Saliva-based point-of-care testing techniques for COVID-19 detection.
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ABSTRACT:
SUBMITTER: Wang S
PROVIDER: S-EPMC9056993 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:There has been a long-standing interest in point-of-care (POC) diagnostics as a tool to improve patient care because it can provide rapid, actionable results near the patient. Some of the successful examples of POC testing include lateral flow assays, urine dipsticks, and glucometers. Unfortunately, POC analysis is somewhat limited by the ability to manufacture simple devices to selectively measure disease specific biomarkers and the need for invasive biological sampling. Next generation POCs are being developed that make use of microfluidic devices to detect biomarkers in biological fluids in a non-invasive manner, addressing the above-mentioned limitations. Microfluidic devices are desirable because they can provide the ability to perform additional sample processing steps not available in existing commercial diagnostics. As a result, they can provide more sensitive and selective analysis. While most POC methods make use of blood or urine as a sample matrix, there has been a growing push to use saliva as a diagnostic medium. Saliva represents an ideal non-invasive biofluid for detecting biomarkers because it is readily available in large quantities and analyte levels reflect those in blood. However, using saliva in microfluidic devices for POC diagnostics is a relatively new and an emerging field. The overarching aim of this review is to provide an update on recent literature focused on the use of saliva as a biological sample matrix in microfluidic devices. We will first cover the characteristics of saliva as a sample medium and then review microfluidic devices that are developed for the analysis of salivary biomarkers.
| S-EPMC9925318 | biostudies-literature
Project description:Serological tests play an important role in the fight against Coronavirus Disease 2019 (COVID-19), including monitoring the dynamic immune response after vaccination, identifying past infection and determining community infection rate. Conventional methods for serological testing, such as enzyme-linked immunosorbent assays and chemiluminescence immunoassays, provide reliable and sensitive antibody detection but require sophisticated laboratory infrastructure and/or lengthy assay time. Conversely, lateral flow immunoassays are suitable for rapid point-of-care tests but have limited sensitivity. Here, we describe the development of a rapid and sensitive magnetofluidic immuno-PCR platform that can address the current gap in point-of-care serological testing for COVID-19. Our magnetofluidic immuno-PCR platform automates a magnetic bead-based, single-binding, and one-wash immuno-PCR assay in a palm-sized magnetofluidic device and delivers results in ∼30 min. In the device, a programmable magnetic arm attracts and transports magnetically-captured antibodies through assay reagents pre-loaded in a companion plastic cartridge, and a miniaturized thermocycler and a fluorescence detector perform immuno-PCR to detect the antibodies. We evaluated our magnetofluidic immuno-PCR with 108 clinical serum/plasma samples and achieved 93.8% (45/48) sensitivity and 98.3% (59/60) specificity, demonstrating its potential as a rapid and sensitive point-of-care serological test for COVID-19.
| S-EPMC8458161 | biostudies-literature
Project description:Salivary pepsin is a promising marker for the non-invasive diagnosis of laryngopharyngeal reflux (LPR). For reliable results regarding pepsin in saliva, it is critical to standardize the collection, storage, and pre-processing methods. In this study, we optimized the saliva collection protocols, including storage conditions, i.e., solution, temperature, and time, and the pre-processing filter for pepsin. Moreover, we prepared a simple immunochromatographic strip for the rapid detection of pepsin and evaluated its sensing performance. As a result, we selected a polypropylene (PP) filter as the pre-processing filter for salivary pepsin in low resource settings, such as those where point of care testing (POCT) is conducted. This filter showed a similar efficiency to the centrifuge (standard method). Finally, we detected the pepsin using gold nanoparticles conjugated with monoclonal pepsin antibody. Under optimized conditions, the lower limit of detection for pepsin test strips was determined as 0.01 ?g/mL. Furthermore, we successfully detected the salivary pepsin in real saliva samples of LPR patients, which were pre-processed by the PP filter. Therefore, we expect that our saliva collection protocol and pepsin immunochromatographic strip can be utilized as useful tools for a non-invasive diagnosis/screening of LPR in POCT.
