Developing Cross-Assembly Phage as a Viral Indicator for Irrigation Waters

Ensuring high-quality irrigation water is necessary to protect the public when consuming minimally processed produce. The highest risk from exposure to contaminated water is due to viruses; however, water quality is currently monitored using bacteria that are poor representatives of viruses. All previous viral indicators are limited by a low abundance (i.e. difficult to detect) in the environment. Recently, a bacteriophage (virus that infects bacteria) named ‘cross-assembly phage’ (crAssphage) was discovered that is more abundant than all other bacteriophages in the human gut combined. Investigations in the PI’s research group have shown crAssphage to be highly abundant in sewage. As crAssphage is a virus, it will be a better representative of viral contamination in the environment. In this investigation, I propose to sample irrigation water samples and measure crAssphage, viruses, and indicators in these samples to demonstrate the correlation of crAssphage and pathogens. I also proposed to determine how much sample volume is necessary to accurately measure crAssphage. The development of this viral monitoring tool, catalyzed by funding this project, will enable risk-managers to have an accurate and abundant indicator of viral contamination. This will ultimately provide greater protection of public health and improve consumer confidence in produce consumption.