Search for: All records

Human exposure to pathogenic viruses in environmental waters results in a significant global disease burden. Current microbial water quality monitoring approaches, mainly based on fecal indicator bacteria, insufficiently capture human health impacts posed by pathogenic viruses in water. The emergence of the ‘microbiome era’ and high-throughput metagenome sequencing has led to the discovery of novel human-associated viruses, including both pathogenic and commensal viruses in the human microbiome. The discovery of novel human-associated viruses is often followed by their detection in wastewater, highlighting the great diversity of human-associated viruses potentially present in the water environment. Novel human-associated viruses provide a rich reservoir to develop viral water quality management tools with diverse applications, such as regulating wastewater reuse and monitoring agricultural and recreational waters. Here, we review the pathway from viral discovery to water quality monitoring tool, and highlight select human-associated viruses identified by metagenomics and subsequently detected in the water environment (namely Bocavirus, Cosavirus, CrAssphage, Klassevirus, and Pepper Mild Mottle Virus). We also discuss research needs to enable the application of recently discovered human-associated viruses in water quality monitoring, including investigating the geographic distribution, environmental fate, and viability of potential indicator viruses. Examples suggest that recently discovered human pathogens are likely to be less abundant in sewage, while other human-associated viruses (e.g., bacteriophages or viruses from food) are more abundant but less human-specific. The improved resolution of human-associated viral diversity enabled by metagenomic tools provides a significant opportunity for improved viral water quality management tools.

 

Fecal indicator bacteria currently used for water quality monitoring inadequately represent viral fate in water systems, motivating the development of viral fecal pollution indicators. Molecular viral fecal pollution indicators such as crAssphage and pepper mild mottle virus (PMMoV) have emerged as leading viral fecal pollution indicator candidates due to ease and speed of measurement and target specificity. Elucidating the fate of molecular viral fecal indicators in water systems is necessary to facilitate their development, broader adoption, and ultimately their association with infectious risk. A significant mechanism controlling the behavior of viral indicators in environmental waters is association with particles, as this would dictate removal via settling and transport characteristics. In this study, we investigated the particle associations of six molecular fecal pollution targets (crAssphage, PMMoV, adenovirus, human polyomavirus, norovirus, HF183/BacR287) in wastewater using a cascade filtration approach. Four different filters were employed representing large settleable particles (180 μm), larger (20 μm) and smaller suspended particles (0.45 μm), and non-settleable particles (0.03 μm). All molecular targets were detected on all particle size fractions; however, all targets had their highest concentrations on the 0.45 μm (percent contribution ranging from 40% to 80.5%) and 20 μm (percent contribution ranging from 3.9% to 39.4%) filters. The association of viral fecal pollution targets with suspended particles suggests that particle association will dictate transport in environmental waters and that sample concentration approaches based upon particle collection will be effective for these targets.