antigen detection
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Diagnostics ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 136
Author(s):  
Nitaya Indrawattana ◽  
Pisinee Aiumurai ◽  
Nawannaporn Sae-lim ◽  
Watee Seesuay ◽  
Onrapak Reamtong ◽  
...  

A point-of-care diagnostic for early and rapid diagnosis of scrub typhus caused by Orientia tsutsugamushi is required for prompt and proper treatment of patients presenting with undifferentiated febrile illnesses. In this study, an immunochromatographic antigen detection test kit (ICT AgTK) that targets the highly conserved O. tsutsugamushi 60 kDa GroEL chaperonin (heat shock protein 60) was developed. E. coli-derived recombinant GroEL expressed from DNA coding for the consensus sequence of 32 GroEL gene sequences extracted from the GenBank database was used to immunize rabbits and mice. Rabbit polyclonal antibodies (pAb) were used for preparing a gold-pAb conjugate, and the rGroEL-specific mouse monoclonal antibody was used as the antigen detection reagent at the ICT test line. In-house validation revealed that the ICT AgTK gave 85, 100 and 95% diagnostic sensitivity, specificity and accuracy, respectively, compared to the combined clinical features and standard IFA when tested on 40 frozen serum samples. The test kits correctly identified 10 scrub typhus samples out of 15 fresh plasma/buffy coat samples of patients with febrile illnesses. For independent laboratory validation, the ICT AgTK was sent to one provincial hospital. The ICT AgTK utilized by the hospital medical technologist correctly identified six scrub typhus samples out of 20 serum samples of patients with fever, as confirmed by specific IgM/IgG detection by IFA. The ICT AgTK is easy to perform with rapid turn-around time. It has the potential to be used as an important tool for on-site and early scrub typhus diagnosis by allowing testing of freshly collected samples (serum, plasma or buffy coat), especially in resource-limited healthcare settings.


Diagnostics ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 104
Author(s):  
Dorian Petonnet ◽  
Stéphane Marot ◽  
Isabelle Leroy ◽  
Julien Cohier ◽  
Charline Ramahefasolo ◽  
...  

SARS-CoV-2 viral antigen detection may be an interesting alternative to RT-PCR for the diagnosis of SARS-CoV-2 infection as a less laborious or expensive method but requires validation. This study aimed to compare the performance of the DiaSorin™ LiaisonXL automated quantitative antigen test (QAT) and the AAZ™ rapid antigen test (RAT) to the DiaSorin™ MDX RT-PCR assay. A total of 242 nasopharyngeal samples were tested at La Pitié-Salpêtrière University Hospital (Paris, France). Performances for the detection of variants of SARS-CoV-2 were further investigated. RATs were visually read for qualitative results and band intensity was determined. Overall sensitivity was 63.2% for QAT and 58.6% for RAT. For RT-PCR Ct value 25, sensitivity was 89.8% for both tests. Both tests showed comparable sensitivity for detection of variants. There was a strong relationship between antigen concentration and band positivity. On the same set of samples these tests share similar performances.


2022 ◽  
Author(s):  
Nareshkumar Poopalasingam ◽  
Michael Korenkov ◽  
Artem Ashurov ◽  
Janina Strobel ◽  
Irina Fish ◽  
...  
Keyword(s):  

2021 ◽  
Vol 14 (4) ◽  
pp. 2029-2039
Author(s):  
Thyazen Alhakimi ◽  
Toto Subroto ◽  
Muhammad Yusuf ◽  
Wyanda Arnafia ◽  
Ani Melani Maskoen ◽  
...  

SARS disease reappeared at the end of 2019 with a new name as Coronavirus Disease 2019 (COVID-19) caused by a new virus called SARS-CoV-2. This virus has spread throughout the world until recently and caused massive deaths and losses. The nucleic acid test in the form of real-time reverse transcriptase-polymerase chain reaction (RT-PCR) is very important to diagnose COVID-19 in patients, but this method has several drawbacks such as operators who have to be trained, the diagnosis results appear in a relatively long time, and the examination price relatively expensive. This research was conducted to produce immunoglobulin Y (IgY) extracted from chicken egg yolk targeting the S-protein receptor-binding domain (RBD) on SARS-CoV-2 as a component of the surface plasmon resonance (SPR) SARS-CoV-2 antigen detection kit. This research was started by extracting IgY from hyperimmune chicken egg yolks with the polyethylene glycol (PEG) precipitation method and continued with dialysis. The extracted IgY was further purified using thiophilic adsorption chromatography and concentrated by using Amicon® Ultra-15 ultrafiltration. The IgY activity against SARS-CoV-2 RBD was tested qualitatively using the agar gel precipitation test (AGPT) technique and the total protein content was determined using the Lowry method. IgY was tested for its affinity against SARS-CoV-2 RBD using SPR. The IgY concentration obtained was 11 mg/mL. The AGPT result showed the presence of IgY activity against SARS-CoV-2 RBD isolated from egg yolk and chicken serum after 8 weeks after the first vaccination of chickens. The SDS-PAGE results showed a very clear band of IgY characters. The obtained IgY showed adequate interaction with commercial SARS-CoV-2 RBD on an SPR device. The purified IgY was able to bind with protein-S RBD and showed a fairly good affinity for the SARS-CoV-2 antigen sample. The results of these observations indicate that IgY anti-S-protein SARS-CoV-2 can be produced and purified from chicken egg yolk and can be used as a diagnostic component to detect SARS-CoV-2 antigen, especially on SPR.


Biosensors ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 13
Author(s):  
Tao Peng ◽  
Xueshima Jiao ◽  
Zhanwei Liang ◽  
Hongwei Zhao ◽  
Yang Zhao ◽  
...  

