In silico analysis reveals differential targeting of enterovirus species by commonly used PCR assays

Quantitative polymerase chain reaction (qPCR) assays are sensitive molecular tools commonly used to quantify pathogens in environmental samples. These assays have become a staple of wastewater-based surveillance and often form the basis of quantitative microbial risk assessments. However, PCR assays may fail to capture all of their intended targets due to signature erosion over time. Here, we performed an in silico analysis of four human enterovirus PCR assays to assess signature erosion against the NCBI virus database. The predicted number of genomes hit by each assay rose alongside total genomes in the database through 2010 but the proportion of predicted hits began to level off with the emergence of the clinically important enterovirus D-68. We found that although all assays captured a majority of enterovirus species, only one recently developed assay adequately captured enterovirus D species. Some assays also appeared more likely to capture non-human enteroviruses than others, an important consideration for data interpretation. We conclude that broad-spectrum virus assays applied to environmental samples should be regularly checked against expanding sequence databases and provide methods to do so.