On the detection of foodborne viral contamination in edible seaweeds

The consumption of edible seaweed as a sustainable food source is increasing; however, their complex composition and diverse commercial formats pose significant challenges for the detection of pathogens, specifically human enteric viruses. Standardized methods, such as ISO 15216-1:2017 and FDA/BAM, are available for detecting and quantifying viral contamination in a diversity of food matrices, which is crucial to guarantee food safety and implement routine monitoring efforts. However, these methodologies demonstrated limited efficiency when applied to complex food samples, and information on their analytical performance is not available for edible seaweed, yet. In this study, three viral concentration protocols based on ISO or FDA/BAM procedures were comparatively assessed for their analytical performance in detecting human norovirus genogroups I and II (HuNoV GI and GII), hepatitis A virus (HAV), and human astrovirus (HAstV) in three edible seaweed species (Codium spp., Ulva lactuca, and Himanthalia elongata). Among assessed protocols, FDA/BAM method exhibited the highest sensitivity (LoD_50% = 5.0 ± 0.8 log GC/25 g) and recovery efficiency (2.2-10.9%), significantly outperforming the alternatively tested ISO-based methods. In addition, the best-performing method was employed to conduct a pilot assessment of viral contamination in commercial seaweeds sold in different formats (fresh, dried, and powdered). The sampling campaign resulted in Ulva lactuca (3/15; 20.0%) and Sargassum muticum (1/15; 6.7%) contaminated with HuNoV GII RNA. Overall, these findings emphasise the need for sensitive and standardized detection methods for enteric viruses in complex food matrices, such as seaweeds.