Internalization and Localization of Murine Norovirus in Hydroponically Grown Green Onion (Allium Fistulosum L.)

Norovirus is a leading etiological agent of foodborne illnesses globally, with fresh produce serving as a significant vector for its transmission to humans. This study investigated the internalization potential of norovirus from contaminated irrigation water, focusing on the temporal distribution, persistence, and removability of murine norovirus (MNV) in hydroponically grown green onions. Our results demonstrated that MNV rapidly internalized into the root tissues of green onions within 1 h of exposure, subsequently translocating through the vascular system to the stems and leaves. Viral loads consistently peaked in the roots and persisted for at least 21 days post-inoculation. A single water exchange procedure resulted in a gradual decrease in viral load within plant tissues, although viral genomes remained detectable for up to 21 days. Repeated water exchanges effectively cleared the virus from leaves and stems but failed to eradicate it entirely from the roots. Immunofluorescence analysis localized the virus predominantly within the vascular tissues, specifically the xylem and phloem vessels, and most notably on the rough, porous surfaces of root hairs, where viral particles persisted despite rigorous washing protocols. Collectively, these findings unequivocally demonstrate that MNV can rapidly internalize and establish a sustained, long-term presence within green onion plants, particularly concentrated in the root tissues. This underscores the imperativeness of stringent pre-harvest preventive strategies to mitigate the risk of viral contamination in hydroponic cultivation systems.