow-up confirmation with computed tomography. The global coronavirus disease 2019 (COVID-19) pandemic has increased the demand for accurate, easy-to-use, rapid, and cost-effective antigen tests for clinical application. We propose a de novo antigen test for diagnosing COVID-19 using the combination of sandwich enzyme-linked immunosorbent assay and thio-nicotinamide adenine dinucleotide (thio-NAD) cycling. Our test takes advantage of the spike proteins specific to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. The limit of detection of our test was 2.3 × 10−18 moles/assay. If the virus has ~25 spike proteins on its surface, our method should detect on the order of 10−20 moles of virus/assay, corresponding to ~104 copies of the virus RNA/assay. The detection sensitivity approaches that of PCR-based assays because the average virus RNA load used for PCR-based assays is ~105 copies per oro- or naso-pharyngeal swab specimen. To our knowledge, this is the first ultrasensitive antigen test for SARS-CoV-2 spike proteins that can be performed with an easy-to-use microplate reader. Sufficient sensitivity can be achieved within 10 min of thio-NAD cycling. Our antigen test allows for rapid, cost-effective, specific, ultrasensitive, and simultaneous multiple measurements of SARS-CoV-2, and has broad application for the diagnosis for COVID-19.

MicroVal: A European Approach to the Certification of New Microbiological Methods

1998 ◽  
Vol 61 (11) ◽  
pp. 1579-1582 ◽  
Author(s):  
ROY P. BETTS ◽  
IRENE M. F. RENTENAAR
Keyword(s):  
Method Validation ◽  
Limit Of Detection ◽  
Collaborative Study ◽  
Reference Method ◽  
Test Methods ◽  
International Standards ◽  
Test Method ◽  
Eu Member States ◽  
New Methods ◽  
Microbiological Methods

In recent years, food microbiologists have seen the development of a range of nonstandard methods designed to enumerate or determine the presence of various microorganisms in food products. Generally the new methods are designed to give the microbiologist advantages, such as greater automation or faster results, over standard conventional methods. The new methods, however, have often not been thoroughly tested to give the end user confidence in the results. In order to generate data to show that new methods give results that are comparable with standard methods, they must be validated. A number of validation schemes have been developed in various countries throughout the world. There has not, however, been an acceptable scheme recognized throughout Europe. The MicroVal project has been involved in the development of a European microbiological method validation and certification scheme; it involves 21 partners from 7 EU member States. New methods that are tested by the MicroVal system will undergo initial testing in a single expert laboratory, to establish the test's specificity, limit of detection, relative accuracy, sensitivity, and linearity. This testing will be followed by a collaborative study in a minimum of eight laboratories, which will be used to determine the test precision, repeatability, and reproducibility. All results will be assessed by two expert reviewers who will recommend or reject the test. Tests that are recommended will be finally accepted by a MicroVal committee. The committee will pass its comments to one of several certification bodies (working together through a memorandum of understanding) who will certify that the new method gives results that are equivalent to the reference method used throughout the validation work. The technical rules that describe the work required to certify a method are currently being considered by the European Committee for Standardization (CEN), with the objective that the rules will become a CEN standard for the certification of new test methods. When this objective has been achieved the rules will become an International Standards Organization (ISO) standard for new test method validation.

scholarly journals Amplified parallel antigen rapid test for point-of-care salivary detection of SARS-CoV-2 with improved sensitivity

2021 ◽  
Vol 189 (1) ◽  
Author(s):  
Danny Jian Hang Tng ◽  
Bryan Chu Yang Yin ◽  
Jing Cao ◽  
Kwan Ki Karrie Ko ◽  
Kenneth Choon Meng Goh ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Rapid Test ◽  
Spike Protein ◽  
Angiotensin Converting Enzyme 2 ◽  
Resource Limited ◽  
Order Of Magnitude ◽  
Rapid Tests ◽  
Point Of Care Tests ◽  
Control Study

AbstractIn the ongoing COVID-19 pandemic, simple, rapid, point-of-care tests not requiring trained personnel for primary care testing are essential. Saliva-based antigen rapid tests (ARTs) can fulfil this need, but these tests require overnight-fasted samples; without which independent studies have demonstrated sensitivities of only 11.7 to 23.1%. Herein, we report an Amplified Parallel ART (AP-ART) with sensitivity above 90%, even with non-fasted samples. The virus was captured multimodally, using both anti-spike protein antibodies and Angiotensin Converting Enzyme 2 (ACE2) protein. It also featured two parallel flow channels. The first contained spike protein binding gold nanoparticles which produced a visible red line upon encountering the virus. The second contained signal amplifying nanoparticles that complex with the former and amplify the signal without any linker. Compared to existing dual gold amplification techniques, a limit of detection of one order of magnitude lower was achieved (0.0064 ng·mL–1). AP-ART performance in detecting SARS-CoV-2 in saliva of COVID-19 patients was investigated using a case–control study (139 participants enrolled and 162 saliva samples tested). Unlike commercially available ARTs, the sensitivity of AP-ART was maintained even when non-fasting saliva was used. Compared to the gold standard reverse transcription-polymerase chain reaction testing on nasopharyngeal samples, non-fasting saliva tested on AP-ART showed a sensitivity of 97.0% (95% CI: 84.7–99.8); without amplification, the sensitivity was 72.7% (95% CI: 83.7–94.8). Thus, AP-ART has the potential to be developed for point-of-care testing, which may be particularly important in resource-limited settings, and for early diagnosis to initiate newly approved therapies to reduce COVID-19 severity. Graphical abstract

scholarly journals Clinico-epidemiological profile of COVID-19 among health care workers from a tertiary care hospital

