- Award ID(s):
- 2035114
- Publication Date:
- NSF-PAR ID:
- 10330112
- Journal Name:
- Scientific Reports
- Volume:
- 11
- Issue:
- 1
- ISSN:
- 2045-2322
- Sponsoring Org:
- National Science Foundation
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Highly sensitive, specific, and point-of-care (POC) serological assays are an essential tool to manage coronavirus disease 2019 (COVID-19). Here, we report on a microfluidic POC test that can profile the antibody response against multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens—spike S1 (S1), nucleocapsid (N), and the receptor binding domain (RBD)—simultaneously from 60 μl of blood, plasma, or serum. We assessed the levels of antibodies in plasma samples from 31 individuals (with longitudinal sampling) with severe COVID-19, 41 healthy individuals, and 18 individuals with seasonal coronavirus infections. This POC assay achieved high sensitivity and specificity, tracked seroconversion, and showed good concordance with a live virus microneutralization assay. We can also detect a prognostic biomarker of severity, IP-10 (interferon-γ–induced protein 10), on the same chip. Because our test requires minimal user intervention and is read by a handheld detector, it can be globally deployed to combat COVID-19.
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Abstract Background: Retinol-binding protein (RBP) is accepted as a surrogate biochemical marker for retinol to determine vitamin A (VA) status. A recently developed enzyme immunoassay for RBP uses serum or whole blood stored as dried blood spots (DBS). However, the stability of RBP in DBS has not been examined.
Methods: RBP stability was studied in a laboratory and in field conditions in northern Kenya. For the laboratory study, 63 DBS collected by finger prick and stored sealed in a plastic bag with desiccant were exposed to 1 of 5 time/storage-temperature treatments: (a) baseline, (b) 30 °C/7 days, (c) 30 °C/14 days, (d) 30 °C/28 days, and (e) 4 °C/38 days. Baseline RBP concentrations were compared to those obtained after the storage treatments. For the field study, 50 paired DBS and serum specimens were prepared from venous blood obtained in northern Kenya. DBS were stored in a sealed plastic bag with desiccant at ambient temperature (12 °C–28 °C) for 13–42 days, and sera were stored at −20 °C to −70 °C. Recovered RBP concentrations were compared with serum retinol for stability, correlation, sensitivity, and specificity.
Results: RBP in DBS stored in the laboratory at 30 °C remained stable for 2–4 weeks,more »
Conclusion: RBP in DBS can withstand storage at a relatively high ambient temperature and thus facilitate accurate VA assessments in populations in locations where serum collection and storage are unfeasible.
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