The following is a summary of “Effects of RT-qPCR standards on reproducibility and comparability in monitoring SARS-CoV-2 levels in wastewater,” published in the October 2024 issue of Infectious Disease by Juutinen et al.
Reverse transcription-quantitative PCR (RT-qPCR) has been widely employed to monitor viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in wastewater, utilizing various materials such as plasmid DNA, synthetic nucleic acids, PCR amplicons, genomic DNA, and cDNA to generate standard curves for quantification.
Researchers conducted a study to assess the performance of 3 common standards for quantifying SARS-CoV-2 RNA in wastewater samples from 9 wastewater treatment plants in Finland as part of the national wastewater surveillance program.
They compared RT-qPCR results from 148 wastewater samples using both IDT (#10006625, IDT, USA) and CODEX standards (#SC2-RNAC-1100, CODEX DNA), along with 179 samples using IDT and EURM019 standards (#EURM-019, European Commission, Joint Research Centre).
The results showed that the CODEX standard provided more stable results among the tested standards than the IDT and EURM019 standards, SARS-CoV-2 levels were significantly higher with the IDT standard (4.36 Log10 GC/100 mL) than the CODEX standard (4.05 Log10 GC/100 mL). Additionally, quantification with the IDT standard (5.27 Log10 GC/100 mL) exceeded values obtained with the EURM019 standard (4.81 Log10 GC/100 mL), the SARS-CoV-2 RNA quantified using IDT and CODEX standards showed stronger concordance (Spearman’s correlation rho median of 0.79) than those quantified with IDT and EURM019 standards (rho median of 0.59).
They concluded the choice of standard material affected SARS-CoV-2 RNA quantification in wastewater, emphasizing the need of harmonizing standard materials.