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Low saliva pH can yield false positives results in simple RT-LAMP-based SARS-CoV-2 diagnostic tests
PLoS One. 2021 ;16(5) :e0250202
PMID: 33951060    PMCID: PMC8099103   
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Diagnosis of any infectious disease is vital for opportune treatment and to prevent dissemination. RT-qPCR tests for detection of SARS-CoV-2, the causative agent for COVID-19, are ideal in a hospital environment. However, mass testing requires cheaper and simpler tests, especially in settings that lack sophisticated machinery. The most common current diagnostic method is based on nasopharyngeal sample collection, RNA extraction, and RT-qPCR for amplification and detection of viral nucleic acids. Here, we show that samples obtained from nasopharyngeal swabs in VTM and in saliva can be used with or without RNA purification in an isothermal loop-mediated amplification (LAMP)-based assay, with 60-93% sensitivity for SARS-CoV-2 detection as compared to standard RT-qPCR tests. A series of simple modifications to standard RT-LAMP published methods to stabilize pH fluctuations due to salivary acidity resulted in a significant improvement in reliability, opening new avenues for efficient, low-cost testing of COVID-19 infection.
1932-6203 Uribe-Alvarez, Cristina Orcid: 0000-0001-8328-5950 Lam, Quynh Baldwin, Don A Orcid: 0000-0002-1853-9253 Chernoff, Jonathan P30 CA006927/CA/NCI NIH HHS/United States Journal Article Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't PLoS One. 2021 May 5;16(5):e0250202. doi: 10.1371/journal.pone.0250202. eCollection 2021.