2021 ◽  
Author(s):  
Anuradha Tolpadi ◽  
Abhijeet Mane ◽  
Jitendra Oswal ◽  
Sujata Rege ◽  
Meera Modak ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Tertiary Care ◽  
Management Strategies ◽  
Care Hospital ◽  
Antigen Test ◽  
Rt Pcr ◽  
Tertiary Care Centre ◽  
Care Workers ◽  
Global Health Issue ◽  
Epidemiological Profile

Background: Coronavirus disease 2019 (COVID-19) is a global health issue. Healthcare workers (HCWs) are especially vulnerable to infection by SARS-CoV-2. The present study was conducted to determine the proportion of HCWs infected with COVID 19 in a tertiary care centre with emphasis on the epidemiological and clinical aspectMethods: HCWs (symptomatic and asymptomatic contacts) who tested positive for COVID-19 by SARS-CoV-RTPCR or COVID-19 rapid antigen test were included in the study. Demographic and clinical data of the infected HCWs was obtained through a detailed telephonic interview with structured questionnaire.Results: Out of total 921 HCWs tested for COVID-19 (SARS-CoV-2 RT-PCR and Rapid antigen test), 323 (35%) HCWs were positive. Proportion of COVID-19 positive HCWs among all HCWs was 13.67% (323/2362). Most COVID-19 positive HCWs (88%) were symptomatic. Majority of infected HCWs (62.23%) were between the age group of 21-30 years. Nurses were the most predominantly affected among various categories of HCWs (42.41%). Fever was the most common presenting symptom, seen in 160 (49.50%) HCWs. Comorbidities were found in 28 (8.66%) of infected HCWs. Majority of HCWs (86%) suffered from mild infection.Conclusions: HCWs, especially nurses, face a high risk of COVID-19 infection while providing care for suspected or confirmed COVID-19 patients. It is important to characterize the epidemiological and clinical profile of HCWs regarding COVID-19 for formulation of prevention and management strategies.

scholarly journals Analytical and Clinical Validation for RT-qPCR detection of SARS-CoV-2 without RNA extraction

2020 ◽  
Author(s):  
José P. Miranda ◽  
Javiera Osorio ◽  
Mauricio Videla ◽  
Gladys Angel ◽  
Rossana Camponovo ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Rna Extraction ◽  
Clinical Decision ◽  
Laboratory Diagnosis ◽  
Standard Protocol ◽  
Safe Alternative ◽  
Widespread Application ◽  
Decision Limit ◽  
Resource Limited ◽  
Historical Samples

AbstractBackgroundThe recent COVID-19 pandemic has posed an unprecedented challenge to laboratory diagnosis, based on the amplification of SARS-CoV-2 RNA. With global contagion figures exceeding 4 million persons, the shortage of reagents for RNA extraction represents a bottleneck for testing globally. We present the validation results for a RT-qPCR protocol without prior RNA extraction. Because of its simplicity, this protocol is suitable for widespread application in resource-limited settings.MethodsOptimal protocol was selected by comparing RT-qPCR performance under a set of thermal (65°, 70°, and 95° for 5, 10, and 30 minutes) and amplification conditions (3 or 3,5 uL loading volume; 2 commercial RT-qPCR kits with limit of detection below 10 copies/sample) in nasopharyngeal swabs stored at 4°C in sterile Weise’s buffer pH 7.2. The selected protocol was evaluated for classification concordance with the standard protocol (automated RNA extraction) in 130 routine samples and in 50 historical samples with Cq values near to the clinical decision limit.ResultsOptimal selected conditions were: Thermal shock at 70° C for 10 minutes, loading 3.5 ul in the RT-qPCR. Prospective evaluation in 130 routine samples showed 100% classification concordance with the standard protocol. The evaluation in historical samples, selected because their Cqs were at the clinical decision limit, showed 94% concordance with our confirmatory-gold standard which includes manual RNA extraction.ConclusionsThese results validate the use of this direct RT-qPCR protocol as a safe alternative for SARS CoV-2 diagnosis in case of a shortage of reagents for RNA extraction, with minimal clinical impact.

scholarly journals Detection of Borrelia burgdorferi antigens in tissues and plasma during early infection in a mouse model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Victoria Dolange ◽  
Stéphanie Simon ◽  
Nathalie Morel
Keyword(s):  
Mouse Model ◽  
Borrelia Burgdorferi ◽  
Lyme Borreliosis ◽  
Limit Of Detection ◽  
Mean Value ◽  
Indirect Detection ◽  
Post Inoculation ◽  
Active Infection ◽  
Serological Tests ◽  
Blood Marker

AbstractBorrelia burgdorferi is the causative agent of Lyme borreliosis, which is the most common tick-borne human disease in Europe and North America. Currently, the diagnosis of Lyme borreliosis is based on serological tests allowing indirect detection of anti-Borrelia antibodies produced by patients. Their main drawback is a lack of sensitivity in the early phase of disease and an incapacity to prove an active infection. Direct diagnostic tests are clearly needed. The objectives of this study were to produce tools allowing sensitive detection of potential circulating Borrelia antigens and to evaluate them in a mouse model. We focused on two potential early bacterial makers, the highly variable OspC protein and the conserved protein FlaB. High-affinity monoclonal antibodies were produced and used to establish various immunoassays and western blot detection. A very good limit of detection for OspC as low as 17 pg/mL of sample was achieved with SPIE-IA. In infected mice, we were able to measure OspC in plasma with a mean value of 10 ng/mL at 7 days post-inoculation. This result suggests that OspC could be a good blood marker for diagnosis of Lyme borreliosis and that the tools developed during this study could be very useful.

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