Implementing a rapid and sensitive method to quantify both SARS-CoV-2 viral load and immunity in communities.

Graber, Tyson | $237,970

Ontario Children's Hospital of Eastern Ontario 2021 SSHRC

Our multidisciplinary team was the first in the world to publicly report daily SARS-CoV-2 (CoV-2) RNA in community wastewaters ([]( Used by Ottawa Public Health, this wastewater-based pathogen surveillance system can anticipate changes in community COVID‑19 burden by several days and is thus a valuable adjunct to traditional clinical surveillance methods.

Despite this, day-to-day variability of the fragile viral RNA biomarker has been an issue and the low levels reported often skirt the method’s limits of detection and quantitation. It also does not directly gauge daily levels of “community immunity”, a metric that would be extremely valuable to public health units given the long lead times and logistical complexity of existing serology-based surveys.

To this end, using a highly sensitive, quantitative immuno-linked PCR method called Multiplex Paired-antibody Amplified Detection (MPAD), we have quantified CoV-2 protein in wastewaters at levels in far greater excess of viral RNA. The normalized CoV-2 protein data correlate well with both wastewater-based CoV-2 RNA signal and public health metrics (i.e., PCR testing and hospitalizations). In addition, our preliminary analysis has shown the presence of secretory IgA (SIgA) in wastewater at levels suitable for detection by MPAD.

The objectives of this proposal are to:

1) Validate MPAD assays for quantification of CoV-2 proteins (Spike and Nucleocapsid) and anti-CoV-2 spike protein SIgA in wastewater.

2) Compare sensitivity and reproducibility of protein- vs. RNA-based detection of SARS-CoV-2 in wastewater.

3) Establish a wastewater-derived measure of community immunity and determine any correlation with clinical seroprevalence.

Our established network enables sampling at locations that service indigenous communities and long-term care facilities. These relationships are critical for the successful completion of the objectives. At the same time, deploying these immunoassays in communities will provide actionable information to local public health units.

We believe that quantitative profiling of CoV-2 protein and antibodies from wastewater in rapid time represents a facile and sensitive epidemiological tool to follow community prevalence of fecally-shed pathogens and immunological correlates of protection. As such, the deliverables represent an entirely new epidemiological methodology and tools that can be applied to other infectious diseases, in addition to COVID-19.

With funding from the Government of Canada

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