Stored urine is an established substitute for inorganic fertilizer, and understanding user exposure to pathogens present in urine is critical. Double-stranded DNA (dsDNA) viruses persist in urine; therefore, we set out to characterize the cause of their persistence using bacteriophage T3, a surrogate for human dsDNA viruses, in stored urine at pilot and bench scales. In contrast to the single-stranded RNA bacteriophage MS2, infectious T3 decreased by only 2.5-log10 during the six-month storage period recommended by the World Health Organization. Unexpectedly, T3 persisted longer in urine (kobs = 0.024 d–1) than in synthetic urine (kobs = 0.061 d–1) and phosphate-buffered saline (PBS, kobs = 0.15 d–1). This increased persistence in urine could not be attributed to differences in pH, electrical conductivity, ammonia concentration, and microbial and enzymatic activities; however, the addition of protein to PBS decreased T3 inactivation by 38-fold. Our results imply that protein in urine increases the persistence of T3, and potentially other viruses, which may warrant a reconsideration of urine processing guidelines. This work reinforces the importance of understanding the mechanisms of virus persistence, which can inform suitable storage times or urine processing technologies, and identifying appropriate surrogates to monitor virus persistence in urine.
Li et al. (Fri,) studied this question.