Sensitive detection and quantification of SARS-CoV-2 in saliva

Abstract

Saliva has significant advantages as a test medium for detection of SARS-CoV-2 infection in patients, such as ease of collection, minimal requirement of supplies and trained personnel, and safety. Comprehensive validation in a large cohort of prospectively collected specimens with unknown SARS-CoV-2 status should be performed to evaluate the potential and limitations of saliva-based testing. We developed a saliva-based testing pipeline for detection of SARS-CoV-2 nucleic acids using real-time reverse transcription PCR (RT-PCR) and droplet digital PCR (ddPCR) readouts, and measured samples from 137 outpatients tested at a curbside testing facility and 29 inpatients hospitalized for COVID-19. These measurements were compared to the nasal swab results for each patient performed by a certified microbiology laboratory. We found that our saliva testing positively detects 100% (RT-PCR) and 93.75% (ddPCR) of curbside patients that were identified as SARS-CoV-2 positive by the Emergency Use Authorization (EUA) certified nasal swab testing assay. Quantification of viral loads by ddPCR revealed an extremely wide range, with 1 million-fold difference between individual patients. Our results demonstrate for both community screening and hospital settings that saliva testing reliability is on par with that of the nasal swabs in detecting infected cases, and has potential for higher sensitivity when combined with ddPCR in detecting low-abundance viral loads that evade traditional testing methods.

Glycan reactive anti-HIV-1 antibodies bind the SARS-CoV-2 spike protein but do not block viral entry

“…No neutralization capabilities were detected for 2G12, PGT128, and PGT126 over a wide range of concentrations, while V H -FC ab8 demonstrated potent neutralization, in keeping with previous reports 23 . As antibody-dependent enhancement (ADE) of infection has been described for SARS-CoV-2 via engagement of cellular FcγRII receptors 25 , we evaluated the potential for antibody directed enhancement of infection (ADE) by these antibodies, in the FcγRII receptor expressing K562 erythroleukemic cell line 26 (Fig. 2 c).…”

Seroprevalence of anti-SARS-CoV-2 total antibody is higher in younger Austrian blood donors

“…Gallian et al used neutralizing antibody tests. However, there are studies indicating that not all individuals who recovered from a SARS-CoV-2 infection express detectable levels of neutralizing antibodies [ 21 ]. Zietz et al used swab tests, which were recently reported to differ substantially in analytical sensitivity and specificity [ 22 ].…”

Development of multiplex real-time RT-PCR assay for the detection of SARS-CoV-2

“…Additionally, RNA-dependent RNA polymerase (RdRP) gene encodes an enzyme responsible for viral replication. These indispensable genes are the main target for the molecular detection of SARS-CoV-2 [12,[26][27][28][29]. Kakhki et al [30] PLOS ONE reported that ORF8 gene is a possible target for detecting COVID-19 and it is different from reported genes (RdRP, E and N genes), and ORF8 is fully specific to COVID-19 and has no cross-reactivity with other types of coronaviruses.…”