| S-EPMC6982828 | biostudies-literature
Project description:The COVID-19 pandemic has posed enormous challenges for existing diagnostic tools to detect and monitor pathogens. Therefore, there is a need to develop point-of-care (POC) devices to perform fast, accurate, and accessible diagnostic methods to detect infections and monitor immune responses. Devices most amenable to miniaturization and suitable for POC applications are biosensors based on electrochemical detection. We have developed an impedimetric immunosensor based on an interdigitated microelectrode array (IMA) to detect and monitor SARS-CoV-2 antibodies in human serum. Conjugation chemistry was applied to functionalize and covalently immobilize the spike protein (S-protein) of SARS-CoV-2 on the surface of the IMA to serve as the recognition layer and specifically bind anti-spike antibodies. Antibodies bound to the S-proteins in the recognition layer result in an increase in capacitance and a consequent change in the impedance of the system. The impedimetric immunosensor is label-free and uses non-Faradaic impedance with low nonperturbing AC voltage for detection. The sensitivity of a capacitive immunosensor can be enhanced by simply tuning the ionic strength of the sample solution. The device exhibits an LOD of 0.4 BAU/ml, as determined from the standard curve using WHO IS for anti-SARS-CoV-2 immunoglobulins; this LOD is similar to the corresponding LODs reported for all validated and established commercial assays, which range from 0.41 to 4.81 BAU/ml. The proof-of-concept biosensor has been demonstrated to detect anti-spike antibodies in sera from patients infected with COVID-19 within 1 h. Photolithographically microfabricated interdigitated microelectrode array sensor chips & label-free impedimetric detection of COVID-19 antibody.
| S-EPMC9805445 | biostudies-literature
Project description:RNA-Seq was used to study changes in gene expression in saliva samples from 266 human subjects after SARS-COV-2 infection, vaccination, or combined infection and vaccination (breakthrough). Approximately equal numbers of males and females, matched for age, were profiled after subjects tested positive for COVID-19 by PCR and sequencing of the variant. In addition to samples from uninfected controls with and without vaccination, samples from infected subjects with and without vaccination that represent eight major SARS-COV-2 lineages are included: epsilon, iota, alpha, delta, omicron BA.1, omicron BA.2, omicron BA.4, and omicron BA.5. Stranded single-end sequencing was performed using standard Illumina protocols. Reads were quantified to hg38 human transcriptome using Salmon after adapter trimming. Quantified reads were filtered to remove features with fewer than one count in 80% of the samples, and normalized using TPM, followed by quantile and log2 transformation.
2023-09-19 | GSE212191 | GEO
Project description:The COVID-19 pandemic is growing rapidly, with over 37 million cases and more than 1 million deaths reported by mid-October, 2020, with true numbers likely to be much higher in the many countries with low testing rates. Many communities are highly vulnerable to the devastating effects of COVID-19 because of overcrowding in domestic settings, high burden of comorbidities, and scarce access to health care. Access to testing is crucial to globally recommended control strategies, but many communities do not have adequate access to timely laboratory services. Geographic dispersion of small populations across islands and other rural and remote settings presents a key barrier to testing access. In this Personal View, we describe a model for the implementation of decentralised COVID-19 point-of-care testing in remote locations by use of the GeneXpert platform, which has been successfully scaled up in remote Aboriginal and Torres Strait Islander communities across Australia. Implementation of the decentralised point-of-care testing model should be considered for communities in need, especially those that are undertested and socially vulnerable. The decentralised testing model should be part of the core global response towards suppressing COVID-19.
| S-EPMC7758179 | biostudies-literature
Project description:ObjectivesRisk of hospital-acquired COVID-19 (HA-COVID-19) infection is increased by cohorting infected and non-infected patients together in assessment areas, whist awaiting laboratory PCR results. Molecular point-of-care tests (mPOCT) reduce time to results and improve patient flow but the impact on HA-COVID-19 is unknown.MethodsIn this pre and post implementation study patients were evaluated across two time periods: March 1st to August 13th 2020, prior to the introduction of mPOCT in medical admissions areas, and 14th August 2020 to 1st April 2021, after mPOCT introduction. The primary outcome was proportion of HA-COVID-19 infection among all COVID-19 positive patients. Secondary outcome measures included time to SARS-CoV-2 results, length of time spent in the medical assessment area and comparison of local, regional and national proportions of HA-COVID-19.Results1988 patients were admitted through the acute medicine admission cohorting area and tested for SARS-CoV-2 prior to introducing mPOCT and 4640 afterwards. Median (IQR) time to SARS-CoV-2 result was 6.5 (2.1-17.9) hours prior to introducing mPOCT and 1.0 (0.8-1.3) hours afterwards (p < 0.0001). Median (IQR) duration in the assessment cohort area was 12.0 (4.8-20.6) hours prior to introduction of POCT and 3.2 (2.0-5.6) hours afterwards (p < 0.0001). The proportion of hospital-acquired COVID-19 cases was 108 (16.5%) of 654 prior to introducing mPOCT compared with 168 (9.4%) of 1782 afterwards, (HR 0.55, 95%CI 0.43-0.70; p < 0.0001). In the period following the introduction of mPOCT up to 1st April 2021 the median proportion of HA-COVID-19 was 13.6% (95%CI 8.2-18.9%) locally, compared with 43.8% (95%CI 37.8-49.9%) for all acute NHS trusts regionally and 30.9% (95%CI 28.4-33.5%) for all NHS trusts nationally.ConclusionsRoutine mPOCT for SARS-CoV-2 was associated with reduced time to results, time spent in admission cohort areas, and hospital-acquired COVID-19, compared to laboratory PCR.