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory coronavirus 2 (SARS-CoV-2) is still raging all over the world. Hence, the rapid and sensitive screening of the suspected population is in high demand. The nucleocapsid protein (NP) of SARS-CoV-2 has been selected as an ideal marker for viral antigen detection. This study describes a lateral flow immunoassay (LFIA) based on colloidal gold nanoparticles for rapid NP antigen detection, in which sensitivity was improved through copper deposition-induced signal amplification. The detection sensitivity of the developed LFIA for NP antigen detection (using certified reference materials) under the optimized parameters was 0.01 μg/mL and was promoted by three orders of magnitude to 10 pg/mL after copper deposition signal amplification. The LFIA coupled with the copper enhancement technique has many merits such as low cost, high efficiency, and high sensitivity. It provides an effective approach to the rapid screening, diagnosis, and monitoring of the suspected population in the COVID-19 outbreak.


2021 ◽  
Vol 13 (4) ◽  
pp. 66-71
Author(s):  
N. T. Mirzoev ◽  
S. N. Sidorchuk ◽  
Yu. I. Bulan’kov ◽  
K. V. Kas’janenko

Objective: assess the modern value of group А β-hemolytic streptococcus in patients with acute tonsillitis and the effectiveness of the rapid streptococcal antigen detection method.Materials and methods: microbial landscape assessment of acute tonsillitis was based on retrospective analysis of 902 bacterial culture results of a throat swab of patients with syndromes of acute tonsillitis treated in the Infectious Diseases Clinic of the Military Medical Academy named after S.M. Kirov during the period of 2019-2020. The effectiveness of the rapid streptococcal antigen detection method in the oropharynx was determined by a prospective study involving 35 patients with acute tonsillitis.Results: in the study, we have found that bacterial culture results of a throat swab, the following were more common: Nesseria species (39 %), Streptococcus viridans (23 %), and Staphylococcus aureus (17 %). The frequency of detection of β-hemolytic streptococcus was 1 %. The rapid diagnostic system «Streptatest» in patients with acute tonsillitis has demonstrated efficiency, under which that sensitivity of test was 80 %, specificity – 90 %, positive predictive value – 57,14 %, negative predictive value – 96,43 %.Conclusions: the frequency of group A β-hemolytic streptococcus in patients with lesion of lymphoid tissues of the oropharynx has declined significantly nowadays. The rapid diagnostic system «Streptatest» is a highly effective medical product that can be used in both hospital and pre-hospital stage. 


Chemosensors ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Chia-Ming Yang ◽  
Jia-Yuan Chang ◽  
Min-Yi Chen ◽  
Chao-Sung Lai

To evaluate point-of-care testing (POCT) for the potential early detection of biomarkers of Parkinson’s disease, a systematic investigation of portable and low-cost platforms is performed based on the Proton-enzyme-linked immunosorbent assay (Proton-ELISA) methodology. The detection of the α-synuclein antigen was first presented by biotin-relative linkers, and glucose substrate solution was first performed with a systematic experimental design to optimize the sensing results. All materials in this study are commercially available. Three different experiments with the partitional check were performed to investigate the Proton-ELISA platform, including proton catalyzed efficiency, blocking efficiency, and full Proton-ELISA procedure. The response time was selected as 15 min by the time-dependent curves of a full reaction. The limit of detection of conventional ELISA kits is 0.169 ng/mL, which is much lower than the Proton-ELISA results. The final response of the full Proton-ELISA procedure to pH changes was approximately 0.60 and 0.12 for α-synuclein antigen concentrations of 100 ng/mL and 4 ng/mL, respectively. With the partitional check, pH changes of pure glucose substrate and conjugated oxidase and interference of the nonspecific binding are 1.7 and 0.04, respectively. The lower pH changes far from the partitional check results can be concluded for the properties of glucose oxidase conjugation, including the isoelectric point and binding affinity modification by the testing environment. This preliminary guideline can be used as a lesson learnt to speed up following studies of the evaluation and optimization of other antigen detection. Therefore, Proton-ELISA can be suggested for some special applications with the help of custom-designed conjugation in the environment with less degradation or interference and a proper detection concentration range.


COVID ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 775-783
Author(s):  
Hoi-Ying Lam ◽  
Ka-Yi Leung ◽  
Ruiqi Zhang ◽  
Danlei Liu ◽  
Yujing Fan ◽  
...  

Antigen detection rapid diagnostic tests have been developed for first-line large-scale screening given their rapidity, simplicity, and accuracy. This study evaluates the diagnostic performance of an antigen detection rapid diagnostic test (BLOK BioScience, London, UK) detecting SARS-CoV-2 nucleocapsid protein. Serially diluted SARS-CoV-2 isolate and 110 NPS from COVID-19 patients were tested to determine the test’s sensitivity, and other viral isolates and 20 NPS from non-infected individuals were, for specificity, also tested. Ten clinical samples from COVID-19 patients with SARS-CoV-2 variants, including alpha, beta, gamma, delta, and eta variants, were collected to evaluate the test’s potential application in detecting emerging variants. Overall sensitivity was 92%, and stratifying into viral loads yielded 100% for Ct < 25 samples including SARS-CoV-2 variants, but 11.11% for Ct ≥ 30 samples. The analytical sensitivity of log10 TCID50/mL 2.0 was identified for SARS-CoV-2. Ninety-seven percent specificity with only SARS-CoV cross-reactivity lead to the Youden index of 0.89. The rapid diagnostic test has a high sensitivity for detecting SARS-CoV-2 in high viral load samples, possibly including emerging SARS-CoV-2 variants, but reduced sensitivity in low viral load samples suggests its optimized usage as a complementary testing method to other tests, including RT-PCR or a point-of-care test for large-scale screening, particularly for pandemic areas or airport border infection control.


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