posted on 2021-03-24, 15:20authored byOscar
N. Whitney, Lauren C. Kennedy, Vinson B. Fan, Adrian Hinkle, Rose Kantor, Hannah Greenwald, Alexander Crits-Christoph, Basem Al-Shayeb, Mira Chaplin, Anna C. Maurer, Robert Tjian, Kara L. Nelson
Wastewater-based
epidemiology is an emerging tool to monitor COVID-19
infection levels by measuring the concentration of severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater. There remains
a need to improve wastewater RNA extraction methods’ sensitivity,
speed, and reduce reliance on often expensive commercial reagents
to make wastewater-based epidemiology more accessible. We present
a kit-free wastewater RNA extraction method, titled “Sewage,
Salt, Silica and SARS-CoV-2” (4S), that employs the abundant
and affordable reagents sodium chloride (NaCl), ethanol, and silica
RNA capture matrices to recover sixfold more SARS-CoV-2 RNA from wastewater
than an existing ultrafiltration-based method. The 4S method concurrently
recovered pepper mild mottle virus (PMMoV) and human 18S ribosomal
subunit rRNA, which have been proposed as fecal concentration controls.
The SARS-CoV-2 RNA concentrations measured in three sewersheds corresponded
to the relative prevalence of COVID-19 infection determined via clinical
testing. Lastly, controlled experiments indicate that the 4S method
prevented RNA degradation during storage of wastewater samples, was
compatible with heat pasteurization, and in our experience, 20 samples
can be processed by one lab technician in approximately 2 h. Overall,
the 4S method is promising for effective, economical, and accessible
wastewater-based epidemiology for SARS-CoV-2, providing another tool
to fight the global pandemic.