| S-EPMC8802147 | biostudies-literature
Project description:ObjectivesThe Abbot ID NOW COVID-19 assay and Quidel Sofia 2 SARS Antigen FIA are point-of-care assays that offer rapid testing for severe acute respiratory syndrome coronavirus 2 viral RNA and nucleocapsid protein, respectively. Given the utility of these devices in the field, we investigated the feasibility and safety of using the ID NOW and Sofia assays in the public health response to the coronavirus disease 2019 pandemic and in future public health emergencies.MethodsA combination of utilization and contamination testing in addition to a review of instrument workflows was conducted.ResultsUtilization testing demonstrated that both tests are intuitive, associated with high user test success (85%) in our study, and could be implemented by staff after minimal training. Contamination tests revealed potential biosafety concerns due to the open design of the ID NOW instrument and the transfer mechanisms with the Sofia. When comparing the workflow of the ID NOW and the Sofia, we found that the ID NOW was more user-friendly and that the transfer technology reduces the chance of contamination.ConclusionsThe ID NOW, Sofia, and other emerging point-of-care tests should be used only after careful consideration of testing workflow, biosafety risk mitigations, and appropriate staff training.
| S-EPMC8336596 | biostudies-literature
Project description:Although nasopharyngeal samples have been considered the gold standard for COVID-19 testing, variability in viral load across different anatomical sites could cause nasopharyngeal samples to be less sensitive than saliva or nasal samples in certain cases. Self-collected samples have logistical advantages over nasopharyngeal samples, making them amenable to population-scale screening. To evaluate sampling alternatives for population screening, we collected nasopharyngeal, saliva, and nasal samples from two cohorts with varied levels and types of symptoms. In a mixed cohort of 60 symptomatic and asymptomatic participants, we found that saliva had 88% concordance with nasopharyngeal samples when tested in the same testing lab (n = 41) and 68% concordance when tested in different testing labs (n = 19). In a second cohort of 20 participants hospitalized for COVID-19, saliva had 74% concordance with nasopharyngeal samples tested in the same testing lab but detected virus in two participants that tested negative with nasopharyngeal samples on the same day. Medical record review showed that the saliva-based testing sensitivity was related to the timing of symptom onset and disease stage. We find that no sample site will be perfectly sensitive for COVID-19 testing in all situations, and the significance of negative results will always need to be determined in the context of clinical signs and symptoms. Saliva retained high clinical sensitivity for early-stage and presymptomatic COVID-19 while allowing easier collection, minimizing the exposure of health care workers, and need for personal protective equipment and making it a viable option for population-scale testing. IMPORTANCE Methods for COVID-19 detection are necessary for public health efforts to monitor the spread of disease. Nasopharyngeal samples have been considered the best approach for COVID-19 testing. However, alternative samples like self-collected saliva offer advantages for population-scale screening. Meta-analyses of recent studies suggest that saliva is useful for detecting SARS-CoV-2; however, differences in disease prevalence, sample collection, and analysis methods still confound strong conclusions on the utility of saliva compared to nasopharyngeal samples. Here, we find that the sensitivity of saliva testing is related to both the timing of the sample collection relative to symptom onset and the disease stage. Importantly, several clinical vignettes in our cohorts highlight the challenges of medical decision making with limited knowledge of the associations between laboratory test data and the natural biology of infection.
| S-EPMC8552797 | biostudies-literature
Project description:Point-of-care tests (POCT) for pathogens are considered important for low-resource countries and facilities. Although lateral flow immunoassays (LFIA) have many advantages including speed and ease of use, their sensitivity is limited without specific equipment. Furthermore, their response cannot be enhanced through enzymatic reactions. Owing to these limitations, LFIAs have not yet been generally adopted as the standard protocol for in vitro analysis of infectious pathogens. We aimed to develop a novel pipetting-based immunoassay using a removable magnetic ring-coupled pipette tip. The "magnetic bead-capture antibody-targeted protein complex" was simply purified by pipetting and quantified by enzymatic colour development or using a lateral flow system. This pipetting-based immunoassay was applied to detect the nucleoprotein (NP) of the influenza A virus. Using an HRP-conjugated monoclonal antibody as a probe, the assay allowed for specific and sensitive detection. Furthermore, when this assay was applied exclusively for antigen capture in the lateral flow system, the limit of detection improved 100-fold and displayed greater sensitivity than the lateral flow system alone. Therefore, the pipetting-based immunoassay may be potentially used as a sensitive POCT to clinically detect a target antigen.
| S-EPMC6853919 | biostudies-literature