Evaluation of Human- and Animal-Specific Viral Markers and Application of CrAssphage, Pepper Mild Mottle Virus, and Tobacco Mosaic Virus as Potential Fecal Pollution Markers to River Water in Japan.

Five human-specific markers were detected in 59-74% of 27 human fecal-source samples collected in Yamanashi Prefecture, Japan. Similarly, potential human-specific markers, crAssphage, pepper mild mottle virus (PMMoV), and tobacco mosaic virus were detected in 96-100% of samples, with crAssphage showing the maximum concentration of 12.03 log copies/L. However, these markers were detected in 100% (3/3) of pig fecal-source samples, suggesting their applicability as general fecal pollution markers. Microbial source tracking analysis demonstrated that the rivers are contaminated by human and pig fecal sources. CrAssphage showed higher marker concentrations in river water samples than PMMoV, suggesting the preference of crAssphage to PMMoV as a marker of fecal pollution.