Study on the Effect of Relaying on Norovirus Reduction from Crassostrea gigas Oysters

• Published in: Microorganisms
• Main Authors: Roberta Battistini, Chiara Masotti, Cristiana Maurella, Erica Costa, Mino Orlandi, Mirvana Feletti, Carlo Ercolini, Laura Serracca
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2022
• Subjects: Crassostrea gigas; relay; norovirus; food safety; real-time qPCR; Biology (General); QH301-705.5
• Online Access: https://doi.org/10.3390/microorganisms10122389; https://doaj.org/article/583cace996924006b2829ec3625c1161

Norovirus (NoV) is the most important cause of seafood-borne gastroenteritis worldwide, mainly associated with the consumption of raw oysters. NoV is often present in oysters that comply with existing control standards for shellfish. Therefore, the improvement of post-harvest treatments and practices can represent one of the main strategies to reduce the incidence of viral diseases related to shellfish. This study aimed to investigate long-term relays for the reduction of NoV levels in live oysters, during the high-risk cold months, by transferring the oysters from a more contaminated site to two sites with lower NoV levels. The efficacy of relaying was evaluated by analyzing oyster samples collected at days 0 (T0) and 30 (T30) for NoV levels using a real-time quantitative PCR (RT-qPCR). The NoV level at the relay sites was consistently lower than at the harvest site. The relay process for 30 days in seawater with a lower NoV level resulted in a decrease in the NoV load compared to day 0 with significant reductions depending on the site and genogroup of NoV considered. These results suggest that long-term relaying of oysters to reduce NoV levels is promising and could help growers to improve oyster safety; however, further investigations are needed.