Ultrasensitive Measurement of Both SARS-CoV-2 RNA and Antibodies from Saliva

Abstract

Tests for COVID-19 generally measure SARS-CoV-2 viral RNA from nasal swabs or antibodies against the virus from blood. It has been shown, however, that both viral particles and antibodies against those particles are present in saliva, which is more accessible than both swabs and blood. We present methods for highly sensitive measurements of both viral RNA and antibodies from the same saliva sample. We developed an efficient saliva RNA extraction method and combined it with an ultrasensitive antibody test based on single molecule array (Simoa) technology. We apply our test to the saliva of patients who presented to the hospital with COVID-19 symptoms, some of whom tested positive with a conventional RT-qPCR nasopharyngeal swab test. We demonstrate that combining viral RNA detection by RT-qPCR with antibody detection by Simoa identifies more patients as infected than either method alone. Our results demonstrate the utility of combining viral RNA and antibody testing from saliva, a single easily accessible biofluid.

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“…The most widely used current diagnostic method, real-time polymerase chain reaction (RT-PCR) testing, is the gold standard and the most accessible diagnostic tool for SARS-CoV-2 identification. 6 , 7 …”

Unified platform for genetic and serological detection of COVID-19 with single-molecule technology

“…Furthermore, additional studies on larger cohorts, as well as systematical comparisons to additional available serological tests are needed. Finally, combined single-molecule based detection of both viral RNA and antibodies was recently demonstrated by Ter-Ovanesyan and colleagues for saliva samples [28]. The use of saliva samples which contain both viral RNA and antibodies against viral particles holds great potential and can be further explored for analysis by our adaptable single-molecule platform.…”

A New Saliva-Based Lateral-Flow SARS-CoV-2 IgG Antibody Test for mRNA Vaccination

“…Saliva represents an appealing biofluid for non-invasive SARS-CoV-2 antibody detection, with the ease of self-collection and is pain-free. Previous work has shown that IgG antibodies in saliva correlated well with those in blood for various infectious diseases including SARS-CoV-2 11,[23][24][25][26][27][28][29][30][31][32] . However, a challenge of saliva sample testing is the much lower concentration of antibodies present than in serum, plasma and blood, demanding high analytical sensitivity of detection methods 33 .…”