The role of pipe biofilms on dissemination of viral pathogens and virulence factor genes in a full-scale drinking water supply system

Water is an important medium for virus transmission and viral pathogens are increasingly appreciated as a significant water safety issue. However, the effect of pipe biofilms on viral pathogens remains unclear. This research aimed to investigate the dissemination of viruses in a full-scale drinking water supply system (DWSS) and the effect of pipe biofilms on viral pathogens in bulking water. Viral pathogens, pathogenic viral hosts, and viral virulence factors (VFs) were found to disseminate from source water to tap water. The proportion of virus and viral VFs in the biofilm was far less than that in water. The contribution of biofilms in pipe wall to viruses and viral VFs in bulking water was less than 4%, and viruses in the biofilm had no obvious effect on pathogenic viruses in water. Dominant viruses carrying VFs changed from Cyanobacteria virus to Mycobacterium virus after advanced water treatment. Mycobacterium and organics were identified as the key factors influencing compo-sition and abundance of viral VFs, which could explain 41.1% of the variation in viral virulence in the water supply system. Host bacteria and organics may be used as the key targets to control the risk of viruses in DWSSs.

Automated summary

Water is an important medium for virus transmission and the role of pipe biofilms on viral pathogens is limited. This study found that viruses and viral virulence factors can disseminate from source water to tap water, but the proportion in biofilms is low. The contribution of biofilms to viral pathogens in bulk water is minimal and viruses in biofilms have minimal impact on pathogenic viruses in water.