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The Assessment of Two Volumetrically Different Concentration Approaches to Improve Sensitivities for SARS-CoV-2 Detection During Wastewater Surveillance
Citation:
McMinn, B., A. Korajkic, A. Pemberton, J. Kelleher, AND W. Ahmed. The Assessment of Two Volumetrically Different Concentration Approaches to Improve Sensitivities for SARS-CoV-2 Detection During Wastewater Surveillance. 2022 American Society for Microbiology Microbe Meeting, Washington, DC, June 09 - 13, 2022.
Impact/Purpose:
This research project investigated losses of SARS-CoV-2 infectious and molecular signal during two different wastewater concentration methods.
Description:
Wastewater monitoring for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), responsible for the global pandemic of coronavirus disease 2019 (COVID-19) has highlighted the need for improved methodologies capable of better forecasting viral spread, monitoring emergence of viral variants, and generating data relevant to clinical surveillance efforts. Two volumetrically different, methodologically similar concentration approaches were compared for their ability to recover both infectious and gene fragments of SARS-CoV-2 from primary influent samples. For Method 1; we evaluated a dead-end hollow fiber ultrafilter (D-HFUF) for primary concentration, followed by a Concentrator Pipette Select™ (CP Select™) secondary concentration step for 2L volumes of SARS-CoV-2 seeded wastewater. For Method 2; we evaluated the CP Select™ as a small-scale solution (100mL SARS-CoV-2 seeded wastewater). Subsampling was conducted to characterize losses of SARS-CoV-2 (culturable and molecular signal) during each method procedural step. Assessments of SARS-CoV-2 seeding stocks revealed a nearly 4-fold difference between SARS-CoV-2 qPCR N1 and N2 RT-qPCR signal compared to that of SARS-CoV-2 infectious signal measured by cell culture assay. Following D-HFUF concentration (Method 1), significantly higher levels of infectious SARS-CoV-2 were lost (P value range: 0.0398 to 0.0027) compared to levels of the viral qPCR molecular signal. During centrifugation (prior to CP Select™ concentration) significantly greater losses (P value range: 0.0003 to <0.0001) occurred for SARS-CoV-2 molecular signal compared to infectious for Method 1. Infectious virus signal losses for Method 2 were greater than Method 1 (P = 0.0002). Application of Method 1 for endogenous SARS-CoV-2 improved detection assay sensitivities (P= <0.0001) over Method 2, concentrations detected concurring with active COVID-19 case rates in the sewer shed. Findings suggest that large volume concentration methodologies will be critical for forecasting spread of SARS-CoV-2 during wastewater surveillance efforts to gain better estimates of viral spread in communities.